Method and apparatus for performing backoff in a two-step random access procedure in a wireless communication system

Abstract

The present disclosure relates to a communication method and system for integrating a fifth generation (5G) communication system supporting a higher data rate than a fourth generation (4G) system with Internet of Things (IoT) technology. The present disclosure can be applied to smart services based on 5G communication technology and IoT-related technologies, such as smart homes, smart buildings, smart cities, smart cars, Internet of Vehicles, healthcare, digital education, smart retail, security and safety services, etc. The present invention discloses a method for applying backoff when using two-step random access.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for applying backoff when a two-step random access procedure is used in a wireless communication system. Background Art

[0002] In order to meet the increased demand for wireless data traffic since the deployment of 4G communication systems, efforts have been made to develop improved 5G or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also called "beyond 4G networks" or "post-LTE systems". 5G communication systems are considered to be implemented in higher (mmWave) frequency bands, such as the 60GHz band, to achieve higher data rates. In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple input multiple output (MIMO), full-size MIMO (FD-MIMO), array antennas, analog beamforming and massive antenna technology are discussed relative to 5G communication systems. In addition, in 5G communication systems, improvements and developments are being made based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, system networks, collaborative communications, collaborative multi-point (CoMP), receiving-end interference elimination, etc. In 5G systems, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) have been developed as advanced coded modulation (ACM), and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access techniques.

[0003] The Internet is a human-centric connected network where people generate and consume information. Today, the Internet is developing into the Internet of Things (IoT), where information can be exchanged and processed by distributed entities such as objects without human intervention. The Internet of Everything (IoE) has emerged, which is a combination of IoT technology and big data processing technology achieved by connecting to cloud servers. Since the implementation of the IoT requires corresponding technical elements such as "sensing technology", "wired / wireless communication and network infrastructure", "service interface technology" and "security technology", there are recent studies on sensor networks, machine-to-machine (M2M) communication, machine-type communication (MTC), etc. Such IoT environments can provide smart Internet technology services that create new value for human life by collecting and analyzing data generated between connected objects. Through the integration and combination between existing information technology (IT) and various industrial technologies, the IoT can be applied to various fields, including smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart appliances, and advanced medical services.

[0004] Accordingly, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine type communications (MTC), and machine-to-machine (M2M) communications can be implemented through beamforming, MIMO, and array antennas. Cloud radio access networks (RANs) as an application of the above-mentioned big data processing technologies can also be seen as an example of the integration of 5G technology and IoT technology. Summary of the invention

[0005]

Technical issues

[0006] An aspect of the present disclosure provides a method for indicating a backoff when a base station has received an entire MsgA related to a two-step random access and when a part of the MsgA (Msg1) has been received.

[0007]

Problem Solution

[0008] To solve the above problems, the present invention provides a method for performing random access by a terminal in a wireless communication system, the method comprising: receiving a preconfigured threshold and random access related information from a base station; determining the random access type to be one of a two-step random access type and a four-step random access type based on the preconfigured threshold and received signal strength received from the base station; sending a signal related to a first preamble code of the random access to the base station; based on the determined random access type and the random access related information, if the determined random access type is a two-step random access type, in Msg B according to the two-step random access type and Msg 2 according to the four-step random access type, identifying a backoff indicator included in Msg B; if the determined random access type is a four-step random access type, in Msg B according to the two-step random access type and Msg 2 according to the four-step random access type, identifying a backoff indicator included in Msg 2; and sending a signal related to a second preamble code to the base station based on the identified backoff indicator.

[0009] Alternatively, the present disclosure provides a method for performing random access through a base station in a wireless communication system, the method comprising: sending a preconfigured threshold and random access-related information to a terminal; receiving a signal related to a first preamble code determined based on a random access type and random access-related information from the terminal; sending Msg B and Msg 2 including a backoff indicator to the terminal in response to the signal related to the first preamble code; and receiving a signal related to a second preamble code from the terminal based on the backoff indicator identified by the terminal, wherein the backoff indicator identified by the terminal is an indicator of a backoff indicator in Msg B included in Msg 2 and Msg B when the random access type determined by the terminal is a two-step random access type, and the backoff indicator identified by the terminal is an indicator of a backoff indicator in Msg 2 included in Msg 2 and Msg B when the random access type determined by the terminal is a four-step random access type.

[0010] Alternatively, the present disclosure provides a terminal in a wireless communication system, the terminal comprising: a transceiver, the transceiver being configured to send a signal to a base station or receive a signal from the base station; and a controller, the controller being configured to receive a preconfigured threshold and random access related information from the base station; based on the preconfigured threshold and received signal strength received from the base station; determining that the random access type is one of a two-step random access type and a four-step random access type; based on the determined random access type and the random access related information, sending a signal related to a first preamble code of random access to the base station; in a case where the determined random access type is the two-step random access type, in Msg B according to the two-step random access type and Msg 2 according to the four-step random access type, identifying a backoff indicator included in Msg B, and in a case where the determined random access type is the four-step random access type, in Msg B according to the two-step random access type and Msg2 according to the four-step random access type, identifying a backoff indicator included in Msg 2; and based on the identified backoff indicator, sending a signal related to a second preamble code to the base station.

[0011] Alternatively, the present disclosure provides a base station in a wireless communication system, the base station comprising: a transceiver, the transceiver being configured to send a signal to a terminal or receive a signal from the terminal; and a controller, the controller being configured to send a preconfigured threshold and random access related information to the terminal; receive a signal related to a first preamble code determined based on a random access type and random access related information from the terminal; send Msg B and Msg 2 including a backoff indicator to the terminal in response to the signal related to the first preamble code; and receive a signal related to a second preamble code from the terminal based on the backoff indicator identified by the terminal, wherein the backoff indicator identified by the terminal is an indicator of a backoff indicator in Msg B included in Msg 2 and Msg B when the random access type determined by the terminal is a two-step random access type, and the backoff indicator identified by the terminal is an indicator of a backoff indicator in Msg 2 included in Msg 2 and Msg B when the random access type determined by the terminal is a four-step random access type.

[0012] [Advantageous effects of the present disclosure]

[0013] According to an embodiment of the present invention, when performing two-step random access, the base station may indicate backoff differently depending on which MsgA channel has conflicted, thereby effectively controlling the conflict. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1A The structure of an LTE system according to an embodiment of the present disclosure is shown;

[0015] Figure 1BThe radio protocol architecture in LTE and NR systems according to an embodiment of the present disclosure is shown;

[0016] Figure 1C An example of a downlink and uplink channel frame structure in beam-based communication of an NR system according to an embodiment of the present disclosure is shown;

[0017] Figure 1D A process in which a UE performs a contention-based four-step random access to a base station according to an embodiment of the present disclosure is shown.

