Method and apparatus for performing retransmission based on drop indication in a wireless communication system

Abstract

This disclosure relates to a method for performing operations for a user equipment (UE) in a wireless communication system. Specifically, the method includes the following steps: submitting one or more RLC Service Data Units (SDUs) by a Radio Link Control (RLC) entity of the UE to a Medium Access Control (MAC) entity of the UE, wherein a polling retransmission timer is started based on the submission of one or more RLC SDUs along with polling; receiving, by the RLC entity, a discard indication for at least one of the submitted RLC SDUs by a Packet Data Convergence Protocol (PDCP) entity of the UE; selecting an RLC SDU for retransmission from the submitted one or more RLC SDUs other than the at least one RLC SDU indicated by the discard indication upon the expiration of the polling retransmission timer; and submitting the selected RLC SDU for retransmission to a MAC entity.

Description

Technical Field

[0001] This disclosure relates to a wireless communication system, and more specifically, to a method and apparatus for performing retransmission based on a drop indication in a wireless communication system. Background Technology

[0002] The introduction of new radio communication technologies has led to an increase in the number of user equipments (UEs) that a base station (BS) provides services to within a designated resource area, and also an increase in the amount of control information and data that the BS sends to the UEs. Since the resources typically available for communication between the BS and the UE are limited, new technologies are needed to enable the BS to efficiently receive / transmit uplink / downlink data and / or uplink / downlink control information using limited radio resources. Specifically, overcoming latency has become a significant challenge in applications where performance is critically dependent on delay. Summary of the Invention

[0003] Technical issues

[0004] Therefore, the purpose of this disclosure is to provide a method and apparatus for performing retransmission based on a drop indication in a wireless communication system.

[0005] Technical plan

[0006] The object of this disclosure can be achieved by a method comprising the following steps: a Radio Link Control (RLC) entity of a UE submits one or more RLC Service Data Units (SDUs) to a Media Access Control (MAC) entity of a User Equipment (UE), wherein a polling retransmission timer is started based on the submission of one or more RLC SDUs along with polling; the RLC entity receives a discard indication for at least one RLC SDU among the submitted one or more RLC SDUs from a Packet Data Convergence Protocol (PDCP) entity of the UE; upon the expiration of the polling retransmission timer, the RLC entity selects an RLC SDU for retransmission from the submitted one or more RLC SDUs other than the at least one RLC SDU indicated by the discard indication; and the RLC entity submits the selected RLC SDU for retransmission to the MAC entity.

[0007] Furthermore, a user equipment (UE) in a wireless communication system is proposed, the UE comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least the following operations: submitting one or more RLC Service Data Units (SDUs) by the UE's Radio Link Control (RLC) entity to the UE's Media Access Control (MAC) entity, wherein a polling retransmission timer is started based on the submission of one or more RLC SDUs along with polling; receiving, by the RLC entity, a discard indication for at least one of the submitted one or more RLC SDUs from the UE's Packet Data Convergence Protocol (PDCP) entity; selecting an RLC SDU for retransmission from the submitted one or more RLC SDUs other than the at least one RLC SDU indicated by the discard indication upon the expiration of the polling retransmission timer; and submitting the RLCSDU for the retransmission selection to the MAC entity.

[0008] Preferably, the RLC SDU for retransmission is selected from one or more submitted RLC SDUs that have never been indicated by a drop instruction and have not yet been confirmed.

[0009] Preferably, the RLC SDU for retransmission is selected based on both the transmission buffer and the retransmission buffer being empty, or based on the inability to send new RLC SDUs or RLC SDU segments due to window pauses.

[0010] Preferably, the RLC SDU for retransmission selection is submitted by restarting the polling of the retransmission timer.

[0011] Preferably, the step of selecting the RLC SDU for retransmission includes selecting from one or more submitted RLC SDUs, other than the RLC SDU indicated by the drop instruction, the RLCSDU with the minimum remaining time until it is dropped.

[0012] Preferably, the step of selecting the RLC SDU for retransmission includes selecting the RLC SDU for retransmission indicated by the delay key indication from one or more submitted RLC SDUs, other than the at least one RLC SDU indicated by the drop indication.

[0013] Those skilled in the art will understand that the effects achievable through this disclosure are not limited to those specifically described above, and that other advantages of this disclosure will become clearer from the following detailed description.

[0014] Beneficial effects

[0015] According to this disclosure, when the polling retransmission timer expires, the UE can select the RLC SDU for retransmission based on its remaining time or a discard indication received from the upper layer. Therefore, this prevents unnecessary retransmission of old data and allows for the timely transmission of urgent XR data to the network, which can enhance the user's experience with XR services. It also avoids wasting radio resources.

