WO2020197192A1 - Method for performing random access channel procedure by terminal in wireless communication system, and apparatus therefor - Google Patents

Abstract

The present disclosure provides a method for performing a random access channel (RACH) procedure by a terminal in a wireless communication system. Specifically, the method may comprise: transmitting message A including a physical random access channel (PRACH) preamble and a physical uplink shared channel (PUSCH); and receiving message B including contention resolution information, in response to the message A, wherein information on retransmission of the message A is included in a medium access control protocol data block (MAC PDU) for a random access response (RAR) related to the message B.

Description

Method for performing a random access process by a terminal in a wireless communication system and apparatus therefor

The present disclosure relates to a method for a terminal to perform a random access process in a wireless communication system and an apparatus therefor, and more particularly, to a method for a terminal to perform a two-step random access process in a wireless communication system and an apparatus therefor. About.

As more communication devices require greater communication traffic as the times flow, a next-generation 5G system, which is a wireless broadband communication improved over the existing LTE system, is required. In this next-generation 5G system, called NewRAT, communication scenarios are classified into Enhanced Mobile BroadBand (eMBB)/Ultra-reliability and low-latency communication (URLLC)/Massive Machine-Type Communications (mMTC).

Here, eMBB is a next-generation mobile communication scenario with features such as High Spectrum Efficiency, High User Experienced Data Rate, and High Peak Data Rate, and URLLC is a next-generation mobile communication scenario with features such as Ultra Reliable, Ultra Low Latency, and Ultra High Availability. And (eg, V2X, Emergency Service, Remote Control), mMTC is a next-generation mobile communication scenario with characteristics of Low Cost, Low Energy, Short Packet, and Massive Connectivity. (e.g., IoT).

The present disclosure is to provide a method for a terminal to perform a 2-step random access process and an apparatus therefor.

The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. I will be able to.

In a method for a UE to perform a Random Access Channel Procedure (RACH Procedure) in a wireless communication system according to an embodiment of the present disclosure, including a Physical Random Access Channel (PRACH) preamble and a Physical Uplink Shared Channel (PUSCH) The message A is transmitted to the base station, and in response to the message A, a message B including contention resolution information is received from the base station, and a random access response (RAR) related to the message B is received. ) May include information on the retransmission of the message A in the MAC PDU (Medium Access Control Protocol Data Block).

In this case, the information on the retransmission of the message A may include information on whether to retransmit the message A and information on the number of retransmissions of the message A.

In addition, the information on the retransmission of the message A may be indicated based on bits included in reserved bits for sub-headers in the MAC PDU.

In addition, the information on the retransmission of the message A may be used based on the fact that the RAR is not decoded by the terminal.

In addition, a single bit is used to indicate information on the retransmission of the message A, and based on the fact that the RAR is not decoded by the terminal and the value represented by the single bit is 1, the retransmission of the message A is Can be done.

In addition, a plurality of bits are used to indicate information on the retransmission of the message A, based on the fact that the RAR is not decoded by the terminal and the value indicated by the plurality of bits is not 0, the message A Retransmission of can be performed.

In addition, the number of times the message A can be retransmitted may be based on a value indicated by the plurality of bits.

An apparatus for performing a random access channel procedure (RACH Procedure) in a wireless communication system according to the present disclosure, comprising: at least one processor; And at least one memory that is operatively connected to the at least one processor and stores instructions for causing the at least one processor to perform a specific operation when executed, wherein the specific operation is PRACH (Physical Random Access Channel) Transmitting a message A including a preamble and a PUSCH (Physical Uplink Shared Channel), and in response to the message A, including receiving a message B including contention resolution information, , In a MAC PDU (Medium Access Control Protocol Data Block) for a random access response (RAR) related to the message B, information on the retransmission of the message A may be included.

In this case, the information on the retransmission of the message A may include information on whether to retransmit the message A and information on the number of retransmissions of the message A.

In addition, the information on the retransmission of the message A may be indicated based on bits included in reserved bits for sub-headers in the MAC PDU.

In addition, the information on the retransmission of the message A may be used based on the fact that the RAR is not decoded by the terminal.

In addition, a single bit is used to indicate information on the retransmission of the message A, and based on the fact that the RAR is not decoded by the terminal and the value represented by the single bit is 1, the retransmission of the message A is Can be done.

In addition, a plurality of bits are used to indicate information on the retransmission of the message A, based on the fact that the RAR is not decoded by the terminal and the value indicated by the plurality of bits is not 0, the message A Retransmission of can be performed.

In addition, the number of times the message A can be retransmitted may be based on a value indicated by the plurality of bits.

According to the present disclosure, in a wireless communication system, a terminal may perform a more appropriate 2-step random access process by utilizing a random access response (RAR).

The effects obtainable in the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those of ordinary skill in the art from the following description. will be.

1 is a diagram showing the structure of a control plane and a user plane of a radio interface protocol between a terminal and an E-UTRAN based on a 3GPP radio access network standard.

FIG. 2 is a diagram illustrating physical channels used in a 3GPP system and a general signal transmission method using them.

3 to 5 are diagrams for explaining the structure of radio frames and slots used in the NR system.

6 to 11 are diagrams for explaining a composition and a transmission method of an SS/PBCH block.

12 is a diagram illustrating an example of a random access procedure.

13 is a diagram for describing multiplexing of a Long PUCCH (Physical Uplink Control Channel) and a Short PUCCH in an NR system.

14 illustrates an ACK/NACK transmission process.

15 to 17 are views for explaining a downlink control channel (Physical Downlink Control Channel; PDCCH) in the NR system.

18 to 19 are diagrams for explaining an example of implementing specific operations of a terminal and a base station according to an embodiment of the present disclosure.

20 is a diagram showing a basic process of a 2-step RACH.

21 is a diagram illustrating messages transmitted and received in a 4-step RACH procedure along a time axis.

22 is a diagram illustrating a RAR monitoring window that serves as a reference for performing a RACH procedure.

23 is a diagram illustrating a method of indicating information on retransmission of Msg A using reserved bits of a MAC sub-header through which BI information is transmitted.

24 is a diagram illustrating a method of transmitting result information on whether decoding success or failure of a PUSCH in a 2-step RACH procedure using a single bit.

25 is a diagram illustrating an operation flow of a terminal and a base station for performing a 2-step RACH procedure based on embodiments of the present disclosure.

26 shows an example of a communication system to which embodiments of the present disclosure are applied.

27 to 30 illustrate examples of various wireless devices to which embodiments of the present disclosure are applied.

31 shows an example of a signal processing circuit to which embodiments of the present disclosure are applied.

The configuration, operation, and other features of the present invention may be easily understood by the embodiments of the present invention described below with reference to the accompanying drawings. The embodiments described below are examples in which the technical features of the present invention are applied to a 3GPP system.

Although this specification describes an embodiment of the present invention using an LTE system, an LTE-A system, and an NR system, this is an example, and the embodiment of the present invention may be applied to any communication system corresponding to the above definition.

In addition, in the present specification, the name of the base station may be used as a generic term including a remote radio head (RRH), an eNB, a transmission point (TP), a reception point (RP), a relay, and the like.

3GPP-based communication standards include downlink physical channels corresponding to resource elements carrying information originating from higher layers, and downlink corresponding to resource elements used by the physical layer but not carrying information originating from higher layers. Physical signals are defined. For example, a physical downlink shared channel (PDSCH), a physical broadcast channel (PBCH), a physical multicast channel (PMCH), a physical control format indicator channel (physical control) A format indicator channel, PCFICH), a physical downlink control channel (PDCCH), and a physical hybrid ARQ indicator channel (PHICH) are defined as downlink physical channels, and a reference signal and a synchronization signal Is defined as downlink physical signals. A reference signal (RS), also referred to as a pilot, refers to a signal of a predefined special waveform that the gNB and the UE know each other, for example, cell specific RS (RS), UE- Specific RS (UE-specific RS, UE-RS), positioning RS (positioning RS, PRS), and channel state information RS (channel state information RS, CSI-RS) are defined as downlink reference signals. The 3GPP LTE/LTE-A standard corresponds to uplink physical channels corresponding to resource elements carrying information originating from an upper layer, and resource elements used by the physical layer but not carrying information originating from an upper layer. Uplink physical signals are defined. For example, a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), and a physical random access channel (PRACH) are used as uplink physical channels. A demodulation reference signal (DMRS) for an uplink control/data signal and a sounding reference signal (SRS) used for uplink channel measurement are defined.

In the present invention, PDCCH (Physical Downlink Control CHannel) / PCFICH (Physical Control Format Indicator CHannel) / PHICH ((Physical Hybrid automatic retransmit request Indicator CHannel) / PDSCH (Physical Downlink Shared CHannel) is DCI (Downlink Control Information) / CFI ( Control Format Indicator) / Downlink ACK / NACK (ACKnowlegement / Negative ACK) / refers to a set of time-frequency resources carrying downlink data or a set of resource elements In addition, PUCCH (Physical Uplink Control CHannel) / PUSCH (Physical Uplink Shared CHannel)/PRACH (Physical Random Access CHannel) refers to a set of time-frequency resources or a set of resource elements each carrying uplink control information (UCI)/uplink data/random access signals. , PDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH allocated to or belonging to a time-frequency resource or resource element (RE), respectively, PDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH RE or PDCCH It is referred to as /PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resource.In the following, the expression that the user equipment transmits PUCCH/PUSCH/PRACH is, uplink control information/uplink data on or through PUSCH/PUCCH/PRACH /It is used in the same meaning as that of transmitting a random access signal.In addition, the expression that gNB transmits PDCCH/PCFICH/PHICH/PDSCH is on the PDCCH/PCFICH/PHICH/PDSCH, respectively. It is used in the same meaning as transmitting downlink data/control information through or through.

Hereinafter, CRS/DMRS/CSI-RS/SRS/UE-RS are allocated or configured OFDM symbols/subcarriers/REs are CRS/DMRS/CSI-RS/SRS/UE-RS symbols/carriers. It is called /subcarrier/RE. For example, an OFDM symbol to which a tracking RS (TRS) is allocated or configured is referred to as a TRS symbol, and a subcarrier to which a TRS is allocated or configured is referred to as a TRS subcarrier, and a TRS is allocated. Alternatively, the configured RE is referred to as TRS RE. In addition, a subframe configured for TRS transmission is referred to as a TRS subframe. In addition, a subframe in which a broadcast signal is transmitted is called a broadcast subframe or a PBCH subframe, and a subframe in which a synchronization signal (eg, PSS and/or SSS) is transmitted is a synchronization signal subframe or a PSS/SSS subframe. It is called. An OFDM symbol/subcarrier/RE to which PSS/SSS is assigned or configured is referred to as PSS/SSS symbol/subcarrier/RE, respectively.

In the present invention, a CRS port, a UE-RS port, a CSI-RS port, and a TRS port respectively refer to an antenna port configured to transmit a CRS, an antenna port configured to transmit a UE-RS, Refers to an antenna port configured to transmit CSI-RS and an antenna port configured to transmit TRS. The antenna ports configured to transmit CRSs can be distinguished from each other by the positions of the REs occupied by the CRS according to the CRS ports, and the antenna ports configured to transmit UE-RSs are UE -According to the RS ports, the positions of the REs occupied by the UE-RS can be distinguished from each other, and the antenna ports configured to transmit CSI-RSs are occupied by the CSI-RS according to the CSI-RS ports. It can be distinguished from each other by the location of the REs. Therefore, the term CRS/UE-RS/CSI-RS/TRS port is also used as a term to mean a pattern of REs occupied by CRS/UE-RS/CSI-RS/TRS within a certain resource area.

Now, let's look at 5G communication including the NR system.

The three main requirements areas for 5G are (1) Enhanced Mobile Broadband (eMBB) area, (2) Massive Machine Type Communication (mMTC) area, and (3) ultra-reliability and It includes a low-latency communication (Ultra-reliable and Low Latency Communications, URLLC) area.

In some use cases, multiple areas may be required for optimization, and other use cases may be focused on only one key performance indicator (KPI). 5G supports these various use cases in a flexible and reliable way.

eMBB goes far beyond basic mobile Internet access, covering rich interactive work, media and entertainment applications in the cloud or augmented reality. Data is one of the key drivers of 5G, and it may not be possible to see dedicated voice services for the first time in the 5G era. In 5G, voice is expected to be processed as an application program simply using the data connection provided by the communication system. The main reasons for the increased traffic volume are an increase in content size and an increase in the number of applications requiring high data rates. Streaming services (audio and video), interactive video and mobile Internet connections will become more widely used as more devices connect to the Internet. Many of these applications require always-on connectivity to push real-time information and notifications to the user. Cloud storage and applications are increasing rapidly in mobile communication platforms, which can be applied to both work and entertainment. And, cloud storage is a special use case that drives the growth of the uplink data rate. 5G is also used for remote work in the cloud, and requires much lower end-to-end delays to maintain a good user experience when tactile interfaces are used. Entertainment For example, cloud gaming and video streaming is another key factor that is increasing the demand for mobile broadband capabilities. Entertainment is essential on smartphones and tablets anywhere, including high mobility environments such as trains, cars and airplanes. Another use case is augmented reality and information retrieval for entertainment. Here, augmented reality requires very low latency and an instantaneous amount of data.

In addition, one of the most anticipated 5G use cases relates to the ability to seamlessly connect embedded sensors in all fields, i.e. mMTC. By 2020, potential IoT devices are expected to reach 20.4 billion. Industrial IoT is one of the areas where 5G plays a major role in enabling smart cities, asset tracking, smart utilities, agriculture and security infrastructure.

URLLC includes new services that will transform the industry with ultra-reliable/low-latency links such as self-driving vehicles and remote control of critical infrastructure. The level of reliability and delay is essential for smart grid control, industrial automation, robotics, drone control and coordination.

Next, a number of examples of use in 5G communication systems including NR systems will be described in more detail.