[0018] Figure 1E A process in which a UE performs a two-step random access process on a base station according to an embodiment of the present disclosure is shown;

[0019] Figure 1F Embodiment 1 is shown, which is related to a method for determining whether to use BI information included in a message (Msg2 or MsgB) when a UE performs a two-step random access according to an embodiment of the present disclosure;

[0020] Figure 1G Embodiment 2 is shown, which is related to a method for determining whether to use BI information included in a message (Msg2 or MsgB) when a UE performs a two-step random access according to an embodiment of the present disclosure;

[0021] Figure 1H Embodiment 3 is shown, which is related to a method for determining whether to use BI information included in a message (Msg2 or MsgB) when a UE performs a two-step random access according to an embodiment of the present disclosure;

[0022] Fig. 1I A block diagram of a UE in a wireless communication system according to an embodiment of the present disclosure is shown;

[0023] Figure 2 The structure of a UE according to an embodiment of the present disclosure is shown; and

[0024] Figure 3 The structure of a base station according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0025] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the following description of the present disclosure, a detailed description of known functions or configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure unnecessarily unclear. The terms to be described below are terms defined in consideration of the functions in the present disclosure and may vary depending on the user, user intent or custom. Therefore, the definition of the terms should be based on the content of the entire specification.

[0026] The advantages and features of the present invention and its implementation will become apparent by reference to the embodiments described in detail below in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided only to fully disclose the present disclosure and inform those skilled in the art of the scope of the present disclosure, and the present disclosure is limited only by the scope of the attached claims. Throughout the specification, the same or similar reference numerals represent the same or similar elements.

[0027] In the following description, for convenience, terms used to identify access nodes, terms related to network entities, terms related to messages, terms related to interfaces between network entities, terms related to various identification information, etc. are exemplarily used. Therefore, the present disclosure is not limited to the terms used below, and other terms referring to subjects with equivalent technical meanings may be used.

[0028] In the following description, for convenience of description, the present disclosure will be described using terms and names defined in the LTE and NR standards, which are the latest standards specified by the 3rd Generation Partnership Project (3GPP) group in existing communication standards. However, the present disclosure is not limited by these terms and names, and can be applied to systems conforming to other standards in the same manner. Specifically, the present disclosure can be applied to 3GPP NR (fifth generation mobile communication standard).

[0029] Figure 1A The structure of an LTE system according to an embodiment of the present disclosure is shown. The NR system also has a similar structure.

[0030] Reference Figure 1A , the wireless communication system includes multiple eNBs 1a-05, 1a-10, 1a-15 and 1a-20, a mobility management entity (MME) 1a-25 and a serving gateway (S-GW) 1a-30. User equipment (hereinafter referred to as UE or terminal) 1a-35 accesses the external network through the eNBs 1a-05, 1a-10, 1a-15 and 1a-20 and the S-GW 1a-30.

[0031] eNBs 1a-05, 1a-10, 1a-15, and 1a-20 are access nodes of a cellular network and provide wireless connections to UEs accessing the network. That is, eNBs 1a-05, 1a-10, 1a-15, and 1a-20 perform scheduling by collecting status information such as the buffer status, available transmission power status, and channel status of the UE in order to provide service traffic for the user, and support the connection between the UE and the core network (CN). MME1a-25 corresponds to a device that is responsible for various control functions including a mobility management function of the UE and is connected to a plurality of eNBs, and S-GW 1a-30 corresponds to a device that provides data bearers. In addition, MME 1a-25 and S-GW 1a-30 can also perform authentication, bearer management, etc. for UE accessing the network, and process packets arriving from eNBs 1a-05, 1a-10, 1a-10, 1a-15 and 1a-20 or packets to be transmitted to eNBs 1a-05, 1a-10, 1a-15 and 1a-20.

[0032] Figure 1B The wireless protocol architecture in the LTE and NR systems according to an embodiment of the present disclosure is shown.

[0033] Reference Figure 1B, for the wireless protocol structure of the LTE system, each of the UE and the eNB includes a packet data convergence protocol (PDCP) layer 1b-05 or 1b-40, a radio link control (RLC) layer 1b-10 or 1b-35, and a medium access control (MAC) layer 1b-15 or 1b-30. The packet data convergence protocol (PDCP) layer 1b-05 or 1b-40 is responsible for IP header compression / decompression, and the radio link control (hereinafter referred to as RLC) 1b-10 or 1b-35 reconfigures the PDCP packet data unit (PDCP PDU) to an appropriate size. The MAC layer 1b-15 or 1b-30 is connected to a plurality of RLC layer devices configured in one UE, and performs operations of multiplexing RLC PDUs to MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. Physical layers 1b-20 and 1b-25 channel encode high-layer data and modulate the high-layer data into OFDM symbols and transmit the OFDM symbols through a wireless channel, or demodulate and channel decode the OFDM symbols received through the wireless channel to transmit the OFDM symbols to a higher layer. In addition, for additional error correction, hybrid ARQ (HARQ) is used in the physical layer, and the receiver side sends 1-bit information indicating whether the packet sent by the transmitter side is received. This information is called HARQ ACK / NACK information. In the case of an LTE system, downlink HARQ ACK / NACK information for uplink data transmission can be transmitted through a physical hybrid ARQ indicator channel (PHICH). In the case of an NR system, whether retransmission is required or whether retransmission is sufficient can be determined by the scheduling information of the corresponding UE in the physical downlink control channel (PDCCH), where the physical downlink control channel is a channel through which downlink / uplink resource allocation is sent. This is because asynchronous HARQ is applied in the NR system. Uplink HARQ ACK / NACK information for downlink data transmission can be transmitted through the physical uplink control channel (PUCCH) or the physical uplink shared channel (PUSCH) physical channel. PUCCH is usually sent through the uplink of the primary cell (PCell) described below. However, if there is support from the UE, the eNB can additionally send PUCCH to the corresponding UE through the secondary cell (SCell) described below. This SCell is called a PUCCH SCell.

[0034] Although not shown, a radio resource control (RRC) layer exists above the PDCP layer of each of the UE and the eNB, and the RRC layer may transmit or receive a configuration control message related to access and measurement to control radio resources.

[0035] At the same time, the PHY layer may include one or more frequencies / carriers, and the technology of configuring and using multiple frequencies at the same time is called carrier aggregation technology (hereinafter referred to as CA). In the past, the communication between the terminal (or user equipment (UE)) and the base station (E-UTRAN nodeB (eNB)) only used one carrier, but the CA technology can significantly increase the transmission volume and the number of subcarriers by additionally using a main carrier and one or more subcarriers. At the same time, in the LTE system, the cell in the eNB using the main carrier is called the primary cell or primary cell (PCell), and the cell in the eNB using the subcarrier is called the subcell or secondary cell (SCell).

[0036] Figure 1C An example of downlink and uplink channel frame structures in beam-based communication of an NR system according to an embodiment of the present disclosure is shown.

[0037] exist Figure 1C In the exemplary diagram, eNB 1c-01 transmits signals in the form of beams 1c-11, 1c-13, 1c-15, and 1c-17 in order to transmit wider coverage or stronger signals. Accordingly, UE 1c-03 in the cell needs to transmit or receive data by using a specific beam (beam #1 1c-13 in this exemplary diagram) transmitted by the eNB.

[0038] Meanwhile, the state of the UE is divided into an idle mode (RRC_IDLE) and a connected mode (RRC_CONNECTED) according to whether the UE is connected to the eNB. Accordingly, the eNB does not recognize the location of the UE in the idle mode.

[0039] If the UE in idle mode is to be transferred to connected mode, the UE can receive synchronization signal blocks (SSBs) 1c-21, 1c-23, 1c-25, and 1c-27 transmitted by the eNB. The SSBs are periodically transmitted according to the period configured by the eNB, and each of the SSBs may include a primary synchronization signal (PSS) 1c-41, a secondary synchronization signal (SSS) 1c-43, and a physical broadcast channel (PBCH).