[0016] The effects that can be obtained from this disclosure are not limited to those described above. Furthermore, those skilled in the art to which this disclosure pertains will clearly understand other effects not mentioned in the following description. Attached Figure Description

[0017] The accompanying drawings, included to provide a further understanding of this disclosure, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure: Figure 1 An example of a communication system 1 that applies the implementation of this disclosure is shown; Figure 2 This is a block diagram illustrating an example of a communication device capable of performing the methods according to this disclosure; Figure 3 An example of a frame structure in a 3GPP-based wireless communication system is shown; Figure 4 An example of a protocol stack in a wireless communication system based on the 3rd Generation Partnership Project (3GPP) is shown; Figure 5 An example of data flow in a 3GPP New Radio (NR) system is shown; Figure 6 Examples of time-domain resource allocation via PDSCH and PUSCH via PDCCH are shown. Figure 7 An example of physical layer processing on the sending side is shown; Figure 8 An example of physical layer processing on the receiving side is shown; Figure 9 A first example of performing a retransmission according to this disclosure is shown; Figure 10 A second example of performing retransmission according to this disclosure is shown; Figure 11 A third example of performing retransmission according to this disclosure is shown; and Figure 12 A flowchart is shown for performing the operations according to this disclosure. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The detailed description given below with reference to the drawings is intended to explain exemplary embodiments of the present disclosure, and not to illustrate the only embodiments that may be implemented according to the present disclosure. The following detailed description includes specific details to provide a thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that the present disclosure may be practiced without these specific details.

[0019] The following technologies, devices, and systems can be applied to a variety of wireless multiple access systems. Examples of multiple access systems include Code Division Multiple Access (CDMA) systems, Frequency Division Multiple Access (FDMA) systems, Time Division Multiple Access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems, and Multi-Carrier Frequency Division Multiple Access (MC-FDMA) systems. CDMA can be implemented using radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented using radio technologies such as Global System for Mobile Communications (GSM), Universal Packet Radio Service (GPRS), or Enhanced Data Rate GSM Evolution (EDGE). OFDMA can be implemented using radio technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) is part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE uses OFDMA in DL and SC-FDMA in UL. LTE-Advanced (LTE-A) is an evolution of 3GPP LTE.

[0020] For ease of description, the implementation of this disclosure is primarily described with respect to 3GPP-based wireless communication systems. However, the technical features of this disclosure are not limited thereto. For example, although the following detailed description is based on a mobile communication system corresponding to a 3GPP-based wireless communication system, aspects of this disclosure that are not limited to 3GPP-based wireless communication systems are applicable to other mobile communication systems. For terms and techniques used in this disclosure that are not specifically described in this disclosure, reference can be made to wireless communication standards documents published prior to this disclosure. For example, the following documents may be referenced.

[0021] 3GPP LTE

[0022] - 3GPP TS 36.211: Physical Channels and Modulation

[0023] - 3GPP TS 36.212: Multiplexing and Channel Coding

[0024] - 3GPP TS 36.213: Physical Layer Procedures

[0025] - 3GPP TS 36.214: Physical Layer; Measurement

[0026] - 3GPP TS 36.300: General Description

[0027] - 3GPP TS 36.304: Procedures for User Equipment (UE) in Idle Mode

[0028] - 3GPP TS 36.314: Layer 2 - Measurement

[0029] - 3GPP TS 36.321: Media Access Control (MAC) Protocol

[0030] - 3GPP TS 36.322: Radio Link Control (RLC) Protocol

[0031] - 3GPP TS 36.323: Packet Data Convergence Protocol (PDCP)

[0032] - 3GPP TS 36.331: Radio Resource Control (RRC) Protocol

[0033] 3GPP NR (e.g., 5G)

[0034] - 3GPP TS 38.211: Physical Channels and Modulation

[0035] - 3GPP TS 38.212: Multiplexing and Channel Coding

[0036] - 3GPP TS 38.213: Physical layer procedures for control

[0037] - 3GPP TS 38.214: Physical Layer Procedures for Data

[0038] - 3GPP TS 38.215: Physical Layer Measurements

[0039] - 3GPP TS 38.300: General Description

[0040] - 3GPP TS 38.304: Procedures for User Equipment (UE) in Idle Mode and RRC Inactive State