5G can complement fiber-to-the-home (FTTH) and cable-based broadband (or DOCSIS) as a means of providing streams rated at hundreds of megabits per second to gigabits per second. This high speed is required to deliver TVs in 4K or higher (6K, 8K and higher) resolutions as well as virtual and augmented reality. Virtual Reality (VR) and Augmented Reality (AR) applications involve almost immersive sports events. Certain application programs may require special network settings. In the case of VR games, for example, game companies may need to integrate core servers with network operators' edge network servers to minimize latency.

Automotive is expected to be an important new driving force in 5G, with many use cases for mobile communication to vehicles. For example, entertainment for passengers demands simultaneous high capacity and high mobility mobile broadband. The reason is that future users will continue to expect high-quality connections, regardless of their location and speed. Another application example in the automotive field is an augmented reality dashboard. It identifies an object in the dark on top of what the driver is looking through the front window, and displays information that tells the driver about the distance and movement of the object overlaid. In the future, wireless modules enable communication between vehicles, exchange of information between the vehicle and supporting infrastructure, and exchange of information between the vehicle and other connected devices (eg, devices carried by pedestrians). The safety system allows the driver to lower the risk of accidents by guiding alternative courses of action to make driving safer. The next step will be a remote controlled or self-driven vehicle. It is very reliable and requires very fast communication between different self-driving vehicles and between the vehicle and the infrastructure. In the future, self-driving vehicles will perform all driving activities, and drivers will be forced to focus only on traffic anomalies that the vehicle itself cannot identify. The technical requirements of self-driving vehicles call for ultra-low latency and ultra-fast reliability to increase traffic safety to levels unachievable by humans.

Smart cities and smart homes, referred to as smart society, will be embedded with high-density wireless sensor networks. A distributed network of intelligent sensors will identify the conditions for cost and energy-efficient maintenance of a city or home. A similar setup can be done for each household. Temperature sensors, window and heating controllers, burglar alarms and appliances are all wirelessly connected. Many of these sensors are typically low data rates, low power and low cost. However, for example, real-time HD video may be required in certain types of devices for surveillance.

The consumption and distribution of energy, including heat or gas, is highly decentralized, requiring automated control of distributed sensor networks. The smart grid interconnects these sensors using digital information and communication technologies to collect information and act accordingly. This information can include the behavior of suppliers and consumers, allowing smart grids to improve efficiency, reliability, economics, sustainability of production and the distribution of fuels such as electricity in an automated way. The smart grid can also be viewed as another low-latency sensor network.

The health sector has many applications that can benefit from mobile communications. The communication system can support telemedicine providing clinical care from remote locations. This can help reduce barriers to distance and improve access to medical services that are not consistently available in remote rural areas. It is also used to save lives in critical care and emergencies. A wireless sensor network based on mobile communication may provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly important in industrial applications. Wiring is expensive to install and maintain. Thus, the possibility of replacing cables with reconfigurable wireless links is an attractive opportunity for many industries. However, achieving this requires that the wireless connection operates with a delay, reliability and capacity similar to that of the cable, and its management is simplified. Low latency and very low error probability are new requirements that need to be connected to 5G.

Logistics and freight tracking are important use cases for mobile communications that enable tracking of inventory and packages from anywhere using location-based information systems. Logistics and freight tracking use cases typically require low data rates, but require a wide range and reliable location information.

1 is a diagram showing the structure of a control plane and a user plane of a radio interface protocol between a terminal and an E-UTRAN based on a 3GPP radio access network standard. The control plane refers to a path through which control messages used by a user equipment (UE) and a network to manage a call are transmitted. The user plane refers to a path through which data generated in the application layer, for example, voice data or Internet packet data, is transmitted.

The first layer, the physical layer, provides an information transfer service to an upper layer using a physical channel. The physical layer is connected to the upper medium access control layer through a transmission channel (transport channel). Data is transferred between the medium access control layer and the physical layer through the transmission channel. Data moves between the physical layers of the transmitting side and the receiving side through a physical channel. The physical channel uses time and frequency as radio resources. Specifically, a physical channel is modulated in an Orthogonal Frequency Division Multiple Access (OFDMA) scheme in downlink and a single carrier frequency division multiple access (SC-FDMA) scheme in uplink.

The medium access control (MAC) layer of the second layer provides a service to an upper layer, the Radio Link Control (RLC) layer, through a logical channel. The RLC layer of the second layer supports reliable data transmission. The function of the RLC layer may be implemented as a functional block inside the MAC. The PDCP (Packet Data Convergence Protocol) layer of the second layer performs a header compression function that reduces unnecessary control information in order to efficiently transmit IP packets such as IPv4 or IPv6 over a narrow bandwidth wireless interface.

The radio resource control (RRC) layer located at the bottom of the third layer is defined only in the control plane. The RRC layer is in charge of controlling logical channels, transmission channels, and physical channels in relation to configuration, re-configuration, and release of radio bearers. The radio bearer refers to a service provided by the second layer for data transmission between the terminal and the network. To this end, the UE and the RRC layer of the network exchange RRC messages with each other. If there is an RRC connection (RRC Connected) between the terminal and the RRC layer of the network, the terminal is in an RRC connected state (Connected Mode), otherwise it is in the RRC idle state (Idle Mode). The NAS (Non-Access Stratum) layer above the RRC layer performs functions such as session management and mobility management.

The downlink transmission channel for transmitting data from the network to the terminal includes a broadcast channel (BCH) that transmits system information, a paging channel (PCH) that transmits paging messages, and a downlink shared channel (SCH) that transmits user traffic or control messages. have. In the case of a downlink multicast or broadcast service traffic or control message, it may be transmitted through a downlink SCH or a separate downlink multicast channel (MCH). Meanwhile, as an uplink transmission channel for transmitting data from a terminal to a network, there are a random access channel (RACH) for transmitting an initial control message, and an uplink shared channel (SCH) for transmitting user traffic or control messages. It is located above the transmission channel, and the logical channels mapped to the transmission channel include BCCH (Broadcast Control Channel), PCCH (Paging Control Channel), CCCH (Common Control Channel), MCCH (Multicast Control Channel), MTCH (Multicast). Traffic Channel).

FIG. 2 is a diagram illustrating physical channels used in a 3GPP system and a general signal transmission method using them.

When the terminal is powered on or newly enters a cell, the terminal performs an initial cell search operation such as synchronizing with the base station (S201). To this end, the UE receives a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) from the base station to synchronize with the base station and obtain information such as cell ID. Thereafter, the terminal may receive a physical broadcast channel (PBCH) from the base station to obtain intra-cell broadcast information. Meanwhile, the UE may receive a downlink reference signal (DL RS) in the initial cell search step to check a downlink channel state.

After completing the initial cell search, the UE acquires more detailed system information by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to the information carried on the PDCCH. It can be done (S202).

On the other hand, when accessing the base station for the first time or when there is no radio resource for signal transmission, the terminal may perform a random access procedure (RACH) with respect to the base station (S203 to S206). To this end, the UE transmits a specific sequence as a preamble through a physical random access channel (PRACH) (S203 and S205), and a response message to the preamble through a PDCCH and a corresponding PDSCH (RAR (Random Access Response) message) In the case of contention-based RACH, a contention resolution procedure may be additionally performed (S206).

After performing the above-described procedure, the UE receives PDCCH/PDSCH (S207) and Physical Uplink Shared Channel (PUSCH)/Physical Uplink Control Channel as a general uplink/downlink signal transmission procedure. Control Channel; PUCCH) transmission (S208) may be performed. In particular, the terminal may receive downlink control information (DCI) through the PDCCH. Here, the DCI includes control information such as resource allocation information for the terminal, and different formats may be applied according to the purpose of use.

On the other hand, the control information transmitted by the terminal to the base station through the uplink or received from the base station by the terminal is a downlink/uplink ACK/NACK signal, a channel quality indicator (CQI), a precoding matrix index (PMI), a rank indicator (RI). ), etc. The terminal may transmit control information such as CQI/PMI/RI described above through PUSCH and/or PUCCH.

Meanwhile, the NR system is considering a method of using a high ultra-high frequency band, that is, a millimeter frequency band of 6 GHz or higher to transmit data while maintaining a high transmission rate to a large number of users using a wide frequency band. In 3GPP, this is used under the name NR, and in the present invention, it will be referred to as an NR system.

NR supports multiple numerology (or subcarrier spacing (SCS)) to support various 5G services. For example, when the SCS is 15 kHz, it supports a wide area in traditional cellular bands, and when the SCS is 30 kHz/60 kHz, it is dense-urban, lower latency. And a wider carrier bandwidth (wider carrier bandwidth) is supported, and when the SCS is 60 kHz or higher, a bandwidth greater than 24.25 kHz is supported to overcome phase noise.

The NR frequency band is defined as a frequency range of two types (FR1, FR2). FR1 is a sub 6GHz range, and FR2 may mean a millimeter wave (mmW) in the above 6GHz range.

Table 1 below shows the definition of the NR frequency band.

Frequency Range Designation	Corresponding frequency range	Subcarrier Spacing
FR1	410MHz- 7125MHz	15, 30, 60 kHz
FR2	24250MHz-52600MHz	60, 120, 240 kHz

3 illustrates a structure of a radio frame used in NR.

In NR, uplink and downlink transmission is composed of frames. The radio frame has a length of 10ms and is defined as two 5ms half-frames (HF). The half-frame is defined as five 1ms subframes (Subframe, SF). The subframe is divided into one or more slots, and the number of slots in the subframe depends on Subcarrier Spacing (SCS). Each slot includes 12 or 14 OFDM(A) symbols according to a cyclic prefix (CP). When a normal CP is used, each slot includes 14 symbols. When the extended CP is used, each slot includes 12 symbols. Here, the symbol may include an OFDM symbol (or CP-OFDM symbol), an SC-FDMA symbol (or DFT-s-OFDM symbol).

Table 2 exemplifies that when a normal CP is used, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary according to the SCS.

SCS (15*2^u)	N slot symb	N frame,u slot	N subframe,u slot
15KHz (u=0)	14	10	One
30KHz (u=1)	14	20	2
60KHz (u=2)	14	40	4
120KHz (u=3)	14	80	8
240KHz (u=4)	14	160	16

* N ^slot _symb : number of symbols in slot* N ^frame,u _slot : number of slots in frame

* N ^subframe,u _slot : number of slots in ^subframe

Table 3 exemplifies that when the extended CP is used, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary according to the SCS.

SCS (15*2^u)	N slot symb	N frame,u slot	N subframe,u slot
60KHz (u=2)	12	40	4

In the NR system, OFDM(A) numerology (eg, SCS, CP length, etc.) may be set differently between a plurality of cells merged into one terminal. Accordingly, the (absolute time) section of the time resource (eg, SF, slot or TTI) (for convenience, collectively referred to as TU (Time Unit)) composed of the same number of symbols may be set differently between the merged cells.

4 illustrates a slot structure of an NR frame. The slot includes a plurality of symbols in the time domain. For example, in the case of a normal CP, one slot includes 14 symbols, but in the case of an extended CP, one slot includes 12 symbols. The carrier includes a plurality of subcarriers in the frequency domain. RB (Resource Block) is defined as a plurality of (eg, 12) consecutive subcarriers in the frequency domain. The BWP (Bandwidth Part) is defined as a plurality of consecutive (P)RBs in the frequency domain, and may correspond to one numerology (eg, SCS, CP length, etc.). The carrier may contain up to N (eg, 4) BWPs. Data communication is performed through the activated BWP, and only one BWP can be activated to one terminal. Each element in the resource grid is referred to as a resource element (RE), and one complex symbol may be mapped.

5 illustrates the structure of a self-contained slot. In the NR system, a frame is characterized by a self-contained structure in which all of a DL control channel, DL or UL data, and a UL control channel can be included in one slot. For example, the first N symbols in a slot may be used to transmit a DL control channel (hereinafter, a DL control region), and the last M symbols in a slot may be used to transmit a UL control channel (hereinafter, a UL control region). N and M are each an integer of 0 or more. A resource region (hereinafter, a data region) between the DL control region and the UL control region may be used for DL data transmission or UL data transmission. As an example, the following configuration may be considered. Each section was listed in chronological order.

1.DL only configuration

2. UL only configuration

3. Mixed UL-DL configuration

-DL area + GP(Guard Period) + UL control area

-DL control area + GP + UL area

* DL area: (i) DL data area, (ii) DL control area + DL data area

* UL area: (i) UL data area, (ii) UL data area + UL control area

The PDCCH may be transmitted in the DL control region, and the PDSCH may be transmitted in the DL data region. PUCCH may be transmitted in the UL control region, and PUSCH may be transmitted in the UL data region. On the PDCCH, downlink control information (DCI), for example, DL data scheduling information, UL data scheduling information, and the like may be transmitted. In PUCCH, uplink control information (UCI), for example, positive acknowledgment/negative acknowledgment (ACK/NACK) information for DL data, channel state information (CSI) information, scheduling request (SR), and the like may be transmitted. The GP provides a time gap when the base station and the terminal switch from a transmission mode to a reception mode or a process from a reception mode to a transmission mode. Some symbols at a time point at which the DL to UL is switched in the subframe may be set as GP.

6 illustrates an SSB structure. The UE may perform cell search, system information acquisition, beam alignment for initial access, and DL measurement based on the SSB. SSB is used interchangeably with SS/PBCH (Synchronization Signal/Physical Broadcast Channel) block.

6, the SSB is composed of PSS, SSS and PBCH. The SSB is composed of 4 consecutive OFDM symbols, and PSS, PBCH, SSS/PBCH and PBCH are transmitted for each OFDM symbol. The PSS and SSS are each composed of 1 OFDM symbol and 127 subcarriers, and the PBCH is composed of 3 OFDM symbols and 576 subcarriers. Polar coding and Quadrature Phase Shift Keying (QPSK) are applied to the PBCH. The PBCH consists of a data RE and a demodulation reference signal (DMRS) RE for each OFDM symbol. There are 3 DMRS REs for each RB, and 3 data REs exist between the DMRS REs.