[0040] In this exemplary diagram, a scenario in which an SSB is transmitted for each beam is assumed. For example, it is assumed that SSB#0 1c-21 is transmitted using beam#0 1c-11, SSB#1 1c-23 is transmitted using beam#1 1c-13, SSB#2 1c-25 is transmitted using beam#2 1c-15, and SSB#3 1c-27 is transmitted using beam#3 1c-17. In this figure, it is assumed that a UE in idle mode is located in beam#1. However, if a UE in connected mode performs random access, the UE selects an SSB received when performing random access.

[0041] Accordingly, in Figure 1C In the example, the UE receives SSB#1 transmitted using beam#1. If SSB#1 is received, the UE acquires the physical cell identifier (PCI) of the eNB through the PSS and the SSS and receives the PBCH so that the UE can identify the identifier of the currently received SSB (i.e., #1), the position of the currently received SSB within the 10ms frame, and the system frame number (SFN) with a 10.24 second period where the SSB is located. In addition, the PBCH may include a master information block (MIB), and the MIB may include information indicating the position of a system information block type 1 (SIB1) for receiving more detailed configuration information of the broadcast cell. If SIB1 is received, the UE can identify the total number of SSBs transmitted by the eNB and can identify the position of a physical random access channel (PRACH) opportunity (assuming a scenario in which a PRACH opportunity is allocated every 1ms in this example figure: represented by reference marks 1c-30 to 1c-39), where the UE can perform random access to transition to a connected mode (more precisely, capable of transmitting a preamble that is a physical signal designed for uplink synchronization). In addition, the UE can identify that the PRACH opportunity in the PRACH opportunity is mapped to the SSB index based on this information. For example, in this exemplary figure, a scenario in which a PRACH opportunity is allocated every 1ms and a scenario in which half of the SSBs are allocated for each PRACH opportunity (i.e., two PRACH opportunities per SSB) is assumed. Therefore, a scenario in which two PRACH opportunities are allocated to each SSB starting from the PRACH opportunity according to the SFN value is shown. That is, according to the scenario, 1c-30 and 1c-31 are allocated to SSB#0, and 1c-32 and 1c-33 are allocated to SSB#1. After all SSBs are configured, the PRACH opportunity is allocated again for the first SSB (indicated by reference marks 1c-38 and 1c-39).

[0042] Accordingly, the UE identifies the positions of PRACH opportunities 1c-32 and 1c-33 of SSB#1, and transmits a random access preamble at the current earliest PRACH opportunity (e.g., 1c-32) among PRACH opportunities 1c-32 and 1c-33 corresponding to SSB#1. Since the eNB receives the preamble at PRACH opportunity 1c-32, it can be seen that the corresponding UE has transmitted the preamble by selecting SSB#1. Therefore, when performing subsequent random access, data can be transmitted or received through the corresponding beam.

[0043] Meanwhile, when a UE in connected mode moves from a current (source) eNB to a target eNB due to handover or the like, the UE performs random access at the target eNB and selects an SSB as described above to perform the operation of sending a random access preamble. In addition, during the handover process, a handover command is sent to the UE to allow the UE to move from the source eNB to the target eNB. Here, the message may include a corresponding UE-specific random access preamble identifier for each SSB assigned to the target eNB so that the identifier can be used when performing random access at the target eNB. The eNB may not allocate dedicated random access preamble identifiers for all beams (depending on the current location of the UE, etc.), and some SSBs may not be allocated with dedicated random access preambles (for example, a dedicated random access preamble may be allocated to beams #2 and beams #3). If the SSB selected by the UE does not allocate a dedicated random access preamble for preamble transmission, the UE randomly selects a contention-based random access preamble for random access. For example, in the figure, after the UE is located in beam #1 and performs random access for the first time but fails, the UE can be located in beam #3 to transmit a dedicated preamble when the random access preamble is transmitted again. That is, even in one random access procedure, if preamble retransmission occurs, the contention-based random access procedure and the contention-free random access procedure may be mixed, depending on whether a dedicated random access preamble is allocated to the selected SSB for each preamble transmission.

[0044] Figure 1D A contention-based four-step random access procedure according to an embodiment of the present disclosure is shown, wherein a UE performs a contention-based four-step random access procedure with respect to a base station, which can be performed in initial access, reaccess, handover, and various other situations requiring random access.

[0045] In order to access the base station 1d-03, the UE 1d-01 Figure 1C A PRACH is selected, and a random access preamble is sent through the corresponding PRACH (operation 1d-11). It may happen that one or more UEs send random access preambles simultaneously through PRACH resources. PRACH resources may span a subframe, or may use only some symbols in a subframe. Information about PRACH resources is included in the system information broadcast by the base station, and accordingly, the UE can identify the time / frequency resources used to send the preamble. In addition, the random access preamble is a specific sequence specially designed to be receivable even when sent before being fully synchronized with the base station, and there may be multiple preamble identifiers (indexes) according to the standard. If there are multiple preamble identifiers, the preamble sent by the UE may be a preamble randomly selected by the UE, or a specific preamble specified by the base station.

[0046] After receiving the preamble, the base station may send a random access response (hereinafter referred to as "RAR") message (this is also referred to as Msg2) to the UE in response to the preamble (operation 1d-21). The RAR message includes identification information of the preamble used in operation 1d-11, uplink transmission timing correction information, uplink resource allocation information for subsequent operations (i.e., operation 1d-31), and temporary UE identifier information. Sending the identifier information of the preamble to announce the RAR message may include a response to the corresponding preamble and, for example, when multiple UEs send different preambles to attempt random access in operation 1d-11, in response to which preamble the RAR message is sent. The uplink resource allocation information included in the response to the corresponding preamble is detailed information about the resources used by the UE in operation 1d-31, and includes the physical location and size of the resources, the modulation and coding scheme used during transmission, and power adjustment information during transmission. The temporary UE identifier information is a value transmitted for use because if the UE having transmitted the preamble performs initial access, the UE does not include an identifier allocated by the base station for communication with the base station.

[0047] At the same time, the RAR message may include not only (multiple) responses to each of the preambles, but may also optionally include a backoff indicator (BI). The backoff indicator indicates a value that is sent to randomly delay transmission according to the value of the backoff indicator, rather than immediately retransmitting the preamble when the random access preamble needs to be retransmitted due to unsuccessful random access. More specifically, if the UE does not receive the RAR correctly, or if the contention resolution described later is not correctly implemented, the random access preamble should be retransmitted. Here, the value indicated by the backoff indicator may be indicated by the index value of the following table (Table 1), the UE selects a random value from 0 to the value indicated by the index value, and after a period of time equal to this value, the UE retransmits the random access preamble. For example, if the base station indicates 5 (ie, 60ms) as the BI value, and the UE randomly selects a value of 23ms from 0 to 60ms, the selected value is stored in a parameter named PREAMBLE_BACKOFF, and the UE performs the process of retransmitting the preamble after a period of 23ms. If the backoff indicator is not sent, and if random access is not successfully performed and thus the random access preamble needs to be retransmitted, the UE immediately sends the random access preamble.