[0041] - 3GPP TS 38.321: Media Access Control (MAC) Protocol

[0042] - 3GPP TS 38.322: Radio Link Control (RLC) Protocol

[0043] - 3GPP TS 38.323: Packet Data Convergence Protocol (PDCP)

[0044] - 3GPP TS 38.331: Radio Resource Control (RRC) Protocol

[0045] - 3GPP TS 37.324: Service Data Adaptation Protocol (SDAP)

[0046] - 3GPP TS 37.340: Multiple Connectivity; General Description

[0047] In this disclosure, a User Equipment (UE) can be a fixed or mobile device. Examples of UEs include various devices that transmit user data and / or various control information to and from a Base Station (BS). In this disclosure, a BS generally refers to a fixed station that communicates with and / or exchanges various data and control information with the UE and other BSs. A BS can be referred to as an Advanced Base Station (ABS), Node B (NB), Evolved Node B (eNB), Base Transceiver System (BTS), Access Point (AP), Processing Server (PS), etc. Specifically, a BS for UMTS is referred to as an NB, a BS for Enhanced Packet Core (EPC) / Long Term Evolution (LTE) systems is referred to as an eNB, and a BS for New Radio (NR) systems is referred to as a gNB.

[0048] In this disclosure, a node refers to a point capable of transmitting / receiving radio signals by communicating with a UE. Various types of BSs can be used as nodes regardless of their terminology. For example, a BS, Node B (NB), e-Node B (eNB), picocell eNB (PeNB), home eNB (HeNB), repeater, transponder, etc., can be nodes. Alternatively, a node may not be a BS. For example, a node can be a Radio Remote Headend (RRH) or Radio Remote Unit (RRU). The power level of an RRH or RRU is typically lower than that of a BS. Since an RRH or RRU (hereinafter referred to as RRH / RRU) is typically connected to a BS via a dedicated line such as fiber optic cable, cooperative communication between an RRH / RRU and a BS can be performed smoothly compared to cooperative communication between BSs connected via radio lines. Each node is equipped with at least one antenna. The antenna may include a physical antenna, an antenna port, or a dummy antenna.

[0049] In this disclosure, the term "cell" can refer to a geographical area to which one or more nodes provide a communication system, or it can refer to radio resources. A "cell" of a geographical area can be understood as the coverage area to which a node can provide services using a carrier, and a "cell" as a radio resource (e.g., time-frequency resource) is associated with a bandwidth (BW) as a frequency range configured by a carrier. A "cell" associated with radio resources is defined by a combination of downlink and uplink resources (e.g., a combination of downlink (DL) component carriers (CC) and uplink (UL) CCs). A cell can be configured by downlink resources only, or it can be configured by both downlink and uplink resources. Since the DL coverage area, which is the range to which a node can transmit valid signals, and the UL coverage area, which is the range to which a node can receive valid signals from a UE, depend on the carrier carrying the signal, a node's coverage area can be associated with the coverage area of ​​the "cell" of the radio resources used by the node. Therefore, the term "cell" can sometimes be used to refer to the service coverage area of ​​a node, sometimes to a radio resource, or sometimes to the range to which a signal using a radio resource can reach with effective strength.

[0050] In this disclosure, the Physical Downlink Control Channel (PDCCH) and the Physical Downlink Shared Channel (PDSCH) refer to a set of time-frequency resources or resource elements (REs) carrying downlink control information (DCI), and a set of time-frequency resources or REs carrying downlink data, respectively. Furthermore, the Physical Uplink Control Channel (PUCCH), the Physical Uplink Shared Channel (PUSCH), and the Physical Random Access Channel (PRACH) refer to a set of time-frequency resources or REs carrying uplink control information (UCI), a set of time-frequency resources or REs carrying uplink data, and a set of time-frequency resources or REs carrying random access signals, respectively.