Cell search

Cell search refers to a process in which a UE acquires time/frequency synchronization of a cell and detects a cell identifier (eg, Physical layer Cell ID, PCID) of the cell. PSS is used to detect a cell ID within a cell ID group, and SSS is used to detect a cell ID group. PBCH is used for SSB (time) index detection and half-frame detection.

The cell search process of the terminal may be summarized as shown in Table 4 below.

	Type of Signals		Operations
1 st step	PSS	* SS/PBCH block (SSB) symbol timing acquisition* Cell ID detection within a cell ID group(3 hypothesis)
2 nd Step	SSS	* Cell ID group detection (336 hypothesis)
3 rd Step	PBCH DMRS	* SSB index and Half frame (HF) index(Slot and frame boundary detection)
4 th Step	PBCH	* Time information (80 ms, System Frame Number (SFN), SSB index, HF) * Remaining Minimum System Information (RMSI) Control resource set (CORESET)/Search space configuration
5 th Step	PDCCH and PDSCH	* Cell access information* RACH configuration

7 illustrates SSB transmission.

SSB is transmitted periodically according to the SSB period. The SSB basic period assumed by the UE during initial cell search is defined as 20 ms. After cell access, the SSB period may be set to one of {5ms, 10ms, 20ms, 40ms, 80ms, 160ms} by the network (eg, base station). At the beginning of the SSB period, a set of SSB bursts is constructed. The SSB burst set consists of a 5 ms time window (ie, half-frame), and the SSB can be transmitted up to L times in the SS burst set. The maximum number of transmissions L of the SSB may be given as follows according to the frequency band of the carrier. One slot contains at most two SSBs.

-For frequency range up to 3 GHz, L = 4

-For frequency range from 3GHz to 6 GHz, L = 8

-For frequency range from 6 GHz to 52.6 GHz, L = 64

The temporal position of the SSB candidate within the SS burst set may be defined as follows according to the SCS. The temporal position of the SSB candidate is indexed from 0 to L-1 in the temporal order within the SSB burst set (ie, half-frame) (SSB index).

-Case A-15 kHz SCS: The index of the start symbol of the candidate SSB is given as {2, 8} + 14*n. When the carrier frequency is 3 GHz or less, n=0, 1. When the carrier frequency is 3 GHz to 6 GHz, n = 0, 1, 2, 3.

-Case B-30 kHz SCS: The index of the start symbol of the candidate SSB is given as {4, 8, 16, 20} + 28*n. When the carrier frequency is 3 GHz or less, n=0. When the carrier frequency is 3 GHz to 6 GHz, n=0, 1.

-Case C-30 kHz SCS: The index of the start symbol of the candidate SSB is given as {2, 8} + 14*n. When the carrier frequency is 3 GHz or less, n=0, 1. When the carrier frequency is 3 GHz to 6 GHz, n = 0, 1, 2, 3.

-Case D-120 kHz SCS: The index of the start symbol of the candidate SSB is given as {4, 8, 16, 20} + 28*n. When the carrier frequency is greater than 6 GHz, n=0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18.

-Case E-240 kHz SCS: The index of the start symbol of the candidate SSB is given as {8, 12, 16, 20, 32, 36, 40, 44} + 56*n. When the carrier frequency is greater than 6 GHz, n = 0, 1, 2, 3, 5, 6, 7, 8.

8 illustrates that the terminal acquires information on DL time synchronization.

The UE can acquire DL synchronization by detecting the SSB. The terminal may identify the structure of the SSB burst set based on the detected SSB index, and accordingly, may detect a symbol/slot/half-frame boundary. The number of the frame/half-frame to which the detected SSB belongs can be identified using SFN information and half-frame indication information.

Specifically, the UE may obtain 10-bit SFN (System Frame Number) information from the PBCH (s0 to s9). Of the 10-bit SFN information, 6 bits are obtained from MIB (Master Information Block), and the remaining 4 bits are obtained from PBCH TB (Transport Block).

Next, the terminal may acquire 1-bit half-frame indication information (c0). When the carrier frequency is 3 GHz or less, the half-frame indication information may be implicitly signaled using PBCH DMRS. The PBCH DMRS indicates 3-bit information by using one of 8 PBCH DMRS sequences. Therefore, in the case of L=4, the SSB index is indicated among 3 bits that can be indicated using 8 PBCH DMRS sequences, and the remaining 1 bit may be used for half-frame indication.

Finally, the UE may acquire an SSB index based on the DMRS sequence and PBCH payload. SSB candidates are indexed from 0 to L-1 in time order within the SSB burst set (ie, half-frame). When L = 8 or 64, 3 bits of the LSB (Least Significant Bit) of the SSB index may be indicated using 8 different PBCH DMRS sequences (b0 to b2). When L = 64, 3 bits of the MSB (Most Significant Bit) of the SSB index are indicated through the PBCH (b3 to b5). When L = 2, the LSB 2 bits of the SSB index may be indicated using four different PBCH DMRS sequences (b0, b1). When L = 4, out of 3 bits that can be indicated by using 8 PBCH DMRS sequences, the SSB index is indicated and the remaining 1 bit may be used for half-frame indication (b2).

System information acquisition

9 illustrates a process of obtaining system information (SI). The UE may acquire AS-/NAS-information through the SI acquisition process. The SI acquisition process may be applied to a UE in an RRC_IDLE state, an RRC_INACTIVE state, and an RRC_CONNECTED state.

SI is divided into MIB (Master Information Block) and a plurality of SIB (System Information Block). The MIB and the plurality of SIBs may be further divided into a minimum SI (SI) and another SI (other SI). Here, the minimum SI may be composed of MIB and SIB 1, and includes basic information required for initial access and information for obtaining a different SI. Here, SIB 1 may be referred to as RMSI (Remaining Minimum System Information). For details, refer to the following.

-The MIB contains information/parameters related to SIB1 (SystemInformationBlockType1) reception and is transmitted through the PBCH of the SSB. In initial cell selection, the UE assumes that the half-frame with SSB is repeated in a 20ms cycle. The UE may check whether there is a CORESET (Control Resource Set) for the Type0-PDCCH common search space based on the MIB. The Type0-PDCCH common search space is a kind of PDCCH search space, and is used to transmit a PDCCH for scheduling SI messages. If there is a Type0-PDCCH common search space, the UE based on information in the MIB (e.g., pdcch-ConfigSIB1) (i) a plurality of consecutive RBs constituting CORESET and one or more consecutive symbols and (ii) PDCCH opportunity (That is, a time domain location for PDCCH reception) can be determined. When the Type0-PDCCH common search space does not exist, pdcch-ConfigSIB1 provides information on a frequency location in which SSB/SIB1 exists and a frequency range in which SSB/SIB1 does not exist.

-SIB1 includes information related to availability and scheduling (eg, transmission period, SI-window size) of the remaining SIBs (hereinafter, SIBx, x is an integer greater than or equal to 2). For example, SIB1 may inform whether SIBx is periodically broadcast or is provided by a request of a terminal through an on-demand method. When SIBx is provided by an on-demand method, SIB1 may include information necessary for the UE to perform an SI request. SIB1 is transmitted through the PDSCH, the PDCCH scheduling SIB1 is transmitted through the Type0-PDCCH common search space, and SIB1 is transmitted through the PDSCH indicated by the PDCCH.

-SIBx is included in the SI message and is transmitted through PDSCH. Each SI message is transmitted within a periodic time window (ie, SI-window).

Beam alignment

10 illustrates multi-beam transmission of SSB.

Beam sweeping means that a transmission reception point (TRP) (eg, a base station/cell) changes a beam (direction) of a radio signal according to time (hereinafter, a beam and a beam direction may be mixed). SSB may be periodically transmitted using beam sweeping. In this case, the SSB index is implicitly linked with the SSB beam. The SSB beam may be changed in units of SSB (index) or in units of SSB (index) groups. In the latter case, the SSB beam remains the same within the SSB (index) group. That is, the transmission beam echo of the SSB is repeated in a plurality of consecutive SSBs. The maximum number of transmissions L of the SSB in the SSB burst set has a value of 4, 8 or 64 depending on the frequency band to which the carrier belongs. Accordingly, the maximum number of SSB beams in the SSB burst set may also be given as follows according to the frequency band of the carrier.

-For frequency range up to 3 GHz, Max number of beams = 4

-For frequency range from 3GHz to 6 GHz, Max number of beams = 8

-For frequency range from 6 GHz to 52.6 GHz, Max number of beams = 64

* When multi-beam transmission is not applied, the number of SSB beams is 1.

When the terminal attempts to initially access the base station, the terminal may align the base station and the beam based on the SSB. For example, after performing SSB detection, the terminal identifies the best SSB. Thereafter, the UE may transmit the RACH preamble to the base station by using the PRACH resource linked/corresponding to the index (ie, the beam) of the best SSB. The SSB can be used to align the beam between the base station and the terminal even after initial access.

Channel measurement and rate-matching

11 illustrates a method of informing an actually transmitted SSB (SSB_tx).

In the SSB burst set, a maximum of L SSBs may be transmitted, and the number/locations at which SSBs are actually transmitted may vary for each base station/cell. The number/locations at which SSBs are actually transmitted is used for rate-matching and measurement, and information on the actually transmitted SSBs is indicated as follows.

-In case of rate-matching: It may be indicated through UE-specific RRC signaling or RMSI. The UE-specific RRC signaling includes a full (eg, length L) bitmap in both the below 6GHz and above 6GHz frequency ranges. On the other hand, RMSI includes a full bitmap at below 6GHz, and includes a compressed bitmap at above 6GHz. Specifically, information on the actually transmitted SSB may be indicated using a group-bit map (8 bits) + an intra-group bit map (8 bits). Here, a resource (eg, RE) indicated through UE-specific RRC signaling or RMSI is reserved for SSB transmission, and PDSCH/PUSCH may be rate-matched in consideration of SSB resources.

-In the case of measurement: In the case of RRC connected (connected) mode, the network (eg, the base station) may indicate the SSB set to be measured within the measurement interval. The SSB set may be indicated for each frequency layer. If there is no indication regarding the SSB set, the default SSB set is used. The default SSB set includes all SSBs in the measurement interval. The SSB set may be indicated using a full (eg, length L) bitmap of RRC signaling. When in RRC idle mode, the default SSB set is used.

Random Access (RA) process

12 illustrates an example of a random access process. In particular, FIG. 12 illustrates a contention-based random access process.

First, the UE (terminal) may transmit the random access preamble as Msg1 in the random access procedure in the UL through the PRACH.

Random access preamble sequences having two different lengths are supported. Long sequence length 839 is applied for subcarrier spacing of 1.25 and 5 kHz, and short sequence length 139 is applied for subcarrier spacing of 15, 30, 60 and 120 kHz.

Multiple preamble formats are defined by one or more RACH OFDM symbols and different cyclic prefixes (and/or guard times). The RACH configuration for the initial bandwidth of the primary cell (Pcell) is included in the system information of the cell and provided to the terminal. The RACH configuration includes information on the subcarrier spacing of the PRACH, available preambles, and preamble format. The RACH configuration includes association information between SSBs and RACH (time-frequency) resources. The UE transmits a random access preamble in the RACH time-frequency resource associated with the detected or selected SSB.

The SSB threshold for RACH resource association can be set by the network, and the RACH preamble is transmitted based on the SSB in which the reference signal received power (RSRP) measured based on the SSB satisfies the threshold. Or, retransmission is performed. For example, the UE may select one of SSB(s) meeting the threshold value, and transmit or retransmit the RACH preamble based on the RACH resource associated with the selected SSB. For example, upon retransmission of the RACH preamble, the UE may reselect one of the SSB(s) and retransmit the RACH preamble based on the RACH resource associated with the reselected SSB. That is, the RACH resource for retransmission of the RACH preamble may be the same and/or different from the RACH resource for transmission of the RACH preamble.

When the BS (base station) receives the random access preamble from the UE, the BS transmits a random access response (RAR) message (Msg2) to the UE. The PDCCH for scheduling the PDSCH carrying RAR is transmitted after being CRC scrambled with a random access (RA) radio network temporary identifier (RNTI) (RA-RNTI). A UE that detects a PDCCH CRC scrambled with RA-RNTI may receive a RAR from a PDSCH scheduled by a DCI carried by the PDCCH. The UE checks whether the preamble transmitted by the UE, that is, random access response information for Msg1, is in the RAR. Whether there is random access information for Msg1 transmitted by the UE may be determined based on whether a random access preamble ID for a preamble transmitted by the UE exists. If there is no response to Msg1, the UE may retransmit the RACH preamble within a certain number of times while performing power ramping. The UE calculates the PRACH transmit power for retransmission of the preamble based on the most recent transmit power, power increment amount, and power ramping counter.

Random access response information includes a preamble sequence transmitted by the terminal, a temporary cell-RNTI (TC-RNTI) allocated by the base station to the terminal attempting random access, and uplink transmit time alignment information. , Uplink transmission power adjustment information and uplink radio resource allocation information may be included. When the UE receives random access response information for itself on the PDSCH, the UE can know timing advance information for UL synchronization, an initial UL grant, and TC-RNTI. The timing advance information is used to control the uplink signal transmission timing. In order to better align the PUSCH/PUCCH transmission by the UE with the subframe timing at the network side, the network (eg, BS) provides timing advance information based on timing information detected from the PRACH preamble received from the UE. Acquire and transmit the corresponding timing advance information to the terminal. The UE may transmit UL transmission as Msg3 in a random access procedure on an uplink shared channel based on random access response information. Msg3 may include an RRC connection request and a UE identifier. In response to Msg3, the network may send Msg4, which may be treated as a contention resolution message on the DL. By receiving Msg4, the UE can enter the RRC connected state.