[0048]

Table 1

[0049] index Backoff parameter value (ms) 0 5 1 10 2 20 3 30 4 40 5 60 6 80 7 120 8 160 9 240 10 320 11 480 12 960 13 1920 14 reserve 15 reserve

[0050] The RAR message needs to be sent within a predetermined time period starting from a predetermined time period after the preamble is sent, and the time period is called a "RAR window". The RAR window starts at a time point when a predetermined time period has passed after the first preamble is sent. The predetermined time period may have a subframe unit (1ms) or a value smaller than it. In addition, the length of the RAR window may be a predetermined value set by the base station for each PRACH resource or at least one PRACH resource in the system information message broadcast by the base station. At the same time, when sending a RAR message, the base station schedules the RAR message through the PDCCH and scrambles the corresponding scheduling information using a random access radio network temporary identifier (RA-RNTI). The RA-RNTI is mapped to the PRACH resource used to send the message 1d-11, and the UE that has sent the preamble via a specific PRACH resource attempts to receive the PDCCH based on the corresponding RA-RNTI and determine whether there is a corresponding RAR message. That is, if the RAR message is a response to the preamble sent by the UE in operation 1d-11, as shown in this example figure, the RA-RNTI for the scheduling information of the RAR message may include information about the transmission performed in operation 1d-11. To this end, the calculation formula of RA-RNTI is as follows:

[0051] RA-RNTI=1+s_id+14*t_id+14*80*f_id+14*80*8*ul_carrier_id

[0052] Here, s_id represents the index of the first OFDM symbol corresponding to the preamble transmission opportunity in operation 1d-11, and its value is 0≤s_id<14 (i.e., the maximum number of OFDM in a time slot). Further, t_id represents the index corresponding to the first time slot in which the preamble transmission opportunity in operation 1d-11 starts, and its value is 0≤t_id<80 (i.e., the maximum number of time slots in a system frame (10ms)). In addition, f_id represents the sequential position of the PRACH resource in the frequency domain through which the preamble transmission opportunity in operation 1d-11 passes, and its value is 0≤f_id<8 (i.e., the maximum number of PRACHs in the frequency domain in the same time period). In addition, ul_carrier_id is a factor used to distinguish whether the uplink through which the preamble code is transmitted is a normal uplink (NUL) (in this case, the value of ul_carrier_id is 0) or a supplementary uplink (SUL) (in this case, the value of ul_carrier_id is 1) when two carriers are used as uplinks associated with one cell.

[0053] After receiving the RAR message, the UE sends different messages via the resources allocated by the RAR message according to the above-mentioned various purposes (operation 1d-31). Here, the third message sent in this example diagram can be called Msg3 (that is, the preamble in operation 1d-11 or 1d-13 is also called Msg1, and the RAR in operation 1d-21 is also called Msg2). Examples of Msg3 sent by the UE may include an RRCSetupRequest message as an RRC layer message in the case of initial access, an RRCReestablishmentRequest message in the case of reaccess, and an RRCReconfigurationComplete message in the case of switching. Alternatively, a buffer status report (BSR) message for resource request may be sent.

[0054] Thereafter, in the case of initial transmission (i.e., if Msg3 does not include the base station identifier information previously allocated to the UE, etc.), the UE may receive a contention resolution message from the base station (operation 1d-41). The content resolution message includes the same content as that transmitted by the UE through Msg3. Therefore, even if a plurality of UEs select the same preamble in operation 1d-11 or 1d-13, it is possible to notify in which UE the contention resolution message is transmitted.

[0055] Figure 1E The process of the UE performing a two-step random access procedure on the base station is shown.

[0056] As above Figure 1D As described in , conventional contention-based random access requires at least four steps, and if an error occurs in one step, the process may be further delayed. Accordingly, it is conceivable to simplify the random access process into a two-step process.

[0057] To this end, the UE sequentially sends the preamble Msg1 1e-11 (corresponding to 1d-11) and Msg3 1e-13 (corresponding to 1d-31) in the four-step random access process, thereby sending MsgA 1e-15. Thereafter, the base station having received MsgA sends MsgB1e-19, which includes information of Msg2 (RAR) (corresponding to 1d-21) and Msg4 (corresponding to 1d-41) in the four-step random access process. Therefore, the random access process can be reduced.

[0058] Here, when MsgA is displayed in the time domain, MsgA may include PRACH resources 1e-21 for Msg1 transmission, PUSCH resources 1e-23 for Msg3 transmission, and gap resources 1e-22 for solving interference problems that may occur in the process of transmitting to the PUSCH resources. In addition, Msg3 includes information related to Msg1, and therefore it can be seen that Msg3 is transmitted by the UE that transmitted the predetermined preamble (Msg1).

[0059] Upon receiving both Msg1 and Msg3 included in MsgA, the base station transmits MsgB to the UE (operation 1e-19). Here, MsgB may include the above-mentioned BI.

[0060] Meanwhile, if a conflict occurs due to sending multiple MsgA in operation 1e-15, it may happen that the base station receives only the (multiple) Msg1 included in MsgA and cannot receive Msg3. Here, the base station may send the above-mentioned Msg2 (operation 1e-33) to the UE without sending MsgB (operation 1e-19), and the process may be changed to the four-step random access process described in FIG. D, thereby performing the remaining random access process.

[0061] In addition, in the case where the base station receives MsgA, multiple Msg1 receptions and only one Msg3 reception may occur. Here, the base station can send a response to the UE from which both Msg1 and Msg3 have been received (i.e., MsgB) (operation 1e-19) and a response to only Msg1 (i.e., Msg2) (operation 1e-33) to the UE. Different responses may be included in the same message or in different messages (operation 1e-19) (operation 1e-33). In the case of responding with different messages as shown in this figure, the base station enables an indicator to be included in the PDCCH (operation 1e-17) (operation 1e-31) for scheduling MsgB or Msg2, notifying the UE whether the scheduled message is MsgB or Msg2, and enabling the UE to decode correctly. Alternatively, the RA-RNTI value used to scramble the PDCCH can be distinguished by using different values. Here, an identifier for determining whether MsgB is included is added to the calculation of the RA-RNTI. Each of the MsgB or Msg2 messages may include the above-mentioned BI value. Thereafter, if the random access is unsuccessful, the UE needs to use the BI value included in the message to determine whether to delay the preamble transmission.

[0062] In addition, if the UE has not established a connection with the base station (for example, in order to switch from IDLE to CONNECTED), and therefore MsgA includes common control channel (CCCH) related messages (such as RRCSetupRequest, RRCResumeRequest, RRCReestablishmentRequest, RRCSystemInfoRequest and other messages of the RRC layer), the content in MsgB includes the uplink transmission timing information (timing advance command (TAC)) sent through the above-mentioned Msg2, the UE temporary identifier (temporary C-RNTI) that the UE will use in the base station in the future, and the contention resolution related information (UE contention resolution identity) sent through Msg4. In addition, if the UE is already connected to the base station and therefore a C-RNTI MAC CE including the UE's identifier information has been sent through MsgA, then MsgB is a message by which the base station sends resource allocation to the UE using the corresponding UE's identifier (C-RNTI) via PDCCH. At the same time, as mentioned above Figure 1D As described in , a UE performs random access for various purposes.