[0051] In carrier aggregation (CA), two or more radio resources (CCs) are aggregated. A UE can simultaneously receive or transmit on one or more CCs, depending on its capabilities. Both continuous and non-contiguous CCs support CA. When CA is configured, the UE has only one Radio Resource Control (RRC) connection with the network. During RRC connection establishment / re-establishment / handover, one serving cell provides Non-Access Stratum (NAS) mobility information, and during RRC connection re-establishment / handover, one serving cell provides security input. This cell is called the primary cell (PCell). The PCell is the cell operating on the primary frequency, where the UE performs the initial connection establishment procedure or initiates the connection re-establishment procedure. Depending on the UE's capabilities, secondary cells (SCells) can be configured to form a group of serving cells together with the PCell. An SCell is a cell that provides additional radio resources on a special cell. Therefore, a group of serving cells configured for a UE always consists of one PCell and one or more SCells. In this disclosure, for dual connectivity (DC) operation, the term "special cell" refers to the PCell of the primary cell group (MCG) or the PSCell of the secondary cell group (SCG), and otherwise the term "special cell" refers to the PCell. SpCell supports Physical Uplink Control Channel (PUCCH) transmission and contention-based random access, and is always active. MCG is a set of serving cells associated with the primary node, including the SpCell (PCell) and one or more optional SCells. SCG is a subset of serving cells associated with the secondary node, including the PSCell and zero or more SCells, for a UE configured with a DC. For a UE in RRC CONNECTED without a CA / DC, there is only one serving cell consisting of the PCell. For a UE in RRC_CONNECTED with a CA / DC, the term "serving cell" is used to refer to a set of cells consisting of the SpCell and all SCells.

[0052] MCG is a set of serving cells associated with a primary BS that terminates at least an S1-MME, and SCG is a set of serving cells associated with a secondary BS that provides additional radio resources to the UE but is not a primary BS. SCG includes a primary SCell (PSCell) and one or more optional SCells. In the DC, two MAC entities are configured in the UE: one for the MCG and one for the SCG. Each MAC entity is configured by the RRC with serving cells supporting PUCCH transmission and contention-based random access. In this disclosure, the term SpCell refers to such a cell, while the term SCell refers to other serving cells. Depending on whether the MAC entity is associated with the MCG or the SCG, the term SpCell refers to the PCell of the MCG or the PSCell of the SCG.

[0053] In this disclosure, monitoring a channel means attempting to decode a channel. For example, monitoring the Physical Downlink Control Channel (PDCCH) means attempting to decode the PDCCH (or a PDCCH candidate).

[0054] In this disclosure, “C-RNTI” refers to cell RNTI, “SI-RNTI” refers to system information RNTI, “P-RNTI” refers to paging RNTI, “RA-RNTI” refers to random access RNTI, “SC-RNTI” refers to single cell RNTI, “SL-RNTI” refers to sidelink RNTI, “SPS C-RNTI” refers to semi-persistent scheduling C-RNTI, and “CS-RNTI” refers to configured scheduling RNTI.

[0055] Figure 1 An example of a communication system 1 that applies the implementation of the present disclosure is shown.

[0056] The three main demand categories for 5G include: (1) enhanced mobile broadband (eMBB), (2) massive machine-type communications (mMTC), and (3) ultra-reliable and low-latency communications (URLLC).

[0057] Some use cases may require multiple categories for optimization, while others can focus on just one key performance indicator (KPI). 5G supports a wide variety of such use cases using flexible and reliable methods.

[0058] eMBB goes far beyond basic mobile internet access and covers a wealth of two-way work, media, and entertainment applications in the cloud and augmented reality. Data is one of the core driving forces of 5G, and for the first time in the 5G era, dedicated voice services may not be provided. In 5G, voice is expected to be simply processed as an application using the data connection provided by the communication system. The main reason for the increased service capacity is the increase in content size and the increase in the number of applications requiring high data transmission rates. As more and more devices connect to the internet, streaming services (audio and video), conversational video, and mobile internet access will be used more widely. These many applications require always-on connectivity to push real-time information and alerts to users. Cloud storage and applications are rapidly increasing in mobile communication platforms and can be applied to both work and entertainment. Cloud storage is a special use case for accelerating the growth of uplink data transmission rates. 5G is also used for remote work in the cloud. When using haptic interfaces, 5G requires much lower end-to-end latency to maintain a good user experience. Entertainment, such as cloud gaming and video streaming, is another core element increasing the demand for mobile broadband capabilities. Entertainment is essential for smartphones and tablets anywhere, including in highly mobile environments such as trains, vehicles, and airplanes. Other use cases include augmented reality for entertainment and information retrieval. In this case, augmented reality requires very low latency and instantaneous data capacity.

[0059] Additionally, one of the most anticipated 5G use cases involves the ability to seamlessly connect embedded sensors across all sectors, namely, mMTC. The expected number of potential IoT devices is projected to reach 204 billion by 2020. Industrial IoT is one of the key categories performing key roles in enabling smart cities, asset tracking, smart utilities, agriculture, and security infrastructure through 5G.

[0060] URLLC encompasses new services that will transform industry, such as autonomous vehicles, through remote control of the main infrastructure and ultra-reliable / available low-latency links. Levels of reliability and latency are essential for controlling smart grids, automating industry, enabling robotics, and controlling and adapting drones.