On the other hand, the contention-free random access procedure may be used in the process of handing over to another cell or BS by the UE, or may be performed when requested by the command of the BS. The basic process of the contention-free random access process is similar to the contention-based random access process. However, unlike a contention-based random access process in which the UE randomly selects a preamble to be used among a plurality of random access preambles, in the case of a contention-free random access process, the preamble to be used by the UE (hereinafter, a dedicated random access preamble) is determined by the BS. It is assigned to the UE. Information on the dedicated random access preamble may be included in an RRC message (eg, a handover command) or may be provided to the UE through a PDCCH order. When the random access procedure is initiated, the UE transmits a dedicated random access preamble to the BS. When the UE receives the random access process from the BS, the random access process is completed.

As mentioned above, the UL grant in the RAR schedules PUSCH transmission to the UE. The PUSCH carrying the initial UL transmission by the UL grant in the RAR is also referred to as Msg3 PUSCH. The contents of the RAR UL grant start at the MSB and end at the LSB, and are given in Table 5.

RAR UL grant field	Number of bits
Frequency hopping flag	One
Msg3 PUSCH frequency resource allocation	12
Msg3 PUSCH time resource allocation	4
Modulation and coding scheme (MCS)	4
Transmit power control (TPC) for Msg3 PUSCH	3
CSI request	One

The TPC command is used to determine the transmit power of the Msg3 PUSCH, and is interpreted according to Table 6, for example.

TPC command	value [dB]
0	-6
One	-4
2	-2
3	0
4	2
5	4
6	6
7	8

In the contention-free random access procedure, the CSI request field in the RAR UL grant indicates whether the UE will include an aperiodic CSI report in the corresponding PUSCH transmission. The subcarrier spacing for Msg3 PUSCH transmission is provided by the RRC parameter. The UE will transmit PRACH and Msg3 PUSCH on the same uplink carrier of the same serving cell. The UL BWP for Msg3 PUSCH transmission is indicated by System Information Block1 (SIB1).

Multiplexing of Short PUCCH and Long PUCCH

13 illustrates a configuration in which Short PUCCH and Long PUCCH are multiplexed with an uplink signal.

PUCCH (eg, PUCCH format 0/2) and PUSCH may be multiplexed in a TDM or FDM scheme. Short PUCCH and long PUCCH from different terminals may be multiplexed in a TDM or FDM scheme. Short PUCCHs from a single terminal in one slot may be multiplexed in a TDM scheme. Short PUCCH and long PUCCH from a single terminal in one slot may be multiplexed in a TDM or FDM scheme.

ACK/NACK transmission

14 illustrates an ACK/NACK transmission process. Referring to FIG. 14, the UE may detect the PDCCH in slot #n. Here, the PDCCH includes downlink scheduling information (eg, DCI formats 1_0, 1_1), and the PDCCH represents a DL assignment-to-PDSCH offset (K0) and a PDSCH-HARQ-ACK reporting offset (K1). For example, DCI formats 1_0 and 1_1 may include the following information.

-Frequency domain resource assignment: indicates the RB set assigned to the PDSCH

-Time domain resource assignment: K0, indicating the starting position (eg, OFDM symbol index) and length (eg number of OFDM symbols) of the PDSCH in the slot

-PDSCH-to-HARQ_feedback timing indicator: indicates K1

Thereafter, after receiving the PDSCH in slot #(n+K0) according to the scheduling information of slot #n, the UE may transmit UCI through PUCCH in slot #(n+K1). Here, the UCI includes a HARQ-ACK response for the PDSCH. When the PDSCH is configured to transmit a maximum of 1 TB, the HARQ-ACK response may be configured with 1-bit. When the PDSCH is configured to transmit up to two TBs, the HARQ-ACK response may consist of 2-bits when spatial bundling is not configured, and may consist of 1-bits when spatial bundling is configured. When the HARQ-ACK transmission time point for a plurality of PDSCHs is designated as slot #(n+K1), the UCI transmitted in slot #(n+K1) includes HARQ-ACK responses for the plurality of PDSCHs.

Bandwidth Part (BWP)

In the NR system, up to 400 MHz can be supported per one carrier. If the UE operating on such a wideband carrier always operates with a radio frequency (RF) module for the entire carrier on, the UE battery consumption may increase. Or, considering several use cases (eg, eMBB, URLLC, mMTC, V2X, etc.) operating within one wideband carrier, different numerology (eg, subcarrier spacing) for each frequency band within the corresponding carrier. Can be supported. Alternatively, each UE may have different capabilities for the maximum bandwidth. In consideration of this, the base station may instruct the UE to operate only in a portion of the bandwidth, not the entire bandwidth of the wideband carrier, and the portion of the bandwidth is referred to as a bandwidth part (BWP). In the frequency domain, the BWP is a subset of contiguous common resource blocks defined for the neurology μi in the bandwidth part i on the carrier, and one neurology (e.g., subcarrier spacing, CP length, slot/mini-slot duration) Period) can be set.

Meanwhile, the base station may set one or more BWPs in one carrier set to the UE. Alternatively, when UEs are concentrated in a specific BWP, some UEs may be moved to another BWP for load balancing. Alternatively, in consideration of frequency domain inter-cell interference cancellation between neighboring cells, some spectrum of the entire bandwidth may be excluded and both BWPs of the cell may be set in the same slot. That is, the base station may set at least one DL/UL BWP to the UE associated with the wideband carrier, and at least one DL/UL BWP among the DL/UL BWP(s) set at a specific time (physical L1 signaling as a layer control signal, MAC control element (CE) as a MAC layer control signal, or RRC signaling) can be activated and switch to another configured DL/UL BWP (L1 signaling, MAC CE, or by RRC signaling) or by setting a timer value so that the UE switches to a predetermined DL/UL BWP when the timer expires. In this case, in order to indicate to switch to another configured DL/UL BWP, DCI format 1_1 or DCI format 0_1 may be used. The activated DL/UL BWP is specifically referred to as the active DL/UL BWP. In a situation such as when the UE is in the process of initial access or before the RRC connection of the UE is set up, the UE may not be able to receive the configuration for the DL/UL BWP. In this situation, the DL/UL BWP assumed by the UE is called an initial active DL/UL BWP.

Meanwhile, the DL BWP is a BWP for transmitting and receiving a downlink signal such as a PDCCH and/or a PDSCH, and the UL BWP is a BWP for transmitting and receiving an uplink signal such as a PUCCH and/or a PUSCH.

In the NR system, a downlink channel and/or a downlink signal can be transmitted and received in an active DL Downlink Bandwidth Part (BWP). In addition, an uplink channel and/or an uplink signal may be transmitted and received within an active UL BWP (Uplink Bandwidth Part).

Downlink channel structure

The base station transmits a related signal to the terminal through a downlink channel to be described later, and the terminal receives a related signal from the base station through a downlink channel to be described later.

(1) Physical downlink shared channel (PDSCH)

The PDSCH carries downlink data (e.g., DL-shared channel transport block, DL-SCH TB), and modulation methods such as Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM), 64 QAM, and 256 QAM are used. Apply. A codeword is generated by encoding TB. The PDSCH can carry up to two codewords. Scrambling and modulation mapping are performed for each codeword, and modulation symbols generated from each codeword are mapped to one or more layers (Layer mapping). Each layer is mapped to a resource together with a demodulation reference signal (DMRS) to generate an OFDM symbol signal, and is transmitted through a corresponding antenna port.

(2) Physical downlink control channel (PDCCH)

The PDCCH carries downlink control information (DCI) and a QPSK modulation method is applied. One PDCCH is composed of 1, 2, 4, 8, 16 Control Channel Elements (CCEs) according to the Aggregation Level (AL). One CCE consists of 6 REGs (Resource Element Group). One REG is defined by one OFDM symbol and one (P)RB.

15 illustrates one REG structure. In FIG. 15, D represents a resource element (RE) to which DCI is mapped, and R represents an RE to which DMRS is mapped. The DMRS is mapped to RE #1, RE #5 and RE #9 in the frequency domain direction within one symbol.

The PDCCH is transmitted through a control resource set (CORESET). CORESET is defined as a REG set with a given pneumonology (eg, SCS, CP length, etc.). A plurality of OCRESETs for one terminal may overlap in the time/frequency domain. CORESET may be set through system information (eg, MIB) or UE-specific higher layer (eg, Radio Resource Control, RRC, layer) signaling. Specifically, the number of RBs constituting CORESET and the number of symbols (maximum 3) may be set by higher layer signaling.

The precoder granularity in the frequency domain for each CORESET is set to one of the following by higher layer signaling:

-sameAsREG-bundle: same as REG bundle size in frequency domain

-allContiguousRBs: same as the number of consecutive RBs in the frequency domain inside CORESET

REGs in CORESET are numbered based on a time-first mapping manner. That is, REGs are numbered sequentially from 0 starting from the first OFDM symbol in the lowest-numbered resource block inside the CORESET.

The mapping type from CCE to REG is set to one of a non-interleaved CCE-REG mapping type or an interleaved CCE-REG mapping type. FIG. 16(a) illustrates a non-interleaved CCE-REG mapping type, and FIG. 16(b) illustrates an interleaved CCE-REG mapping type.

-Non-interleaved CCE-REG mapping type (or localized mapping type): 6 REGs for a given CCE constitute one REG bundle, and all REGs for a given CCE are contiguous. One REG bundle corresponds to one CCE

-Interleaved (interleaved) CCE-REG mapping type (or Distributed mapping type): 2, 3, or 6 REGs for a given CCE constitute one REG bundle, and the REG bundles are interleaved in CORESET. The REG bundle in the CORESET consisting of 1 OFDM symbol or 2 OFDM symbols consists of 2 or 6 REGs, and the REG bundle in the CORESET consisting of 3 OFDM symbols consists of 3 or 6 REGs. REG bundle size is set for each CORESET

17 illustrates a block interleaver. The number of rows (A) of the (block) interleaver for the above interleaving operation is set to one of 2, 3, and 6. When the number of interleaving units for a given CORESET is P, the number of columns of the block interleaver is equal to P/A. A write operation for the block interleaver is performed in a row-first direction as shown in FIG. 17 below, and a read operation is performed in a column-first direction. The interleaving unit cyclic shift (CS) is applied based on an ID that can be set independently for an ID that can be set for DMRS.

The UE acquires DCI transmitted through the PDCCH by performing decoding (aka, blind decoding) on the set of PDCCH candidates. The set of PDCCH candidates decoded by the UE is defined as a PDCCH search space set. The search space set may be a common search space or a UE-specific search space. The UE may acquire DCI by monitoring PDCCH candidates in one or more search space sets set by MIB or higher layer signaling. Each CORESET setting is associated with one or more sets of search spaces, and each set of search spaces is associated with one COREST setting. One set of search spaces is determined based on the following parameters.

-controlResourceSetId: represents the set of control resources related to the search space set

-monitoringSlotPeriodicityAndOffset: indicates PDCCH monitoring period interval (slot unit) and PDCCH monitoring interval offset (slot unit)

-monitoringSymbolsWithinSlot: indicates the PDCCH monitoring pattern in the slot for PDCCH monitoring (eg, indicates the first symbol(s) of the control resource set)

-nrofCandidates: indicates the number of PDCCH candidates per AL={1, 2, 4, 8, 16} (one of 0, 1, 2, 3, 4, 5, 6, 8)

Table 7 exemplifies features of each search space type.

Type	Search Space	RNTI	Use Case
Type0-PDCCH	Common	SI-RNTI on a primary cell	SIB Decoding
Type0A-PDCCH	Common	SI-RNTI on a primary cell	SIB Decoding
Type1-PDCCH	Common	RA-RNTI or TC-RNTI on a primary cell	Msg2, Msg4 decoding in RACH
Type2-PDCCH	Common	P-RNTI on a primary cell	Paging Decoding
Type3-PDCCH	Common	INT-RNTI, SFI-RNTI, TPC-PUSCH-RNTI, TPC-PUCCH-RNTI, TPC-SRS-RNTI, C-RNTI, MCS-C-RNTI, or CS-RNTI(s)
	UE Specific	C-RNTI, or MCS-C-RNTI, or CS-RNTI(s)	User specific PDSCH decoding

Table 8 exemplifies DCI formats transmitted through the PDCCH.

DCI format	Usage
0_0	Scheduling of PUSCH in one cell
0_1	Scheduling of PUSCH in one cell
1_0	Scheduling of PDSCH in one cell
1_1	Scheduling of PDSCH in one cell
2_0	Notifying a group of UEs of the slot format
2_1	Notifying a group of UEs of the PRB(s) and OFDM symbol(s) where UE may assume no transmission is intended for the UE
2_2	Transmission of TPC commands for PUCCH and PUSCH
2_3	Transmission of a group of TPC commands for SRS transmissions by one or more UEs

DCI format 0_0 is used to schedule TB-based (or TB-level) PUSCH, DCI format 0_1 is TB-based (or TB-level) PUSCH or CBG (Code Block Group)-based (or CBG-level) PUSCH Can be used to schedule DCI format 1_0 is used to schedule TB-based (or TB-level) PDSCH, DCI format 1_1 is used to schedule TB-based (or TB-level) PDSCH or CBG-based (or CBG-level) PDSCH I can. DCI format 2_0 is used to deliver dynamic slot format information (eg, dynamic SFI) to the terminal, and DCI format 2_1 is used to deliver downlink pre-Emption information to the terminal. DCI format 2_0 and/or DCI format 2_1 may be delivered to UEs within a corresponding group through a group common PDCCH, which is a PDCCH delivered to UEs defined as one group.

Prior to the detailed description, an example of implementing operations of a terminal and a base station according to an embodiment of the present disclosure will be described with reference to FIGS. 18 to 19.