[0063] For example, the UE may perform random access to send a message for establishing a connection when the UE is not yet connected to the base station, or send a message for restoring the connection when the UE and the base station are connected but the connection fails due to an error. The above-mentioned message is a message belonging to a common control channel (CCCH). Control messages belonging to the CCCH include RRCSetupRequest (when switching from idle mode (RRC_IDLE) to connected mode), RRCResumeRequest (when switching from inactive mode (RRC_INACTIVE) to connected mode), RRCReestablishmentRequest (when restoring the connection), RRCSystemInfoRequest (when requesting system information to be broadcast by the base station), etc. As described above, if the UE is not connected to the base station and therefore the CCCH is included in the above-mentioned MsgA, the content in MsgB includes the uplink transmission timing information (timing advance command (TAC)) sent by the above-mentioned Msg2, the temporary identifier (temporary C-RNTI) of the UE to be used in the base station in the future, and the contention resolution related information (UE contention resolution identity) sent by Msg4.

[0064] At the same time, when the UE normally accesses the base station, the UE can send or receive messages belonging to the dedicated control channel (DCCH) and the dedicated traffic channel (DTCH) in the connected mode (RRC_CONNECTED). In conjunction with the message sent by the UE, the UE sends a "buffer status report (BSR)" message to inform the UE that it currently includes data to be sent to the base station via the uplink to request uplink resource allocation. To this end, the base station can allocate dedicated PUCCH resources for sending a "scheduling request (SR)" regarding a specific logical channel to the UE. Accordingly, when the base station receives the SR from the UE via the PUCCH, it can allocate uplink resources for BSR transmission, and when the BSR is sent via the corresponding uplink resources, the base station can identify the UE and provide uplink resource allocation for the data.

[0065] On the other hand, if the base station does not allocate the SR to a specific logical channel (a logical concept divided according to the types of control and general data), or if even if the base station performs the allocation of the SR and the SR has been sent the maximum number of SR transmissions, the BSR cannot be sent due to the lack of uplink resources, the UE can perform random access and send the BSR through Msg3.

[0066] Accordingly, when the UE accesses the base station and then configures each logical channel for sending data belonging to the logical channel dedicated control channel (DCCH) and dedicated traffic channel (DTCH), if the UE performs random access to perform transmission of the corresponding logical channel, the UE sends a C-RNTI MAC CE including UE identifier information through MsgA to notify that the subject performing the random access is the UE. In this case, MsgB is a message by which the base station sends resource allocation to the corresponding UE using the identifier (C-RNTI) of the corresponding UE via PDCCH.

[0067] Figure 1F Embodiment 1 is illustrated, which is related to a method for determining whether to use BI information included in a message (Msg2 or MsgB) when a UE performs a two-step random access according to an embodiment of the present disclosure.

[0068] The UE receives configuration information related to random access from the base station currently residing on it or accessing it through an RRC layer message (operation 1f-03). The RRC layer message can be sent as a system information message (SIB) broadcast by the base station to all UEs in the cell, or can be sent only to the corresponding UE in conjunction with the connected UE through an RRCReconfiguration message. The configuration information related to random access includes configuration information for a PRACH capable of sending a random access preamble (Msg1) (i.e., resources for a four-step random access procedure) and configuration information for a channel capable of sending MsgA (i.e., resources for a two-step random access procedure), and the PRACH resources for the four-step random access procedure and the PRACH resources in MsgA for the two-step random access procedure can be configured independently of each other, or configured to be shared. The configuration of shared PRACH resources indicates that a UE performing a four-step random access procedure and a UE performing a two-step random access procedure can send a random access preamble to the same PRACH resource. However, in this case, since the UE randomly selects a random access preamble within a predetermined configuration, the preamble index to be used may be the same or different.

[0069] Thereafter, the UE triggers a random access procedure (operation 1f-05). The triggering of the random access procedure may occur in order to send a CCCH for the purpose of transitioning from an idle mode to a connected mode as described above, may occur for beam failure recovery, or may occur in scenarios such as switching. Here, if the base station provides two-step random access resources and the UE supports two-step random access, the UE may determine whether to perform a two-step random access or a fourth-step random access according to a predetermined condition (operation 1f-07). That is, if the UE determines to perform a two-step random access, then in order to perform MsgA transmission, PRACH and PUSCH transmissions are performed on resources capable of transmitting MsgA, and if the UE determines to perform a four-step random access, then in order to perform Msg1 transmission, a preamble transmission is performed on PRACH resources capable of transmitting Msg1. The predetermined condition may be exemplified as, for example, performing a two-step random access procedure when the strength of the signal received from the base station is greater than a threshold indicated by the base station.

[0070] Accordingly, if the UE determines to perform four-step random access, the UE receives only Msg2 (operation 1f-21). If the base station sends Msg2 by including the BI value therein, the PREAMBLE_BACKOFF value is determined according to the corresponding value (operation 1f-23). ​​Thereafter, the above-mentioned Msg3 transmission and Msg4 reception are performed (operation 1f-31), and if the random access is not successfully completed, the UE determines whether to attempt to retransmit the preamble code, and after a delay time equal to the determined PREAMBLE_BACKOFF value, the random access preamble code transmission is performed again (operation 1f-07).

[0071] If the UE determines to perform two-step random access, the UE may receive Msg2 and / or MsgB after sending MsgA (operation 1f-11). This is because, as in the above example, when multiple UEs send MsgA, if a scenario occurs in which the base station only receives PRACH due to a conflict in PUSCH transmission, the base station may respond to this reception through Msg2. Accordingly, a scenario may occur in which the base station sends both Msg2 and MsgB, and a scenario in which the BI is included in both Msg2 and MsgB can also be considered here. This may occur in a scenario in which four-step random access and two-step random access share PRACH resources. That is, in this scenario, the BI sent through Msg2 is for the UE that performs four-step random access, and the BI sent through MsgB is for the UE that performs two-step random access. Accordingly, if the UE sends MsgA, and then if the UE receives both MsgB and Msg2 in response to the corresponding MsgA transmission, the UE determines the PREAMBLE_BACKOFF value according to the BI value included in MsgB (operation 1f-13). In addition, if the UE only receives Msg2, the UE configures the PREAMBLE_BACKOFF value to 0 even if the BI is included in the message.

[0072] Thereafter, the above-mentioned Msg3 sending and Msg4 receiving are performed (operation 1f-31), and if the random access is not successfully completed, the UE determines whether to attempt to retransmit the preamble code, and after a delay time equal to the determined PREAMBLE_BACKOFF value, performs the random access preamble code sending again (operation 1f-07).

[0073] Figure 1G Embodiment 2 is shown, which is related to a method for determining whether to use BI information included in a message (Msg2 or MsgB) when a UE performs a two-step random access according to an embodiment of the present disclosure.

[0074] The UE receives configuration information related to random access from the base station currently residing on it or accessing it through an RRC layer message (operation 1g-03). The RRC layer message can be sent as a system information message (SIB) broadcast by the base station to all UEs in the cell, or can be sent only to the corresponding UE in conjunction with the connected UE through an RRCReconfiguration message. The configuration information related to random access includes configuration information for a PRACH capable of sending a random access preamble (Msg1) (i.e., resources for a four-step random access procedure) and configuration information for a channel capable of sending MsgA (i.e., resources for a two-step random access procedure), etc., wherein the PRACH resources for the four-step random access procedure and the PRACH resources in MsgA for the two-step random access procedure can be configured independently of each other, or configured to be shared. The configuration of shared PRACH resources indicates that a UE performing a four-step random access procedure and a UE performing a two-step random access procedure can send a random access preamble to the same PRACH resource. However, in this case, since the UE randomly selects a random access preamble within a predetermined configuration, the preamble index used may be the same or different.