[0061] 5G is the means to deliver streams assessed at hundreds of megabits per second to gigabits per second and can complement fiber-to-the-home (FTTH) and wired broadband (or DOCSIS). Such speeds are needed to deliver TVs at 4K or higher resolutions (6K, 8K, and more), as well as virtual reality and augmented reality. Virtual reality (VR) and augmented reality (AR) applications include almost immersive motion games. Specific applications may require special network configurations. For example, for VR games, game companies need to integrate their core servers into the network operator's edge network servers to minimize latency.

[0062] The automotive industry, along with numerous use cases for mobile communications in vehicles, is expected to be a significant new driving force in 5G. For example, passenger entertainment requires high concurrent capacity and highly mobile broadband. This is because future users continue to expect high-quality connectivity regardless of their location and speed. Another use case in the automotive sector is AR dashboards. AR dashboards allow drivers to identify objects in the dark in addition to those seen through the windshield and display distances and movement of objects by overlaying information spoken to the driver. In the future, wireless modules will enable communication between vehicles, information exchange between vehicles and supporting infrastructure, and information exchange between vehicles and other connected devices, such as pedestrian-accompanied devices. Safety systems will guide alternative routes, allowing drivers to drive more safely and thus reducing the risk of accidents. The next stage will be remotely controlled or self-driving vehicles. This requires very high reliability and very fast communication between different self-driving vehicles and between vehicles and infrastructure. In the future, self-driving vehicles will perform all driving activities, and drivers will only focus on abnormal traffic that the vehicle cannot recognize. The technological requirements for self-driving vehicles necessitate ultra-low latency and ultra-high reliability, increasing traffic safety to levels that cannot be achieved by humans.

[0063] Smart cities and smart homes / buildings, touted as part of a smart society, will be embedded in high-density wireless sensor networks. These distributed networks of smart sensors will identify conditions for cost- and energy-efficient maintenance in cities or homes. Similar configurations can be implemented for specific homes. All temperature sensors, window and heating controllers, burglar alarms, and home appliances will be wirelessly connected. Many of these sensors are typically low in terms of data transmission rates, power consumption, and cost. However, certain types of devices may require real-time HD video for monitoring.

[0064] The consumption and distribution of energy, including heat and gases, at a higher level necessitates automated control of distribution sensor networks. Smart grids collect information and use digital information and communication technologies to connect sensors to each other, thereby enabling actions based on the collected information. Because this information can include the behavior of supply companies and consumers, smart grids can improve the distribution of fuels such as electricity through methods that are efficient, reliable, economically feasible, production sustainable, and automated. Smart grids can also be considered as another type of sensor network with low latency.

[0065] Mission-critical applications, such as e-health, are one of the use cases for 5G. The health component includes many applications that can benefit from mobile communications. Communication systems can support telemedicine, enabling the delivery of clinical care in remote locations. Telemedicine can help reduce barriers of distance and improve access to healthcare services that are not readily available in remote rural areas. Telemedicine is also used to administer vital treatments and save lives in emergency situations. Mobile communication-based wireless sensor networks can provide remote monitoring and sensing of parameters such as heart rate and blood pressure.

[0066] Wireless and mobile communications are becoming increasingly important in industrial applications. Cabling is costly in terms of installation and maintenance. Therefore, the possibility of replacing cables with reconfigurable wireless links presents an attractive opportunity in many industrial sectors. However, to achieve this replacement, wireless connections need to have similar latency, reliability, and capacity to cables, and simplified wireless connection management is required. When connecting to 5G, low latency and a very low error probability become new requirements.

[0067] Logistics and freight tracking are important use cases for mobile communications, allowing inventory and packages to be tracked anywhere using location-based information systems. Logistics and freight tracking use cases typically require low data rates but demand location information with wide coverage and reliability.

[0068] Reference Figure 1 Communication system 1 includes wireless devices, base stations (BS), and a network. Although Figure 1 An example of a 5G network as a network of communication system 1 is illustrated, but the implementation of this disclosure is not limited to 5G systems and can be applied to future communication systems other than 5G systems.

[0069] The BS and network can be implemented as wireless devices, and a particular wireless device 200a can operate as a BS / network node relative to other wireless devices.