18 is a diagram for describing an example of an operation implementation of a terminal according to the present disclosure. Referring to FIG. 18, the UE may transmit a message A including a physical random access channel (PRACH) preamble and a physical uplink shared channel (PUSCH) (S1801). And in response to the message A, it is possible to receive a message B including contention resolution information (S1803). In this case, a specific method for the UE of S1801 to S1803 to perform the random access process may be based on the embodiments and features described later.

Meanwhile, the terminal of FIG. 18 may be any one of various wireless devices disclosed in FIGS. 27 to 30. For example, the terminal of FIG. 18 may be the first wireless device 100 of FIG. 27 or the wireless devices 100 and 200 of FIG. 28. In other words, the operation process of FIG. 18 may be performed and executed by any one of various wireless devices disclosed in FIGS. 27 to 30.

19 is a diagram for describing an example of an operation implementation of a base station according to the present disclosure. Referring to FIG. 19, the base station receives a message A including a PRACH (Physical Random Access Channel) preamble and a PUSCH (Physical Uplink Shared Channel) (S1901), and in response to the message A, contention resolution Message B including information may be transmitted (S1903). In this case, a specific method for the base station of S1901 to S1903 to perform the random access process may be based on the embodiments and features described later.

Meanwhile, the base station of FIG. 19 may be any one of various wireless devices disclosed in FIGS. 27 to 30. For example, the base station of FIG. 19 may be the second wireless device 200 of FIG. 27 or the wireless devices 100 and 200 of FIG. 28. In other words, the operation process of FIG. 19 may be performed and executed by any one of various wireless devices disclosed in FIGS. 27 to 30.

In the LTE and/or NR system, the UE may perform UL transmission through a random access procedure (RACH Procedure) without being scheduled for direct uplink (UL) transmission from a given base station or cell. From the terminal point of view, the random access process in the LTE and/or system includes: 1) transmission of a random access preamble, 2) reception of a message (Msg) 2 corresponding to a random access response (RAR) , 3) Transmission of Msg 3 including Physical Uplink Shared Channel (PUSCH), 4) 4-step of reception of Msg 4 including information on contention resolution ) Procedure.

Here, Msg 2 is a message in which the base station receiving a preamble allocates UL resources to be used when the terminal transmitting the preamble transmits Msg 3. Through Msg 3, the terminal provides a connection request along with its own identification information, such as an International Mobile Subscriber Identity (IMSI) or a Temporary Mobile Subscriber Identity (TMSI). Information can be transmitted. The base station receiving Msg 3 transmits identification information of the corresponding terminal and information necessary for random access through Msg 4, thereby preventing collisions that may occur between different terminals during the random access process, and performing a random access procedure for the corresponding terminal. Can be completed.

Unlike the conventional RACH procedure in LTE and NR Rel-15 that was configured as 4-step as described above, in the newly introduced NR Rel-16, the processing delay by 4-step is simplified and a small cell ( Small cell) or unlicensed bandwidth (unlicensed bandwidth) so that the RACH procedure can be utilized, a 2-step (2-step) RACH procedure research is in progress. In the 2-step RACH, the step of transmitting Message 3 (Msg 3) including a Physical Uplink Shared Channel (PUSCH) in the existing 4-step RACH and a contention resolution message. The step of transmitting Msg 4 has been omitted. Instead, in the first step of the random access procedure, the UE transmits a message corresponding to Msg 3 together with a preamble to the base station as Msg A, and in response to Msg A, the base station sends a message corresponding to Msg 4 together with RAR as Msg B. Send to the terminal. The terminal receiving Msg B completes the random access procedure by decoding Msg B and then performs data transmission/reception.

20 is a diagram showing a basic process of a 2-step RACH. Referring to FIG. 20, the UE receives RACH transmission information included in system information broadcasted from the base station, based on the RACH preamble (or PRACH preamble) and PUSCH in order to perform a random access procedure for the base station. Transmits Msg A including a (S2001). In this case, the RACH preamble and the PUSCH may be transmitted at regular intervals or successively transmitted in the time domain, and the corresponding PUSCH includes information about an identifier (ID) of the terminal. The base station detects the preamble and can predict and receive a PUSCH having a corresponding gap or a continuous PUSCH from the RACH preamble. The base station receives an access request and/or response from an upper layer based on the ID information of the terminal transmitted through the PUSCH, and then sends Msg B including information such as RAR and contention resolution to the terminal as a response to Msg A. It is transmitted (S2003). Thereafter, depending on whether the terminal receives Msg B, the terminal can complete access to the base station and transmit and receive data with the base station in the same or similar manner as after the operation of receiving Msg 4 in the existing 4-step RACH procedure ( S2005).

In the case of the 4-step RACH procedure in NR, the start time and period at which the terminal transmitting Msg 1 expects to receive Msg 2 is set as the RAR monitoring window, and the start time of the monitoring window is Type1- It is the first symbol of the fastest core set (COREST) that can detect the PDCCH Common Search Space (CSS) set. At this time, the corresponding start point corresponds to at least one symbol after the last symbol in which the Rach Occasion (RO) of Msg 1 is transmitted on the time axis. The setting of the monitoring window is expressed in units of slots, and one of {sl1, sl2, sl4, sl8, sl10, sl20, sl40, sl80} is transmitted to the terminal through system information. The terminal attempts blind decoding for DCI format 1_0 based on the Random Access-Radio Network Temporary Identifier (RA-RNTI) transmitted by itself during the set monitoring window period, and cannot receive Msg 2 during the period. In this case, the preamble is retransmitted after a predetermined time interval from the last symbol of the set window. Here, the predetermined time interval for retransmitting the preamble is

msec and

Is determined according to the processing capability of the terminal for receiving the PDSCH.

When the terminal correctly receives Msg 2, the terminal transmits Msg 3 based on the UL grant information included in Msg 2, and at this time, a contention resolution timer from the time of the first symbol used for transmission of Msg 3 (contention resolution timer; CR timer) is set. The value of the CR timer is expressed in subframe units, and one of {sf8, sf16, sf24, sf32, sf40, sf48, sf56, sf64} is transmitted to the terminal through system information. The terminal expects to receive Msg 4 during the set timer period, and performs additional operations for random access according to information included in Msg 4 and whether the timer expires.

21 is a diagram illustrating messages transmitted and received in a 4-step RACH procedure along a time axis. According to FIG. 21, the above-described contents regarding transmission/reception of Msg 1 to 4 in the 4-step RACH procedure, the setting of the RAR monitoring window, and the setting of the CR timer are diagrammed over time. First, the UE transmits Msg 1 including a preamble to the base station, and receives Msg 2 from the base station through a RAR monitoring window set after at least one symbol from the last symbol in which the preamble is transmitted. Thereafter, the terminal transmits Msg 3 to the base station based on the information included in Msg 2, and receives Msg 4 from the base station during the period of the CR timer set from the time point of the first symbol used for transmission of Msg 3. Thereafter, the terminal completes the random access procedure and transmits and receives data with the base station.

On the other hand, in the 2-step RACH procedure, the terminal does not receive two messages of Msg 2 and 4 as in the 4-step RACH procedure, but receives one message of Msg B, so that the terminal performs a series of procedures related to contention resolution. In order to do this, it may be necessary to set up a window and/or timer using these features. In addition, in order to successfully perform the 2-step RACH procedure, the base station must receive all of the RACH preamble and PUSCH included in Msg A. If neither of these is received, the retransmission of Msg A or the 4-step RACH procedure Fall-back, etc. are required, and in this process, Msg 2 of RAR can be used.

In the following disclosure, in the case where the UE transmits Msg A in the 2-step RACH procedure and is in an environment in which Msg 2 can be detected and decoded before receiving Msg B, transmission and reception of Msg B is performed using Msg 2 Describes a method for setting a window and/or a timer for, and follow-up operations such as Msg B reception, Msg A retransmission, and/or fall-back to 4-step RACH procedure according to the information included in Msg 2 Be able to write about

RAR monitoring window and CR timer

In the case where the UE transmits a preamble from a specific RO to perform a 4-step RACH procedure, it was confirmed that the RAR monitoring window can be set as shown in FIG. 21 described above. Although the setting of the RAR monitoring window is for performing a 4-step RACH procedure, the terminal may use a similar RAR monitoring window setting in the 2-step RACH procedure.

For example, if the UE transmits a preamble in the same RO as the specific RO to perform a 2-step RACH procedure, the UE sets the value of the RAR monitoring window configured for the 4-step RACH procedure to the 2-step RACH procedure. Can be used similarly for That is, the terminal performing the 2-step RACH procedure can use the same start time and duration value of the RAR monitoring window as in the 4-step RACH procedure, and the contention resolution timer (CR timer) is used for PUSCH transmission based on Msg A. It can operate after the last symbol to be used. Specifically, the RAR monitoring window starts from the first symbol of CORESET available at a time point after at least one symbol from the last symbol of the RO, PUSCH is transmitted within the window, and after the last symbol in which PUSCH is transmitted. The CR timer can be activated. That is, although the UE transmits Msg A, it can expect not only to receive Msg B by using Msg B-RNTI, but also to receive RAR by using RA-RNTI that transmitted preamble within the corresponding RAR monitoring window.

At this time, the UE intending to perform the 2-step RACH procedure transmits the PUSCH when the RAR monitoring window is longer than a certain length or longer than a minimum time duration in order to perform an access procedure faster than the 4-step RACH procedure. can do. That is, the size of the RAR monitoring window is at least, 1) a larger time interval value among the actual RAR transmission time including the PDCCH and PDSCH for Msg 2 or the actual transmission time of Msg B including the PDCCH and PDSCH for Msg B , 2) PUSCH transmission time and 3) when the time gap between each signal transmission is greater than the combined time, the UE may attempt a 2-step RACH procedure. Here, the transmission time of Msg 2 and Msg B may be determined as a maximum or minimum time interval that may be required for each transmission.

The RAR transmission time required to determine the size of the RAR monitoring window may be determined by the maximum PDCCH symbol interval and the maximum PDSCH symbol interval in connection with the delivery of the RAR message. In addition, the time gap required to determine the size of the RAR monitoring window is a value determined in consideration of inter-symbol interference (ISI) and cell coverage occurring in preamble and PUSCH transmission. In this case, the time gap may additionally include a processing delay required for RAR reception and preparation for transmission of the PUSCH.

The UE may select and perform a 2-step RACH procedure or a 4-step RACH procedure according to the size of the RAR monitoring window, and the size of the RAR monitoring window may be a criterion for performing the RACH procedure. For example, when the size of the RAR monitoring window is larger than the above-described minimum value, the UE may select and perform a 2-step RACH procedure. On the other hand, if the size of the RAR monitoring window does not meet the minimum length as described above, there is no difference from the 4-step RACH procedure in terms of latency. In this case, the terminal transmits only the preamble and receives the RAR, but the received RAR Based on Msg 3, a 4-step RACH procedure can be performed.

22 is a diagram illustrating a RAR monitoring window that serves as a reference for performing a RACH procedure. In FIG. 22, it can be seen that the RAR monitoring window set in the terminal at a time point after at least one symbol interval in the last symbol in which the preamble was transmitted is configured to include a transmission time, a time gap, and a PUSCH transmission time of RAR or Msg B. have. That is, in this case, since the size of the RAR monitoring window configured in the terminal satisfies the minimum length requirement, the terminal selects and performs a 2-step RACH procedure. Unlike FIG. 22, if the size of the RAR monitoring window is determined so as not to include any of the transmission time, time gap, and PUSCH transmission time of RAR or Msg B, the terminal will select and perform a 4-step RACH procedure. .

In the case of using the CR timer value in the existing 4-step RACH procedure as it is without setting additional CR timer in the 2-step RACH procedure, the application point of the CR timer is the start symbol or the last ) Can be a symbol. That is, the start time of the CR timer may be 1) the first symbol of PUSCH transmission, or 2) immediately after the last symbol of PUSCH transmission or after the processing delay for the reception of Msg B from the last symbol of PUSCH transmission. I can. When the CR timer operates, the UE performs blind decoding using an RNTI related to the PDCCH of Msg B in order to receive Msg B. The base station must transmit Msg B before the end of the CR timer in consideration of the configured CR timer value and the PUSCH reception time.

On the other hand, the UE is the time and frequency resources used for preamble transmission, regardless of whether the UE transmits Msg A or sets the 2-step/4-step RACH procedure of the UE, unless it meets an exception condition. Time/Frequency resource) can always be expected to receive RAR in the RAR monitoring window by using the calculated RA-RNTI. Eventually, for the RAR monitoring window configured in the terminal, if the terminal performs a 2-step RACH procedure, the terminal can expect to receive both Msg 2 and Msg B of the RAR. At this time, in the case where the UE can receive both Msg 2 and Msg B in the 2-step RACH procedure, the base station includes information related to the reception of Msg B in Msg 2 so that the UE can smoothly perform the RACH procedure. can do.

Hereinafter, when the terminal can expect the reception of Msg 2 and Msg B as described above, the terminal 1) receives information related to retransmission for Msg A through Msg 2 in relation to the subsequent smooth RACH procedure, or 2) 4 Describe how to receive information indicating Fall-Back to -step RACH Procedure.

Msg A retransmission setting using Msg 2 MAC sub-header

As one of the methods for allowing the UE to smoothly perform the RACH procedure, a method of setting whether and the number of retransmissions of Msg A using RAR may be considered. This method uses the backoff indicator (BI) information of the sub-header in the MAC PDU (Medium Access Control Protocol Data Block) for RAR, which means that all UEs that have transmitted the preamble through the same RO have their Random Access Preamble It is based on the fact that the information of the MAC sub-header is checked regardless of the identification of the identifier (RAPID). Particularly, a retry command for a 2-step RACH procedure may be indicated by indicating whether and how many times Msg A is retransmitted to the UE by using a reserved bit of a field in the MAC sub-header.

In the case of the 2-step RACH procedure, it is intended to access the network faster by processing the entire processing time of the existing 4-step operation in 2-step. When a problem occurs during the connection process and a reconnection attempt is made It is necessary to make the decision of the Msg A retransmission faster. In particular, with respect to the RAR, the UE performing the 2-step RACH procedure may perform retransmission for Msg A if it does not receive the RAR including information for detection of Msg B to be received.