[0075] Thereafter, the UE triggers a random access procedure (operation 1g-05). The triggering of the random access procedure may occur in order to send a CCCH for the purpose of transitioning from an idle mode to a connected mode as described above, may occur for beam failure recovery, or may occur in scenarios such as handover. Here, if the base station provides two-step random access resources and the UE supports two-step random access, the UE may determine whether to perform two-step random access or a fourth-step random access according to a predetermined condition (operation 1g-07). That is, if the UE determines to perform two-step random access, then for MsgA transmission, PRACH and PUSCH transmissions are performed on resources capable of sending MsgA, and if the UE determines to perform four-step random access, then for Msg1 transmission, preamble transmissions are performed on PRACH resources capable of sending Msg1. The predetermined condition may be exemplified as, for example, when the strength of a signal received from the base station is greater than a threshold indicated by the base station, performing a two-step random access procedure.

[0076] Accordingly, if the UE determines to perform four-step random access, the UE receives only Msg2 (operation 1g-21). If the base station sends Msg2 by including the BI value therein, the PREAMBLE_BACKOFF value is determined according to the corresponding value (operation 1g-23). ​​Thereafter, the above-mentioned Msg3 transmission and Msg4 reception are performed (operation 1g-31), and if the random access is not successfully completed, the UE determines whether to attempt to retransmit the preamble code, and after a delay time equal to the determined PREAMBLE_BACKOFF value, the random access preamble code transmission is performed again (operation 1g-07).

[0077] If the UE determines to perform two-step random access, the UE may receive Msg2 and / or MsgB after sending MsgA (operation 1g-11). This is because, as in the above example, when multiple UEs send MsgA, if a scenario occurs in which the base station only receives PRACH due to a conflict in PUSCH transmission, the base station may respond to this reception through Msg2. Accordingly, a scenario may occur in which the base station sends both Msg2 and MsgB, and a scenario in which BI is included in both Msg2 and MsgB can also be considered here. This may occur in a scenario in which four-step random access and two-step random access share PRACH resources. Accordingly, if PRACH resources are shared in the four-step random access process and the two-step random access process, the Msg2 response is sent to both the UE that has performed two-step random access and the UE that has performed four-step random access. Therefore, if the base station is to send the BI value to the UE that has performed the two-step random access, the BI value transmission is performed through MsgB, and even if the UE receives both Msg2 and MsgB, the value of PREAMBLE_BACKOFF is determined according to the BI value included in MsgB (operation 1g-17). In addition, if the UE receives only Msg2, even if the BI is included in the message, the UE configures the PREAMBLE_BACKOFF value to 0.

[0078] However, if PRACH resources are not shared in the four-step random access procedure and the two-step random access procedure, and PRACH resources are configured only for the two-step random access, both Msg2 and MsgB transmitted with respect to the corresponding MsgA are used for the UE that has performed the two-step random access. Therefore, the UE determines the PREAMBLE_BACKOFF value according to the BI value last received from Msg2 or MsgB (operation 1g-15).

[0079] Thereafter, the above-mentioned Msg3 sending and Msg4 receiving are performed (operation 1g-31), and if the random access is not successfully completed, the UE determines whether to attempt to retransmit the preamble code, and after a delay time equal to the determined PREAMBLE_BACKOFF value, performs random access preamble code sending again (operation 1g-07).

[0080] Figure 1H Embodiment 3 is shown, which is related to a method for determining whether to use BI information included in a message (Msg2 or MsgB) when a UE performs a two-step random access according to an embodiment of the present disclosure.

[0081] The UE receives configuration information related to random access from the base station currently residing on it or accessing it through an RRC layer message (operation 1h-03). The RRC layer message can be sent as a system information message (SIB) broadcast by the base station to all UEs in the cell, or can be sent only to the corresponding UE in conjunction with the connected UE through an RRCReconfiguration message. The configuration information related to random access includes configuration information for a PRACH capable of sending a random access preamble (Msg1) (i.e., resources for a four-step random access procedure) and configuration information for a channel capable of sending MsgA (i.e., resources for a two-step random access procedure), etc., wherein the PRACH resources used for the four-step random access procedure and the PRACH resources in MsgA for the two-step random access procedure can be configured independently of each other, or configured to be shared. The configuration of shared PRACH resources indicates that a UE performing a four-step random access procedure and a UE performing a two-step random access procedure can send a random access preamble to the same PRACH resource. However, in this case, since the UE randomly selects a random access preamble within a predetermined configuration, the preamble indexes used may be the same or different.

[0082] Thereafter, the UE triggers a random access procedure (operation 1h-05). The triggering of the random access procedure may occur in order to send a CCCH for the purpose of transitioning from an idle mode to a connected mode as described above, may occur for beam failure recovery, or may occur in scenarios such as switching. Here, if the base station provides two-step random access resources and the UE supports two-step random access, the UE may determine whether to perform a two-step random access or a fourth-step random access according to a predetermined condition (operation 1h-07). That is, if the UE determines to perform a two-step random access, then for MsgA transmission, PRACH and PUSCH transmissions are performed on resources capable of sending MsgA, and if the UE determines to perform a four-step random access, then for Msg1 transmission, a preamble code transmission is performed on PRACH resources capable of sending Msg1. The predetermined condition may be exemplified as, for example, performing a two-step random access procedure when the strength of a signal received from the base station is greater than a threshold indicated by the base station.

[0083] Accordingly, if the UE determines to perform four-step random access, the UE receives only Msg2 (operation 1h-21). If the base station sends Msg2 by including the BI value therein, the PREAMBLE_BACKOFF value is determined according to the corresponding value (operation 1h-23). ​​Thereafter, the above-mentioned Msg3 transmission and Msg4 reception are performed (operation 1h-31), and if the random access is not successfully completed, the UE determines whether to attempt to retransmit the preamble, and after a delay time equal to the determined PREAMBLE_BACKOFF value, the random access preamble transmission is performed again (operation 1h-07).

[0084] If the UE determines to perform two-step random access, the UE may receive Msg2 and / or MsgB after sending MsgA (operation 1h-11). This is because, as in the above example, when multiple UEs send MsgA, if a scenario occurs in which the base station only receives PRACH due to a conflict in PUSCH transmission, the base station may respond to this reception through Msg2. Accordingly, a scenario may occur in which the base station sends both Msg2 and MsgB, and a scenario in which the BI is included in both Msg2 and MsgB can also be considered here. Accordingly, if the UE sends MsgA, and then if the UE receives both MsgB and Msg2 in response to the corresponding MsgA transmission, the UE determines the PREAMBLE_BACKOFF value based on the BI value last received from Msg2 or MsgB (operation 1h-15). Here, it is assumed that the base station configures the BI value included in Msg2 and MsgB sent in response to the corresponding MsgA transmission to the same value, and sends the same value.