[0070] A wireless device refers to a device that uses a radio access technology (RAT) (e.g., 5G New RAT (NR) or Long Term Evolution LTE) to perform communication, and may be referred to as a communication / wireless / 5G device. Wireless devices may include, but are not limited to, robots 100a, vehicles 100b-1 and 100b-2, extended reality (XR) devices 100c, handheld devices 100d, home appliances 100e, Internet of Things (IoT) devices 100f, and artificial intelligence (AI) devices / servers 400. For example, a vehicle may include a vehicle with wireless communication capabilities, an autonomous vehicle, and a vehicle capable of performing communication between vehicles. A vehicle may include an unmanned aerial vehicle (UAV) (e.g., a drone). XR devices may include augmented reality (AR) / virtual reality (VR) / mixed reality (MR) devices, and may take the form of a head-up display (HMD), a head-up display (HUD) installed in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, digital signage, a vehicle, a robot, etc. Handheld devices may include smartphones, smart tablets, wearable devices (e.g., smartwatches or smart glasses), and computers (e.g., laptops). Home appliances may include TVs, refrigerators, and washing machines. IoT devices may include sensors and smart meters.

[0071] In this disclosure, wireless devices 100a to 100f may be referred to as user equipment (UE). User equipment (UE) may include, for example, cellular phones, smartphones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation systems, tablet PCs, ultrabooks, vehicles, vehicles with autonomous driving capabilities, connected cars, unmanned aerial vehicles (UAVs), artificial intelligence (AI) modules, robots, augmented reality (AR) devices, virtual reality (VR) devices, mixed reality (MR) devices, holographic devices, public safety devices, MTC devices, IoT devices, medical devices, Fintech devices (or financial devices), security devices, weather / environment devices, devices related to 5G services, or devices related to the fourth industrial evolution. Unmanned aerial vehicles (UAVs) may be, for example, aircraft piloted by wireless control signals without human passengers. VR devices may include, for example, devices for realizing objects or backgrounds in a virtual world. AR devices may include, for example, devices implemented by attaching objects or backgrounds in a virtual world to objects or backgrounds in the real world. MR devices can include, for example, devices that integrate virtual world objects or backgrounds into real world objects or backgrounds. Holographic devices can include, for example, devices for creating 360-degree stereoscopic images by recording and reproducing stereoscopic information, utilizing the interference phenomenon of light generated when two lasers, known as holographic imaging, meet. Public safety devices can include, for example, image relay devices or imaging devices wearable on a user's body. MTC devices and IoT devices can be, for example, devices that do not require direct human intervention or manipulation. For example, MTC devices and IoT devices can include smart meters, vending machines, thermometers, smart light bulbs, door locks, or various sensors. Medical devices can be, for example, devices for the purpose of diagnosing, treating, alleviating, curing, or preventing disease. For example, a medical device can be a device for the purpose of diagnosing, treating, alleviating, or correcting damage or injury. For example, a medical device can be a device for the purpose of examining, replacing, or modifying a structure or function. For example, a medical device can be a device for the purpose of regulating pregnancy. For example, medical devices can include devices for treatment, devices for operation, devices for (in vitro) diagnosis, hearing aids, or devices for surgery. Security devices can be, for example, devices installed to prevent potential hazards and maintain security. For example, security devices can be cameras, CCTV, recorders, or black boxes. Fintech devices can be, for example, devices capable of providing financial services such as mobile payments. For example, Fintech devices can include payment devices or point-of-sale (POS) systems. Weather / environment devices can include, for example, devices used to monitor or predict weather / environment.

[0072] Wireless devices 100a to 100f can connect to network 300 via BS 200. AI technology can be applied to wireless devices 100a to 100f, and wireless devices 100a to 100f can connect to AI server 400 via network 300. Network 300 can be configured using 3G networks, 4G (e.g., LTE) networks, 5G (e.g., NR) networks, and super 5G networks. Although wireless devices 100a to 100f can communicate with each other via BS 200 / network 300, wireless devices 100a to 100f can also perform direct communication with each other without going through the BS / network (e.g., sidelink communication). For example, vehicles 100b-1 and 100b-2 can perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). IoT devices (e.g., sensors) can perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0073] Wireless communication / connections 150A and 150b can be established between wireless devices 100a to 100f / BS 200-BS 200. In this document, wireless communication / connections can be established via various RATs (e.g., 5G NR) such as uplink / downlink communication 150a and sidelink communication 150b (or D2D communication). The wireless devices and the BS / wireless devices can transmit / receive radio signals to / from each other via wireless communication / connections 150a and 150b. For example, wireless communication / connections 150a and 150b can transmit / receive signals via various physical channels. To this end, at least a portion of various configuration information configuration processes, various signal processing processes (e.g., channel coding / decoding, modulation / demodulation, and resource mapping / demapping), and resource allocation processes for transmitting / receiving radio signals can be performed based on various proposals of this disclosure.