In this case, a method of dynamically setting the number of Msg A retransmissions that the UE intends to perform for the UE performing the 2-step RACH procedure through the reserved bit of the MAC sub-header may be considered. That is, the base station may commonly set the maximum number of retransmissions applied in the 2-step RACH procedure using system information, but based on the above scheme, the maximum number of retransmissions is determined in consideration of the situation of the terminal or base station It can be newly set or changed. In other words, it is possible to place restrictions related to the number of retransmissions of Msg A with respect to the terminals that have transmitted the preamble at the time point of a specific RO.

For example, if there are many terminals that want to perform a 2-step or 4-step RACH procedure at a point in time of a specific RO, the collision probability will be relatively high. In this case, the terminal performing the 2-step RACH procedure is Msg A Even if retransmission is continuously performed, inefficiency may occur in terms of power management. Therefore, in addition to setting the common maximum number of retransmissions as system information, the base station may variably impose a limit on the number of Msg A retransmissions while system information is transmitted.

When the reserved bit of the MAC sub-header through which BI information is transmitted is used, the UE can obtain information on the number of Msg A retransmissions regardless of RAPID, so the UE cannot receive the RAR or the base station does not detect the preamble. Even if it is not possible, a specific number of Msg A retransmissions can be set to the terminal. Here, the failure of the UE to receive the RAR may mean that the UE fails to properly decode the RAR and thus does not acquire desired information. A specific method of indicating the number of retransmissions may vary as follows depending on whether the reserved bits are singular or plural.

1) Indication using a single reserved bit

This is a method of indicating the number of retransmissions by using one single bit among all reserved bits. For a terminal that has not received Msg 2, if the single bit has a value of 1, the terminal transmits Msg A once more in the next retransmission, and if the single bit has a value of 0, the terminal does not retransmit Msg A. , Msg 1 is transmitted. Here, the single bit is a retransmission indicator, and a bit having a value of 0 indicates the meaning of'off', and a bit having a value of 1 indicates the meaning of'on'. When the single bit is 1, the retransmission time of Msg A may be indicated through BI information.

FIG. 23(a) is a diagram related to an embodiment of indicating Msg A retransmission in a 2-step RACH procedure using a single bit. In FIG. 23(a), it can be seen that one bit denoted as'I' among the bits of Oct 1 constituting the MAC sub-header is a single bit used to indicate the number of retransmissions. For a terminal that has not received Msg 2, if a single bit marked I has a value of 1, the terminal can transmit Msg A once more in the next retransmission, and if a single bit marked with I has a value of 0, the terminal will It will transmit 1.

2) Indication using a plurality of reserved bits

This is a method of indicating the number of retransmissions by using a plurality of bits among all reserved bits. For example, if two bits are used, each bit may be represented by four combinations of 00, 01, 10, and 11, and each of the expressed combinations may be determined to correspond to the number of retransmissions of Msg A. That is, for a terminal that has not received Msg 2, in the case of 00, it indicates not to retransmit Msg A, 01 to retransmit 1 Msg A, 10 to retransmit Msg A 2 times, and 11 to retransmit Msg A 3 times. It may be dictating. Here, the used bits are retransmission indicators, and a bit having a value of 00 indicates the meaning of'off', and a bit having a value of 01 to 11 indicates the meaning of'on'. have.

In this case, the number of bits used to indicate the number of retransmissions is not limited to two, and the number of bits used may increase depending on the number of retransmissions. In the case of using a plurality of bits, unlike the case of using a single bit, a number of retransmissions can be set, so that the number of retransmissions of the base station can be flexibly set.

Meanwhile, the terminal that has obtained the retransmission number information of Msg A through the bits ignores the bits for indicating the number of retransmissions newly obtainable through the corresponding next RAR at the time of reception of the next RAR, and deducts -1 from the initially indicated retransmission number. Retransmission of Msg A can be performed. Or, conversely, when bits for indicating the number of retransmissions are newly acquired through the corresponding next RAR, the previously acquired bits may be initialized immediately after acquisition.

FIG. 23(b) is a diagram related to an embodiment of indicating Msg A retransmission in a 2-step RACH procedure using a plurality of bits. In FIG. 23(b), it can be seen that among the bits of Oct 1 constituting the MAC sub-header, two bits marked with'I' are bits used to indicate the number of retransmissions. For a terminal that has not received Msg 2, if the bits marked with I have a value of 00, the terminal transmits Msg 1, and if the bits marked with I have a value of 01, the terminal sends Msg A once more through the next retransmission. If the bits indicated by I can be transmitted, and the bits indicated by I have a value of 10, the terminal can further transmit Msg A through the next and one retransmission thereafter. If the bits indicated by I have a value of 11, the terminal will After that, Msg A can be further transmitted through retransmission up to two times.

In this case, the above-described method of indicating the retransmission configuration of Msg A using the MAC sub-header can be applied equally to the MAC sub-header of Msg B. That is, in the step of transmitting Msg B, the base station may indicate to the UE whether or not to retransmit Msg A and the number of times, using reserved bits of the sub-header present in the MAC PDU of Msg B.

In this case, the base station can commonly set the maximum number of retransmissions applied in the 2-step RACH procedure using system information, but in consideration of the need for variable Msg A retransmission in the situation where the 2-step RACH procedure is in progress, Msg You can set or change whether A is retransmitted or not. In addition, the UE can check the information of the sub-header in the MAC PDU of Msg B regardless of whether it can decode Msg B, so if Msg B is not decoded correctly, the retransmission information of Msg A included in the sub-header is It can be used to immediately perform retransmission of Msg A.

Similarly, a single bit or a plurality of bits among reserved bits for a sub-header in the MAC PDU of Msg B may be used to indicate the retransmission configuration of Msg A, and specific retransmission configuration information of Msg A according to the value of each bit is described above. It can be configured in the same way as one content.

Fall-Back Mechanism using Msg 2 MAC RAR

As one of the methods for allowing the terminal to smoothly perform the RACH procedure, a method of setting information related to the Fall-Back Mechanism using RAR may be considered. In particular, the base station may 1) transmit information related to the RNTI for PDCCH decoding of Msg B to the terminal through Msg 2, or 2) transmit information on whether decoding success or failure of the PUSCH corresponding to the preamble to the terminal.

In transmitting information about RNTI related to Msg B using Msg 2, the base station transmits RAPID through MAC sub-header as before, and Msg B, such as TC-RNTI for Msg B to be transmitted later, in MAC RAR. It is possible to transmit information on the RNTI required for detection of. The UE ignores the UL grant information in the MAC RAR, but acquires information on the TC-RNTI in the MAC RAR and detects Msg B transmitted later based on the corresponding TC-RNTI.

In transmitting information on whether decoding success or failure of the PUSCH corresponding to the preamble by using Msg 2, the base station receives the preamble using some reserved bits or contents of the RAR transmitted by itself, but does not receive the PUSCH. Etc.

When information is transmitted through the MAC sub-header, UEs based on the same RO can obtain information regardless of their RAPID. When information is transmitted through MAC RAR, the UE checks the RAPID and then obtains RAR information. Because of this, the starting point of the procedure is different from the case in which information is transmitted through the MAC sub-header, and the method in which the terminal and the base station utilize the information is also different. In addition, in the 2-step RACH procedure, since the preamble and the PUSCH can be continuously transmitted through Msg A, the base station needs to transmit result information on the success or failure of PUSCH reception to the terminal. The operation of the terminal and the base station is different.

The result information on the success or failure of PUSCH reception may be indicated to the terminal using the reserved bit of MAR RAR as described above. One single bit is a back-off indicator, and on/off mapping is possible according to its value, and may indicate success or failure of PUSCH reception according to whether the value is 1 or 0. That is, if a single bit has a value of 1 and means on, this indicates that the base station has successfully received the preamble and PUSCH. In this case, the UE ignores the UL grant information included in the MAC RAR, but can transmit data such as PUSCH after the access procedure by using Timing Advance (TA) information included in the MAC RAR. In addition, TC-RNTI information included in the MAC RAR may also be received and used to detect Msg B transmitted later.

On the other hand, if a single bit has a value of 0 and means off, it indicates that the base station has received the preamble but has failed to receive the PUSCH. When the UE confirms that a single bit is off, it is possible to transmit Msg 3 on a 4-step RACH procedure by using UL grant information included in the MAC RAR. That is, when the back-off indicator is indicated as off, this means that PUSCH reception has failed and that a fall-back from a 2-step RACH procedure to a 4-step RACH procedure is indicated. At this time, Timing Advance (TA) information included in the MAC RAR may be used for transmission of Msg 3, and the TC-RNTI information included in the MAC RAR may be used for detection of Msg 4 transmitted later.

FIG. 24 is a diagram related to an embodiment of transmitting result information on whether decoding success or failure of a PUSCH in a 2-step RACH procedure using a single bit. Referring to FIG. 24, it can be seen that one bit denoted as'I' among the bits of Oct 1 constituting the MAC RAR is a back-off indicator and is used for result information on whether decoding success or failure of the PUSCH. When the back-off indicator has a value of 1, it means that the base station has successfully received the preamble and the PUSCH, and when the 2-step RACH procedure is maintained and the terminal successfully receives Msg B, the initial access process is completed. On the other hand, if the back-off indicator has a value of 0, it means that the base station has received the preamble but has failed to receive the PUSCH, and the fall-back is performed by a 4-step RACH procedure, so that the base station and the terminal use Msg 3 and Msg 4 is transmitted and received.

Action when CR timer ends earlier than RAR window

In the 2-step RACH procedure, as described above, the base station and the terminal can expect to transmit and receive both Msg 2 and Msg B, and thus the terminal monitors both Msg 2 and Msg B. Since the CR timer for the reception of Msg B and the RAR monitoring window for the reception of Msg 2 are individually set, the end of the CR timer may be earlier than the end of the RAR monitoring window. At this time, for the terminal monitoring Msg B during the CR timer period, in some cases, 1) the CR timer terminates after completing the reception of Msg B before the terminal receives Msg 2, or 2) Msg B The CR timer is terminated without receiving a message, and there may be a situation where Msg 2 is monitored in the remaining RAR monitoring window section.

If the terminal completes the reception of Msg B before receiving Msg 2, the terminal may terminate the 2-step RACH procedure by completing the subsequent access procedure regardless of the reception of Msg 2. Here, the PDCCH related to Msg B received by the UE is scrambled based on a UE-specific RNTI or scrambled based on a common RNTI such as RA-RNTI. May be.

When the PDCCH related to Msg B is scrambled using a UE-specific RNTI, a new RNTI based on a scrambling sequence used for transmission of a PUSCH or DMRS is defined and may be used for the UE. Alternatively, for the PDCCH related to Msg B, a new RNTI based on RA-RNTI determined according to preamble transmission may be generated and used. If the RA-RNTI generated in the same way as before is used for the case of using the UE-specific RNTI, the UE performing the 2-step RACH procedure and the UE performing the 4-step RACH procedure are based on the same RO. This is because the RA-RNTI generated for each terminal in a situation in which the preamble is transmitted is the same, which may lead to an error in the reception operation of the PDCCH.

When the PDCCH related to Msg B is scrambled using a common RNTI, the UE uses a UL Common Control Channel (CCCH) Service Data Unit (SDU) to transmit to the base station, such as UE-Identifier (UE-ID). You must be able to convey specific information about yourself. In addition, after the contention resolution procedure is performed based on the transmitted UE-ID.

If the CR timer ends without the UE receiving Msg B and some sections of the RAR monitoring window remain, the UE takes different actions depending on whether to attempt to receive Msg 2 in some sections of the remaining RAR monitoring window. I can.

If the terminal expects to receive Msg 2 in some section of the remaining RAR monitoring window, the terminal continues to attempt to detect Msg 2 in the remaining section. At this time, if the UE correctly receives Msg 2, a 4-step RACH procedure for transmitting Msg 3 is naturally performed using the information of Msg 2. On the other hand, if the terminal does not receive Msg 2, the terminal performs retransmission of Msg A or Msg 1 based on BI information. In this case, the retransmission of Msg A or Msg 1 may be performed based on the methods described above in the present disclosure.

On the other hand, the terminal may not expect to receive Msg 2 in some sections of the remaining RAR monitoring window, and may perform retransmission of Msg A or Msg 1 immediately after the CR timer ends. That is, in this case, the terminal no longer performs the reception of Msg 2 in the remaining section of the RAR monitoring window with the end of the CR timer, and retransmits Msg A or Msg 1 based on BI information from the time when the CR timer ends. Will perform. Similarly, at this time, the retransmission of Msg A or Msg 1 may be performed based on the methods described above in the present disclosure.

25 is a diagram illustrating an operation flow of a terminal and a base station for performing a 2-step RACH procedure based on embodiments of the present disclosure. The UE and the base station transmit and receive RACH configuration information for performing the RACH procedure, and the information may also include selection information related to a 2-step (or 4-step) RACH procedure (S2501).

Thereafter, the UE transmits Msg A for performing a 2-step RACH procedure to the base station based on the RACH configuration received from the base station. The UE transmits a preamble by selecting a random index from a preamble set for a 2-step RACH procedure, and transmits a PUSCH through a PUSCH resource related to the transmitted preamble. In this case, the PUSCH may include terminal identification information such as the terminal ID. The base station detects the preamble transmitted by the terminal, predicts the transmission time of the PUSCH after a specific offset from the time when the preamble is detected, and performs decoding on the PUSCH. The base station may check the identification information of the terminal included in the PUSCH and then use it to determine the contention resolution for the corresponding terminal (S2503).