[0085] Thereafter, the above-mentioned Msg3 sending and Msg4 receiving are performed (operation 1h-31), and if the random access is not successfully completed, the UE determines whether to attempt to retransmit the preamble code, and after a delay time equal to the determined PREAMBLE_BACKOFF value, performs the random access preamble code sending again (operation 1h-07).

[0086] Fig. 1I The block configuration of a UE according to an embodiment of the present disclosure is shown.

[0087] Reference Fig. 1I , the UE includes a radio frequency (RF) processor 1i-10, a baseband processor 1i-20, a storage device 1i-30 and a controller 1i-40.

[0088] The RF processor 1i-10 performs functions for sending / receiving signals through a wireless channel, such as signal band conversion, amplification, etc. That is, the RF processor 1i-10 up-converts the baseband signal provided by the baseband processor 1i-20 into an RF band signal, transmits it through an antenna, and down-converts the RF band signal received through the antenna into a baseband signal. For example, the RF processor 1i-10 may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), etc. Although Fig. 1IOnly one antenna is shown in the figure, but the UE may include multiple antennas. In addition, the RF processor 1i-10 may include multiple RF chains. In addition, the RF processor 1i-10 may perform beamforming. For beamforming, the RF processor 1i-10 may adjust the phase and amplitude of each of the signals sent / received through multiple antennas or antenna elements.

[0089] The baseband processor 1i-20 performs the conversion function between the baseband signal and the bit string according to the physical layer specification of the system. For example, during the data transmission process, the baseband processor 1i-20 encodes and modulates the transmission bit string to generate complex symbols. In addition, during data reception, the baseband processor 1i-20 demodulates and decodes the baseband signal provided from the RF processor 1i-10 to reconstruct the received bit string. For example, when following the orthogonal frequency division multiplexing (OFDM) scheme, during the data transmission process, the baseband processor 1i-20 encodes and modulates the transmission bit string to generate complex symbols, maps the complex symbols to subcarriers, and then configures the OFDM symbols through an inverse fast Fourier transform (IFFT) operation and a cyclic prefix (CP) insertion. In addition, during the data reception process, the baseband processor 1i-20 divides the baseband signal provided by the RF processor 1i-10 into units of OFDM symbols, reconstructs the signal mapped to the subcarriers through a fast Fourier transform (FFT) operation, and then reconstructs the received bit string through demodulation and decoding.

[0090] The baseband processor 1i-20 and the RF processor 1i-10 send and receive signals as described above. Therefore, the baseband processor 1i-20 and the RF processor 1i-10 can be referred to as a transmitter, a receiver, a transceiver or a communication unit. In addition, at least one of the baseband processor 1i-20 or the RF processor 1i-10 may include a plurality of communication modules to support a variety of different radio access technologies. In addition, at least one of the baseband processor 1i-20 and the RF processor 1i-10 may include different communication modules to process signals of different frequency bands. For example, different wireless access technologies may include wireless LANs (e.g., IEEE 802.11), cellular networks (e.g., LTE), etc. In addition, different frequency bands may include ultra-high frequency (SHF) (e.g., 2.5Ghz, 5Ghz) bands and millimeter wave (e.g., 60GHz) bands.

[0091] The storage device 1i-30 stores data used for the operation of the UE, such as basic programs, applications, and configuration information. Specifically, the storage device 1i-30 can store information about a wireless LAN node configured to perform wireless communication by using a wireless LAN access technology. In addition, the storage device 1i-30 provides the stored data at the request of the controller 1i-40.

[0092] The controller 1i-40 controls the overall operation of the UE. For example, the controller 1i-40 sends / receives signals through the baseband processor 1i-20 and the RF processor 1i-10. In addition, the controller 1i-40 records and reads data in the storage device 1i-30. To this end, the controller 1i-40 may include at least one processor. For example, the controller 1i-40 may include a communication processor (CP) configured to perform communication control and an application processor (AP) configured to control a higher layer such as an application. According to one embodiment of the present disclosure, the controller 1i-40 includes a multi-connection processor 1i-42, which is configured to perform processing for operating in a multi-connection mode. For example, the controller 1i-40 may control the UE to perform Figure 1E The operation process of the UE is shown.

[0093] The controller 1i-40 according to an embodiment of the present disclosure determines whether to use the BI already received from the message from among the received BI values ​​if two-step random access is triggered, thereby determining the BI value to be used when retransmitting MsgA or Msg1.

[0094] Figure 2 The structure of a UE according to an embodiment of the present disclosure is shown.

[0095] Reference Figure 2 , the UE may include a transceiver 210, a controller 220, and a storage device 230. In the present disclosure, the controller may be defined as a circuit, an application specific integrated circuit, or at least one processor.

[0096] The transceiver 210 may transmit a signal to another network or receive a signal from another network. The transceiver 210 may receive system information, for example, from a base station, and may receive a synchronization signal or a reference signal.

[0097] According to an embodiment proposed in the present disclosure, the controller 220 can control the overall operation of the UE. For example, the controller 220 can control the signal flow between the blocks to Figures 1A to 1I For example, when using the two-step random access according to the embodiment of the present disclosure, the controller 220 may perform an application backoff method.

[0098] The storage device 230 may store at least one of information transmitted or received by the transceiver 210 and information generated by the controller 220. For example, the storage device 230 may store information required to use the two-step random access according to the above-described embodiment.

[0099] Figure 3 The structure of a base station according to an embodiment of the present disclosure is shown.

[0100] Reference Figure 3, the base station may include a transceiver 310, a controller 320, and a storage device 330. In the present disclosure, the controller may be defined as a circuit, an application specific integrated circuit, or at least one processor.

[0101] The transceiver 310 may transmit a signal to another network or receive a signal from another network. The transceiver 310 may transmit system information to, for example, a UE, and may transmit a synchronization signal or a reference signal.

[0102] According to an embodiment proposed in the present disclosure, the controller 320 can control the overall operation of the base station. For example, the controller 320 can control the signal flow between the blocks to Figures 1A to 1I Specifically, when using the two-step random access according to the embodiment of the present disclosure, the controller 320 may perform an application backoff method.

[0103] The storage device 330 may store at least one of information transmitted or received by the transceiver 310 and information generated by the controller 320. For example, the storage device 330 may store information required to use the two-step random access according to the above-described embodiment.

[0104] The methods disclosed in the claims and / or the methods according to the various embodiments described in the present disclosure may be implemented by hardware, software, or a combination of hardware and software.

[0105] When these methods are implemented by software, a computer-readable storage medium for storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors in an electronic device. At least one program may include instructions for causing an electronic device to perform a method according to a plurality of embodiments of the present disclosure as defined in the accompanying claims and / or disclosed herein.

[0106] The program (software module or software) can be stored in a non-volatile memory, including random access memory and flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic disk storage device, magnetic disk-ROM (CD-ROM), digital versatile disk (DVD), or other types of optical storage devices or tapes. Alternatively, any combination of some or all of them can form a memory storing the program. In addition, a plurality of such memories can be included in an electronic device.

[0107] In addition, the program can be stored in an attachable storage device that can access the electronic device through a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WLAN), and a storage area network (SAN) or a combination thereof. Such storage devices can access the electronic device via an external port. In addition, a separate storage device on a communication network can access the portable electronic device.