[0074] Figure 2 This is a block diagram illustrating an example of a communication device capable of performing the methods according to this disclosure.

[0075] Reference Figure 2 The first wireless device 100 and the second wireless device 200 can transmit / receive radio signals to / from external devices via various RATs (e.g., LTE and NR). Figure 2 In this context, {the first wireless device 100 and the second wireless device 200} can be connected with... Figure 1 The {wireless devices 100a to 100f and BS 200} and / or {wireless devices 100a to 100f and wireless devices 100a to 100f} correspond to each other.

[0076] The first wireless device 100 may include one or more processors 102 and one or more memories 104, and additionally include one or more transceivers 106 and / or one or more antennas 108. The processors 102 may control the memories 104 and / or the transceivers 106 and may be configured to implement the functions, processes, and / or methods described in this disclosure. For example, the processors 102 may process information in the memories 104 to generate first information / signals, and then transmit a radio signal including the first information / signals via the transceivers 106. The processors 102 may receive radio signals including second information / signals via the transceivers 106, and then store the information obtained by processing the second information / signals in the memories 104. The memories 104 may be connected to the processors 102 and may store various information related to the operation of the processors 102. For example, the memories 104 may store software code including commands for performing some or all of the processes controlled by the processors 102 or for performing the processes and / or methods described in this disclosure. In this document, processor 102 and memory 104 may be part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). Transceiver 106 may be connected to processor 102 and transmit and / or receive radio signals via one or more antennas 108. Each of transceivers 106 may include a transmitter and / or a receiver. Transceivers 106 may be used interchangeably with radio frequency (RF) units. In this disclosure, a wireless device may refer to a communication modem / circuit / chip.

[0077] The second wireless device 200 may include one or more processors 202 and one or more memories 204, and additionally include one or more transceivers 206 and / or one or more antennas 208. The processors 202 may control the memories 204 and / or the transceivers 206 and may be configured to implement the functions, processes, and / or methods described in this disclosure. For example, the processors 202 may process information in the memories 204 to generate third information / signals, and then transmit radio signals including the third information / signals via the transceivers 206. The processors 202 may receive radio signals including fourth information / signals via the transceivers 206, and then store the information obtained by processing the fourth information / signals in the memories 204. The memories 204 may be connected to the processors 202 and may store various information related to the operation of the processors 202. For example, the memories 204 may store software code including commands for performing some or all of the processes controlled by the processors 202 or for performing the processes and / or methods described in this disclosure. In this document, processor 202 and memory 204 may be part of a communication modem / circuit / chip designed to implement RAT (e.g., LTE or NR). Transceiver 206 may be connected to processor 202 and transmit and / or receive radio signals via one or more antennas 208. Each of transceivers 206 may include a transmitter and / or a receiver. Transceivers 206 may be used interchangeably with RF units. In this disclosure, a wireless device may refer to a communication modem / circuit / chip.

[0078] The hardware elements of wireless devices 100 and 200 will be described in more detail below. One or more protocol layers may be implemented by, but are not limited to, one or more processors 102 and 202. For example, one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, and SDAP). One or more processors 102 and 202 may generate one or more Protocol Data Units (PDUs) and / or one or more Service Data Units (SDUs) according to the functions, procedures, proposals, and / or methods disclosed in this disclosure. One or more processors 102 and 202 may generate messages, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this disclosure. One or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this disclosure and provide the generated signals to one or more transceivers 106 and 206. One or more processors 102 and 202 may receive signals (e.g., baseband signals) from one or more transceivers 106 and 206 and acquire PDUs, SDUs, messages, control information, data, or information in accordance with the functions, processes, proposals, and / or methods disclosed in this disclosure.

[0079] One or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. One or more 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 functions, processes, proposals, and / or methods disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be configured to include modules, processes, or functions. Firmware or software configured to perform the functions, processes, proposals, and / or methods disclosed in this disclosure may be included in one or more processors 102 and 202 or stored in one or more memories 104 and 204 for drive by one or more processors 102 and 202. The functions, processes, proposals, and / or methods disclosed in this disclosure may be implemented using firmware or software in the form of code, commands, and / or command sets.