The UE that has transmitted Msg A performs blind decoding by using the associated RNTI to receive Msg B afterwards, and it is also possible to perform decoding on the RAR. The terminal may determine whether the base station succeeds or fails to receive the preamble or PUSCH through the information included in the RAR. Here, the information included in the RAR may be configured by the methods described above in the present disclosure. Thereafter, the UE determines and performs retransmission for Msg A or Msg 1 or Fall-Back to a 4-step RACH procedure. If the CR timer for Msg B ends earlier than the monitoring window for RAR and does not receive Msg B within the CR timer interval, the terminal receives the RAR within the remaining RAR monitoring window interval according to the methods described above in this disclosure. Alternatively, retransmission for Msg A or Msg 1 may be performed.

Meanwhile, the base station may prepare and transmit the information of Msg B according to whether the reception of Msg A is successful, or may include related information in the RAR and transmit the information to the terminal when the preamble or PUSCH reception fails. Similarly, the information included in the RAR here may be configured by the methods described above in the present disclosure (S2505).

Even if Msg A is successfully transmitted, or even if the first transmission fails, the terminal that has transmitted Msg A through a subsequent retransmission process receives Msg B and proceeds with contention resolution. When contention resolution is completed, the random access procedure is completed, so that the terminal can transmit and receive data with the base station. In addition, the base station also transmits Msg B or Msg 4 as a response to the transmission of Msg A and/or retransmission of the terminal or Msg 3 to the terminal. After confirming that the terminal has received Msg B, the base station can perform data transmission/reception with the terminal (S2507).

Although not limited thereto, various descriptions, functions, procedures, proposals, methods, and/or operational flow charts of the present invention disclosed in this document may be applied to various fields requiring wireless communication/connection (eg, 5G) between devices. have.

Hereinafter, it will be illustrated in more detail with reference to the drawings. In the following drawings/description, the same reference numerals may exemplify the same or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise indicated.

26 illustrates a communication system 1 applied to the present invention.

Referring to Fig. 26, a communication system 1 applied to the present invention includes a wireless device, a base station, and a network. Here, the wireless device refers to a device that performs communication using a wireless access technology (eg, 5G NR (New RAT), LTE (Long Term Evolution)), and may be referred to as a communication/wireless/5G device. Although not limited thereto, wireless devices include robots 100a, vehicles 100b-1 and 100b-2, eXtended Reality (XR) devices 100c, hand-held devices 100d, and home appliances 100e. ), an Internet of Thing (IoT) device 100f, and an AI device/server 400. For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, and a vehicle capable of performing inter-vehicle communication. Here, the vehicle may include an Unmanned Aerial Vehicle (UAV) (eg, a drone). XR devices include AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) devices, including HMD (Head-Mounted Device), HUD (Head-Up Display), TV, smartphone, It can be implemented in the form of a computer, wearable device, home appliance, digital signage, vehicle, robot, and the like. Portable devices may include smart phones, smart pads, wearable devices (eg, smart watches, smart glasses), computers (eg, notebook computers, etc.). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors, smart meters, and the like. For example, the base station and the network may be implemented as a wireless device, and the specific wireless device 200a may operate as a base station/network node to another wireless device.

The wireless devices 100a to 100f may be connected to the network 300 through the base station 200. AI (Artificial Intelligence) technology may be applied to the wireless devices 100a to 100f, and the wireless devices 100a to 100f may be connected to the AI server 400 through the network 300. The network 300 may be configured using a 3G network, a 4G (eg, LTE) network, or a 5G (eg, NR) network. The wireless devices 100a to 100f may communicate with each other through the base station 200 / network 300, but may perform direct communication (e.g. sidelink communication) without going through the base station / network. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g. V2V (Vehicle to Vehicle)/V2X (Vehicle to Everything) communication). In addition, the IoT device (eg, sensor) may directly communicate with other IoT devices (eg, sensors) or other wireless devices 100a to 100f.

Wireless communication/ connections 150a, 150b, and 150c may be established between the wireless devices 100a to 100f / base station 200 and the base station 200 / base station 200. Here, the wireless communication/connection includes various wireless access such as uplink/downlink communication 150a, sidelink communication 150b (or D2D communication), base station communication 150c (eg relay, Integrated Access Backhaul). This can be achieved through technology (eg 5G NR) Through wireless communication/ connections 150a, 150b, 150c, the wireless device and the base station/wireless device, and the base station and the base station can transmit/receive radio signals to each other. For example, the wireless communication/ connection 150a, 150b, 150c can transmit/receive signals through various physical channels. To this end, based on various proposals of the present invention, for transmission/reception of wireless signals At least some of a process of setting various configuration information, various signal processing processes (eg, channel encoding/decoding, modulation/demodulation, resource mapping/demapping, etc.), resource allocation process, and the like may be performed.

27 illustrates a wireless device applicable to the present invention.

Referring to FIG. 27, the first wireless device 100 and the second wireless device 200 may transmit and receive wireless signals through various wireless access technologies (eg, LTE and NR). Here, {the first wireless device 100, the second wireless device 200} is the {wireless device 100x, the base station 200} and/or {wireless device 100x, wireless device 100x) of FIG. 26 } Can be matched.

The first wireless device 100 includes one or more processors 102 and one or more memories 104, and may further include one or more transceivers 106 and/or one or more antennas 108. The processor 102 controls the memory 104 and/or the transceiver 106 and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed herein. For example, the processor 102 may process information in the memory 104 to generate first information/signal, and then transmit a radio signal including the first information/signal through the transceiver 106. In addition, the processor 102 may store information obtained from signal processing of the second information/signal in the memory 104 after receiving a radio signal including the second information/signal through the transceiver 106. The memory 104 may be connected to the processor 102 and may store various information related to the operation of the processor 102. For example, the memory 104 may perform some or all of the processes controlled by the processor 102, or instructions for performing the descriptions, functions, procedures, suggestions, methods, and/or operational flow charts disclosed in this document. It can store software code including Here, the processor 102 and the memory 104 may be part of a communication modem/circuit/chip designed to implement wireless communication technology (eg, LTE, NR). The transceiver 106 may be coupled with the processor 102 and may transmit and/or receive radio signals through one or more antennas 108. The transceiver 106 may include a transmitter and/or a receiver. The transceiver 106 may be mixed with an RF (Radio Frequency) unit. In the present invention, the wireless device may mean a communication modem/circuit/chip.

Specifically, commands and/or operations that are controlled by the processor 102 of the first wireless device 100 and stored in the memory 104 according to an embodiment of the present invention will be described.

The following operations are described based on the control operation of the processor 102 from the perspective of the processor 102, but may be stored in the memory 104 in software code or the like for performing these operations.

The processor 102 may control the transceiver 106 to transmit a message A including a PRACH (Physical Random Access Channel) preamble and a PUSCH (Physical Uplink Shared Channel). And the processor 102 can control the transceiver 106 to receive the message B containing contention resolution information. In this case, a specific method of controlling the transceiver 106 so that the processor 102 transmits the message A and the transceiver 106 to receive the message B may be based on the above-described embodiments.

Specifically, commands and/or operations controlled by the processor 202 of the second wireless device 200 according to an embodiment of the present invention and stored in the memory 204 will be described.

The following operations are described based on the control operation of the processor 202 from the perspective of the processor 202, but may be stored in the memory 204, such as software code for performing these operations.

The processor 202 may control the transceiver 206 to receive a message A including a PRACH (Physical Random Access Channel) preamble and a PUSCH (Physical Uplink Shared Channel). And the processor 202 can control the transceiver 206 to send a message B containing contention resolution information. In this case, a specific method of controlling the transceiver 206 so that the processor 202 receives the message A and the transceiver 206 to transmit the message B may be based on the above-described embodiments.

Hereinafter, the hardware elements of the wireless devices 100 and 200 will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors 102, 202. For example, one or more processors 102, 202 may implement one or more layers (eg, functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors 102, 202 may be configured to generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Units (SDUs) according to the description, functions, procedures, proposals, methods, and/or operational flow charts disclosed in this document. Can be generated. One or more processors 102, 202 may generate messages, control information, data, or information according to the description, function, procedure, suggestion, method, and/or operational flow chart disclosed herein. At least one processor (102, 202) generates a signal (e.g., a baseband signal) including PDU, SDU, message, control information, data or information according to the functions, procedures, proposals and/or methods disclosed herein. , It may be provided to one or more transceivers (106, 206). One or more processors 102, 202 may receive signals (e.g., baseband signals) from one or more transceivers 106, 206, and the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed herein PDUs, SDUs, messages, control information, data, or information may be obtained according to the parameters.

One or more of the processors 102 and 202 may be referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more of the processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) May be included in one or more processors 102 and 202. The description, functions, procedures, suggestions, methods, and/or operational flow charts disclosed in this document may be implemented using firmware or software, and firmware or software may be implemented to include modules, procedures, functions, and the like. The description, functions, procedures, proposals, methods and/or operational flow charts disclosed in this document are included in one or more processors 102, 202, or stored in one or more memories 104, 204, and are It may be driven by the above processors 102 and 202. The descriptions, functions, procedures, proposals, methods and/or operational flowcharts disclosed in this document may be implemented using firmware or software in the form of codes, instructions and/or a set of instructions.

One or more memories 104 and 204 may be connected to one or more processors 102 and 202 and may store various types of data, signals, messages, information, programs, codes, instructions and/or instructions. One or more of the memories 104 and 204 may be composed of ROM, RAM, EPROM, flash memory, hard drive, registers, cache memory, computer readable storage media, and/or a combination of the elements. One or more memories 104 and 204 may be located inside and/or outside of one or more processors 102 and 202. In addition, one or more memories 104, 204 may be connected to one or more processors 102, 202 through various technologies such as wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, control information, radio signals/channels, and the like mentioned in the methods and/or operation flow charts of this document to one or more other devices. One or more transceivers (106, 206) may receive user data, control information, radio signals/channels, etc. mentioned in the description, functions, procedures, suggestions, methods and/or operation flow charts disclosed in this document from one or more other devices. have. For example, one or more transceivers 106 and 206 may be connected to one or more processors 102 and 202, and may transmit and receive wireless signals. For example, one or more processors 102, 202 may control one or more transceivers 106, 206 to transmit user data, control information, or radio signals to one or more other devices. In addition, one or more processors 102, 202 may control one or more transceivers 106, 206 to receive user data, control information, or radio signals from one or more other devices. In addition, one or more transceivers (106, 206) may be connected with one or more antennas (108, 208), and one or more transceivers (106, 206) through one or more antennas (108, 208), the description and functionality disclosed in this document. It may be set to transmit and receive user data, control information, radio signals/channels, and the like mentioned in a procedure, a proposal, a method and/or an operation flowchart. In this document, one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (eg, antenna ports). One or more transceivers (106, 206) in order to process the received user data, control information, radio signal / channel, etc. using one or more processors (102, 202), the received radio signal / channel, etc. in the RF band signal. It can be converted into a baseband signal. One or more transceivers 106 and 206 may convert user data, control information, radio signals/channels, etc. processed using one or more processors 102 and 202 from a baseband signal to an RF band signal. To this end, one or more of the transceivers 106 and 206 may include (analog) oscillators and/or filters.

28 shows another example of a wireless device applied to the present invention. The wireless device may be implemented in various forms according to use-examples/services (see FIG. 26).

Referring to FIG. 28, the wireless devices 100 and 200 correspond to the wireless devices 100 and 200 of FIG. 27, and various elements, components, units/units, and/or modules ) Can be composed of. For example, the wireless devices 100 and 200 may include a communication unit 110, a control unit 120, a memory unit 130, and an additional element 140. The communication unit may include a communication circuit 112 and a transceiver(s) 114. For example, the communication circuit 112 may include one or more processors 102 and 202 and/or one or more memories 104 and 204 of FIG. 27. For example, the transceiver(s) 114 may include one or more transceivers 106,206 and/or one or more antennas 108,208 of FIG. 27. The control unit 120 is electrically connected to the communication unit 110, the memory unit 130, and the additional element 140 and controls all operations of the wireless device. For example, the controller 120 may control the electrical/mechanical operation of the wireless device based on the program/code/command/information stored in the memory unit 130. In addition, the control unit 120 transmits the information stored in the memory unit 130 to an external (eg, other communication device) through the communication unit 110 through a wireless/wired interface, or through the communication unit 110 to the outside (eg, Information received through a wireless/wired interface from another communication device) may be stored in the memory unit 130. Accordingly, the specific operation process of the control unit 120 and the program/code/command/information stored in the memory unit 130 according to the present invention are at least one operation of the processors 102 and 202 of FIG. 27 and the memory 104 and 204. ) May correspond to at least one operation.

The additional element 140 may be variously configured according to the type of wireless device. For example, the additional element 140 may include at least one of a power unit/battery, an I/O unit, a driving unit, and a computing unit. Although not limited to this, wireless devices include robots (FIGS. 26, 100a), vehicles (FIGS. 26, 100b-1, 100b-2), XR devices (FIGS. 26, 100c), portable devices (FIGS. 26, 100d), and home appliances. (Figure 26, 100e), IoT device (Figure 26, 100f), digital broadcasting terminal, hologram device, public safety device, MTC device, medical device, fintech device (or financial device), security device, climate/environment device, It may be implemented in the form of an AI server/device (FIGS. 26 and 400 ), a base station (FIGS. 26 and 200 ), and a network node. The wireless device can be used in a mobile or fixed location depending on the use-example/service.

In FIG. 28, various elements, components, units/units, and/or modules in the wireless devices 100 and 200 may be entirely interconnected through a wired interface, or at least some may be wirelessly connected through the communication unit 110. For example, in the wireless devices 100 and 200, the control unit 120 and the communication unit 110 are connected by wire, and the control unit 120 and the first unit (eg, 130, 140) are connected through the communication unit 110. Can be connected wirelessly. In addition, each element, component, unit/unit, and/or module in the wireless device 100 and 200 may further include one or more elements. For example, the controller 120 may be configured with one or more processor sets. For example, the control unit 120 may be composed of a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphic processing processor, and a memory control processor. As another example, the memory unit 130 includes random access memory (RAM), dynamic RAM (DRAM), read only memory (ROM), flash memory, volatile memory, and non-volatile memory. volatile memory) and/or a combination thereof.