[0108] In the above detailed embodiments of the present disclosure, the elements included in the present disclosure are indicated in the singular or plural according to the detailed embodiments presented. However, for the convenience of description, the singular form or the plural form is appropriately selected according to the presented situation, and the present disclosure is not limited to the elements represented in the singular or plural. Therefore, the elements represented in the plural may also include a single element, or the elements represented in the singular may also include multiple elements.

[0109] Although specific embodiments have been described in the detailed description of the present disclosure, various modifications and changes may be made thereto without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the embodiments but should be defined by the appended claims and their equivalents.

Claims

1. A method for performing random access by a terminal in a wireless communication system, the method comprising: receiving, from a base station, a threshold value related to determination of a random access type and random access related information; Determine, based on the threshold value received from the base station and the strength of the received signal, that the random access type is one of a two-step random access type and a four-step random access type; Based on the determined random access type and the random access related information, sending a signal related to a first preamble for random access to the base station, wherein the signal related to the first preamble for random access is sent based on a common resource for a two-step random access type and a four-step random access type; In a case where the determined random access type is the two-step random access type, in Msg B according to the two-step random access type and Msg 2 according to the four-step random access type, identifying a backoff indicator included in Msg B; In a case where the determined random access type is the four-step random access type, in the Msg B and the Msg2, identifying a backoff indicator included in the Msg 2; and Based on the identified backoff indicator, a signal associated with a second preamble is sent to the base station.

2. The method of claim 1 , wherein sending the signal associated with the second preamble comprises: In a case where the determined random access type is the two-step random access type, sending the signal related to the second preamble to the base station after a backoff time corresponding to a backoff indicator included in Msg B; as well as In a case where the determined random access type is the four-step random access type, the signal related to the second preamble code is sent to the base station after a backoff time corresponding to a backoff indicator included in Msg 2.

3. The method according to claim 1, wherein in the case of the two-step random access type, the signal related to the first preamble code is Msg A including a preamble code and a radio resource control (RRC) request message, and wherein in the case of the four-step random access type, the signal related to the first preamble code is Msg 1.

4. The method according to claim 1, wherein determining the random access type comprises: In a case where the strength of the received signal is greater than or equal to a threshold, the random access type is determined to be the two-step random access type, and in a case where the strength of the received signal is less than the threshold, the random access type is determined to be the four-step random access type.

5. The method according to claim 1, wherein the Msg 2 includes response information about random access, and the Msg B includes information about the random access response and contention resolution related information.

6. A method for performing random access by a base station in a wireless communication system, the method comprising: sending a threshold value related to determination of a random access type and random access related information to the terminal; receiving a signal related to a first preamble used for random access from the terminal according to random access related information, wherein the signal related to the first preamble used for random access is received only together with the preamble; In a case where the signal related to the first preamble for random access is received based on a common resource for a two-step random access type and a four-step random access type, in response to the signal related to the first preamble, sending a Msg B according to a two-step random access type including a backoff indicator and a Msg 2 according to a four-step random access type including a backoff indicator to the terminal; and receiving a signal associated with a second preamble from the terminal, Wherein, in the case where the signal associated with the first preamble is used for two-step random access, the backoff indicator included in Msg B is applicable to the signal associated with the second preamble, and Wherein, in the case where the signal associated with the first preamble is used for four-step random access, the backoff indicator included in Msg 2 is applicable to the signal associated with the second preamble.

7. The method according to claim 6, wherein the Msg 2 includes response information about random access, and the Msg B includes response information about random access and contention resolution related information.

8. The method according to claim 6, wherein: In the case where the signal associated with the first preamble is for two-step random access, receiving the signal associated with the second preamble after a backoff time corresponding to a backoff indicator included in Msg B, and Wherein, in the case where the signal associated with the first preamble is for four-step random access, the signal associated with the second preamble is received after a backoff time corresponding to the backoff indicator included in Msg2.

9. A terminal in a wireless communication system, the terminal comprising: Transceiver; as well as A controller, the controller being configured to: receiving, via the transceiver, from a base station a threshold value related to determination of a random access type and random access related information, determining a random access type to be one of a two-step random access type and a four-step random access type based on the threshold value received from the base station and the strength of the received signal, Based on the determined random access type and the random access related information, sending a signal related to a first preamble for random access to the base station via a transceiver, wherein the signal related to the first preamble for random access is sent based on a common resource for a two-step random access type and a four-step random access type; In a case where the determined random access type is the two-step random access type, in Msg B according to the two-step random access type and Msg 2 according to the four-step random access type, identifying a backoff indicator included in Msg B, In a case where the determined random access type is the four-step random access type, in the Msg B and the Msg 2, identifying a backoff indicator included in the Msg 2, and A signal associated with a second preamble is transmitted to the base station via a transceiver based on the identified backoff indicator.

10. The terminal according to claim 9, wherein the controller is configured to: In a case where the determined random access type is the two-step random access type, transmitting the signal related to the second preamble code to the base station via a transceiver after a backoff time corresponding to a backoff indicator included in Msg B; and In a case where the determined random access type is the four-step random access type, the signal related to the second preamble code is transmitted to the base station via a transceiver after a backoff time corresponding to a backoff indicator included in Msg 2.

11. The terminal according to claim 9, wherein in the case of the two-step random access type, the signal related to the first preamble is Msg A including a preamble and a radio resource control (RRC) request message, and in, In case of the four-step random access type, the signal associated with the first preamble code is Msg1.

12. The terminal according to claim 9, wherein the controller is configured to determine the random access type as the two-step random access type when the strength of the received signal is greater than or equal to the threshold, and to determine the random access type as the four-step random access type when the strength of the received signal is less than the threshold.

13. The terminal according to claim 9, wherein the Msg 2 includes response information about random access, and the Msg B includes response information about random access and contention resolution related information.

14. A base station in a wireless communication system, the base station comprising: Transceiver; as well as A controller, the controller being configured to: sending, via the transceiver, to the terminal a threshold value related to determination of a random access type and random access related information, receiving, from the terminal via the transceiver, a signal related to a first preamble code used for random access according to random access related information, wherein the signal related to the first preamble code used for random access is received only together with the preamble code, In a case where the signal related to the first preamble for random access is received based on a common resource for a two-step random access type and a four-step random access type, in response to the signal related to the first preamble, a Msg B according to a two-step random access type including a backoff indicator and a Msg 2 according to a four-step random access type including a backoff indicator are transmitted to the terminal via a transceiver, and receiving a signal related to a second preamble from the terminal via a transceiver, Wherein, in the case where the signal associated with the first preamble is used for two-step random access, the backoff indicator included in Msg B is applicable to the signal associated with the second preamble, and Wherein, in the case where the signal associated with the first preamble is used for four-step random access, the backoff indicator included in Msg 2 is applicable to the signal associated with the second preamble.

15. The base station according to claim 14, wherein the Msg 2 includes response information about random access, and the Msg B includes response information about random access and contention resolution related information, in, In case the signal associated with the first preamble is used for two-step random access, receiving the signal associated with the second preamble after a backoff time corresponding to the backoff indicator included in Msg B, and Wherein, in the case where the signal associated with the first preamble is used for four-step random access, the signal associated with the second preamble is received after a backoff time corresponding to the backoff indicator included in Msg 2.

Images