Hereinafter, an implementation example of FIG. 28 will be described in more detail with reference to the drawings.

29 illustrates a portable device applied to the present invention. Portable devices may include smart phones, smart pads, wearable devices (eg, smart watches, smart glasses), and portable computers (eg, notebook computers). The portable device may be referred to as a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a subscriber station (SS), an advanced mobile station (AMS), or a wireless terminal (WT).

Referring to FIG. 29, the portable device 100 includes an antenna unit 108, a communication unit 110, a control unit 120, a memory unit 130, a power supply unit 140a, an interface unit 140b, and an input/output unit 140c. ) Can be included. The antenna unit 108 may be configured as a part of the communication unit 110. Blocks 110 to 130/140a to 140c correspond to blocks 110 to 130/140 of FIG. 28, respectively.

The communication unit 110 may transmit and receive signals (eg, data, control signals, etc.) with other wireless devices and base stations. The controller 120 may perform various operations by controlling components of the portable device 100. The controller 120 may include an application processor (AP). The memory unit 130 may store data/parameters/programs/codes/commands required for driving the portable device 100. Also, the memory unit 130 may store input/output data/information, and the like. The power supply unit 140a supplies power to the portable device 100 and may include a wired/wireless charging circuit, a battery, and the like. The interface unit 140b may support connection between the portable device 100 and other external devices. The interface unit 140b may include various ports (eg, audio input/output ports, video input/output ports) for connection with external devices. The input/output unit 140c may receive or output image information/signal, audio information/signal, data, and/or information input from a user. The input/output unit 140c may include a camera, a microphone, a user input unit, a display unit 140d, a speaker, and/or a haptic module.

For example, in the case of data communication, the input/output unit 140c acquires information/signals (eg, touch, text, voice, image, video) input from the user, and the obtained information/signals are stored in the memory unit 130. Can be saved. The communication unit 110 may convert information/signals stored in the memory into wireless signals, and may directly transmit the converted wireless signals to other wireless devices or to a base station. In addition, after receiving a radio signal from another radio device or a base station, the communication unit 110 may restore the received radio signal to the original information/signal. After the restored information/signal is stored in the memory unit 130, it may be output in various forms (eg, text, voice, image, video, heptic) through the input/output unit 140c.

30 illustrates a vehicle or an autonomous vehicle to which the present invention is applied. The vehicle or autonomous vehicle may be implemented as a mobile robot, a vehicle, a train, an aerial vehicle (AV), or a ship.

Referring to FIG. 30, the vehicle or autonomous vehicle 100 includes an antenna unit 108, a communication unit 110, a control unit 120, a driving unit 140a, a power supply unit 140b, a sensor unit 140c, and autonomous driving. It may include a unit (140d). The antenna unit 108 may be configured as a part of the communication unit 110. Blocks 110/130/140a to 140d correspond to blocks 110/130/140 of FIG. 28, respectively.

The communication unit 110 may transmit and receive signals (eg, data, control signals, etc.) with external devices such as other vehicles, base stations (e.g. base stations, roadside base stations, etc.), and servers. The controller 120 may perform various operations by controlling elements of the vehicle or the autonomous vehicle 100. The control unit 120 may include an Electronic Control Unit (ECU). The driving unit 140a may cause the vehicle or the autonomous vehicle 100 to travel on the ground. The driving unit 140a may include an engine, a motor, a power train, a wheel, a brake, a steering device, and the like. The power supply unit 140b supplies power to the vehicle or the autonomous vehicle 100, and may include a wired/wireless charging circuit, a battery, and the like. The sensor unit 140c may obtain vehicle status, surrounding environment information, user information, and the like. The sensor unit 140c is an IMU (inertial measurement unit) sensor, a collision sensor, a wheel sensor, a speed sensor, an inclination sensor, a weight detection sensor, a heading sensor, a position module, and a vehicle advancement. /Reverse sensor, battery sensor, fuel sensor, tire sensor, steering sensor, temperature sensor, humidity sensor, ultrasonic sensor, illumination sensor, pedal position sensor, etc. may be included. The autonomous driving unit 140d is a technology for maintaining a driving lane, a technology for automatically adjusting the speed such as adaptive cruise control, a technology for automatically driving along a predetermined route, and for driving by automatically setting a route when a destination is set. Technology, etc. can be implemented.

For example, the communication unit 110 may receive map data and traffic information data from an external server. The autonomous driving unit 140d may generate an autonomous driving route and a driving plan based on the acquired data. The controller 120 may control the driving unit 140a so that the vehicle or the autonomous driving vehicle 100 moves along the autonomous driving path according to the driving plan (eg, speed/direction adjustment). During autonomous driving, the communication unit 110 asynchronously/periodically acquires the latest traffic information data from an external server, and may acquire surrounding traffic information data from surrounding vehicles. In addition, during autonomous driving, the sensor unit 140c may acquire vehicle state and surrounding environment information. The autonomous driving unit 140d may update the autonomous driving route and the driving plan based on the newly acquired data/information. The communication unit 110 may transmit information about a vehicle location, an autonomous driving route, and a driving plan to an external server. The external server may predict traffic information data in advance using AI technology or the like based on information collected from the vehicle or autonomously driving vehicles, and may provide the predicted traffic information data to the vehicle or autonomously driving vehicles.

31 illustrates a signal processing circuit for a transmission signal.

Referring to FIG. 31, the signal processing circuit 1000 may include a scrambler 1010, a modulator 1020, a layer mapper 1030, a precoder 1040, a resource mapper 1050, and a signal generator 1060. have. Although not limited thereto, the operations/functions of FIG. 31 may be performed in the processors 102 and 202 and/or the transceivers 106 and 206 of FIG. 27. The hardware elements of FIG. 31 may be implemented in the processors 102 and 202 and/or the transceivers 106 and 206 of FIG. 27. For example, blocks 1010 to 1060 may be implemented in the processors 102 and 202 of FIG. 27. Further, blocks 1010 to 1050 may be implemented in the processors 102 and 202 of FIG. 27, and block 1060 may be implemented in the transceivers 106 and 206 of FIG. 27.

The codeword may be converted into a wireless signal through the signal processing circuit 1000 of FIG. 31. Here, the codeword is an encoded bit sequence of an information block. The information block may include a transport block (eg, a UL-SCH transport block, a DL-SCH transport block). The radio signal may be transmitted through various physical channels (eg, PUSCH, PDSCH).

Specifically, the codeword may be converted into a scrambled bit sequence by the scrambler 1010. The scramble sequence used for scramble is generated based on an initialization value, and the initialization value may include ID information of a wireless device. The scrambled bit sequence may be modulated by the modulator 1020 into a modulation symbol sequence. The modulation scheme may include pi/2-Binary Phase Shift Keying (pi/2-BPSK), m-Phase Shift Keying (m-PSK), m-Quadrature Amplitude Modulation (m-QAM), and the like. The complex modulation symbol sequence may be mapped to one or more transport layers by the layer mapper 1030. The modulation symbols of each transport layer may be mapped to the corresponding antenna port(s) by the precoder 1040 (precoding). The output z of the precoder 1040 can be obtained by multiplying the output y of the layer mapper 1030 by the N*M precoding matrix W. Here, N is the number of antenna ports, and M is the number of transmission layers. Here, the precoder 1040 may perform precoding after performing transform precoding (eg, DFT transform) on complex modulation symbols. Also, the precoder 1040 may perform precoding without performing transform precoding.

The resource mapper 1050 may map modulation symbols of each antenna port to a time-frequency resource. The time-frequency resource may include a plurality of symbols (eg, CP-OFDMA symbols, DFT-s-OFDMA symbols) in the time domain, and may include a plurality of subcarriers in the frequency domain. The signal generator 1060 generates a radio signal from the mapped modulation symbols, and the generated radio signal may be transmitted to another device through each antenna. To this end, the signal generator 1060 may include an Inverse Fast Fourier Transform (IFFT) module and a Cyclic Prefix (CP) inserter, a Digital-to-Analog Converter (DAC), a frequency uplink converter, and the like. .

The signal processing process for the received signal in the wireless device may be configured in reverse of the signal processing process 1010 to 1060 of FIG. 31. For example, a wireless device (eg, 100 and 200 in FIG. 27) may receive a wireless signal from the outside through an antenna port/transmitter. The received radio signal may be converted into a baseband signal through a signal restorer. To this end, the signal restorer may include a frequency downlink converter, an analog-to-digital converter (ADC), a CP canceller, and a Fast Fourier Transform (FFT) module. Thereafter, the baseband signal may be reconstructed into a codeword through a resource de-mapper process, a postcoding process, a demodulation process, and a de-scramble process. The codeword may be restored to an original information block through decoding. Accordingly, a signal processing circuit (not shown) for a received signal may include a signal restorer, a resource demapper, a postcoder, a demodulator, a descrambler, and a decoder.

The embodiments described above are those in which components and features of the present invention are combined in a predetermined form. Each component or feature should be considered optional unless explicitly stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, it is also possible to construct an embodiment of the present invention by combining some components and/or features. The order of operations described in the embodiments of the present invention may be changed. Some configurations or features of one embodiment may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is apparent that claims that do not have an explicit citation relationship in the claims may be combined to constitute an embodiment or may be included as a new claim by amendment after filing.

A specific operation described as being performed by a base station in this document may be performed by its upper node in some cases. That is, it is obvious that various operations performed for communication with a terminal in a network comprising a plurality of network nodes including a base station may be performed by the base station or network nodes other than the base station. The base station may be replaced by terms such as a fixed station, gNode B (gNB), Node B, eNode B (eNB), and access point.

It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the features of the present invention. Therefore, the detailed description above should not be construed as restrictive in all respects and should be considered as illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

The method and apparatus for performing the random access process in the wireless communication system as described above have been described focusing on an example applied to the 5th generation NewRAT system, but can be applied to various wireless communication systems other than the 5th generation NewRAT system. Do.

Claims (15)

1. In a method for a UE to perform a random access channel procedure (RACH Procedure) in a wireless communication system,

   Transmitting a message A including a physical random access channel (PRACH) preamble and a physical uplink shared channel (PUSCH) to a base station; And

   In response to the message A, including the step of receiving a message B including contention resolution information from the base station,

   Information on the retransmission of the message A is included in the MAC PDU (Medium Access Control Protocol Data Block) for the random access response (RAR) related to the message B,

   How to perform a random access process.
2. The method of claim 1,

   The information on the retransmission of the message A includes information on whether to retransmit the message A and information on the number of retransmissions of the message A,

   How to perform a random access process.
3. The method of claim 1,

   The information on the retransmission of the message A is indicated based on bits included in reserved bits for a sub-header in the MAC PDU,

   How to perform a random access process.
4. The method of claim 3,

   The information on the retransmission of the message A is used based on the fact that the RAR was not decoded by the terminal,

   How to perform a random access process.
5. The method of claim 4,

   A single bit is used to indicate information on retransmission of the message A,

   Based on the fact that the RAR cannot be decoded by the terminal and the value indicated by the single bit is 1, retransmission of the message A is performed,

   How to perform a random access process.
6. The method of claim 4,

   A plurality of bits are used to indicate information on retransmission of the message A,

   Retransmission of the message A is performed based on the fact that the RAR is not decoded by the terminal and the value indicated by the plurality of bits is not 0,

   How to perform a random access process.
7. The method of claim 6,

   The number of times the retransmission of the message A can be performed is based on a value indicated by the plurality of bits,

   How to perform a random access process.
8. In an apparatus for performing a random access channel procedure (RACH Procedure) in a wireless communication system,

   At least one processor; And

   At least one memory that is operably connected to the at least one processor and stores instructions for causing the at least one processor to perform a specific operation when executed; and

   The specific operation is,

   Transmitting a message A including a physical random access channel (PRACH) preamble and a physical uplink shared channel (PUSCH); And

   In response to the message A, comprising the step of receiving a message B including contention resolution information,

   Information on the retransmission of the message A is included in the MAC PDU (Medium Access Control Protocol Data Block) for the random access response (RAR) related to the message B,

   Device.
9. The method of claim 8,

   The information on the retransmission of the message A includes information on whether to retransmit the message A and information on the number of retransmissions of the message A,

   Device.
10. The method of claim 8,

    The information on the retransmission of the message A is indicated based on bits included in reserved bits for a sub-header in the MAC PDU,

    Device.
11. The method of claim 10,

    The information on the retransmission of the message A is used based on the fact that the RAR was not decoded by the terminal,

    Device.
12. The method of claim 11,

    A single bit is used to indicate information on retransmission of the message A,

    Based on the fact that the RAR cannot be decoded by the terminal and the value indicated by the single bit is 1, retransmission of the message A is performed,

    Device.
13. The method of claim 11,

    A plurality of bits are used to indicate information on retransmission of the message A,

    Retransmission of the message A is performed based on the fact that the RAR is not decoded by the terminal and the value indicated by the plurality of bits is not 0,

    Device.
14. The method of claim 13,

    The number of times the retransmission of the message A can be performed is based on a value indicated by the plurality of bits,

    Device.
15. In a terminal for performing a random access channel procedure (RACH Procedure) in a wireless communication system,

    At least one transceiver;

    At least one processor; And

    At least one memory that is operably connected to the at least one processor and stores instructions for causing the at least one processor to perform a specific operation when executed; and

    The specific operation is,

    Transmitting a message A including a physical random access channel (PRACH) preamble and a physical uplink shared channel (PUSCH) to a base station; And

    In response to the message A, including the step of receiving a message B including contention resolution information from the base station,

    Information on the retransmission of the message A is included in the MAC PDU (Medium Access Control Protocol Data Block) for the random access response (RAR) related to the message B,

    Terminal.

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