[0080] One or more memories 104 and 204 may be connected to one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and / or commands. One or more memories 104 and 204 may be configured with read-only memory (ROM), random access memory (RAM), electrically erasable programmable read-only memory (EPROM), flash memory, hard disk drive, registers, cache memory, computer-readable storage media, and / or combinations thereof. One or more memories 104 and 204 may be located internally and / or externally to one or more processors 102 and 202. One or more memories 104 and 204 may be connected to one or more processors 102 and 202 via various technologies such as wired or wireless connections.

[0081] One or more transceivers 106 and 206 can transmit user data, control information, and / or radio signals / channels as mentioned in the methods and / or operation flowcharts of this disclosure to one or more other devices. One or more transceivers 106 and 206 can receive user data, control information, and / or radio signals / channels as mentioned in the functions, processes, proposals, methods, and / or operation flowcharts disclosed in this disclosure from one or more other devices. For example, one or more transceivers 106 and 206 can be connected to one or more processors 102 and 202 and transmit and receive radio signals. For example, one or more processors 102 and 202 can perform control to enable one or more transceivers 106 and 206 to transmit user data, control information, or radio signals to one or more other devices. One or more processors 102 and 202 can perform control to enable one or more transceivers 106 and 206 to receive user data, control information, or radio signals from one or more other devices. One or more transceivers 106 and 206 may be connected to one or more antennas 108 and 208, and one or more transceivers 106 and 206 may be configured to transmit and receive user data, control information, and / or radio signals / channels mentioned in the functional, process, proposal, method, and / or operational flowcharts disclosed in this disclosure via one or more antennas 108 and 208. In this disclosure, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers 106 and 206 may convert received radio signals / channels, etc., from RF band signals to baseband signals for processing by one or more processors 102 and 202. One or more transceivers 106 and 206 may convert user data, control information, radio signals / channels, etc., processed by one or more processors 102 and 202 from baseband signals to RF band signals. For this purpose, one or more transceivers 106 and 206 may include (analog) oscillators and / or filters. For example, transceivers 106 and 206, under the control of processors 102 and 202, may upconvert OFDM baseband signals to a carrier frequency using their (analog) oscillators and / or filters and transmit the upconverted OFDM signal at the carrier frequency. Transceivers 106 and 206 may receive OFDM signals at the carrier frequency and, under the control of processors 102 and 202, downconvert OFDM signals to OFDM baseband signals using their (analog) oscillators and / or filters.

[0082] In the implementations of this disclosure, the UE can be used as a transmitting device in the uplink (UL) and a receiving device in the downlink (DL). In the implementations of this disclosure, the BS can be used as a receiving device in the UL and a transmitting device in the DL. Hereinafter, for ease of description, unless otherwise stated or described, it is generally assumed that the first wireless device 100 is used as the UE and the second wireless device 200 is used as the BS. For example, a processor 102 connected to, installed on, or started in the first wireless device 100 can be configured to perform UE actions according to the implementations of this disclosure or to control the transceiver 106 to perform UE actions according to the implementations of this disclosure. A processor 202 connected to, installed on, or started in the second wireless device 200 can be configured to perform BS actions according to the implementations of this disclosure or to control the transceiver 206 to perform BS actions according to the implementations of this disclosure.

[0083] In this disclosure, at least one memory (e.g., 104 or 204) may store instructions or programs that, when executed, cause at least one processor operatively connected thereto to perform operations according to some embodiments or implementations of this disclosure.

[0084] In this disclosure, a computer-readable storage medium stores at least one instruction or computer program that, when executed by at least one processor, causes at least one processor to perform operations according to some embodiments or implementations of this disclosure.

[0085] In this disclosure, a processing apparatus or device may include at least one processor and at least one computer memory, the at least one computer memory being connected to at least one processor and storing instructions that, when executed, cause at least one processor to perform operations according to some embodiments or implementations of this disclosure.

[0086] Figure 3 An example of a frame structure in a 3GPP-based wireless communication system is shown.

[0087] Figure 3The frame structure shown is merely exemplary, and the number of subframes, the number of time slots, and / or the number of symbols in a frame can vary. In 3GPP-based wireless communication systems, OFDM parameter sets (e.g., subcarrier spacing (SCS), transmission time interval (TTI) durations) can be configured differently across multiple cells aggregated for a UE. For example, if the UE is configured with different SCSs for cells aggregated for cell aggregation, the (absolute time) durations of time resources (e.g., subframes, time slots, or TTIs) comprising the same number of symbols can be different across the aggregated cells. In this document, symbols can include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or Discrete Fourier Transform-Extended-OFDM (DFT-s-OFDM) symbols).

[0088] Reference Figure 3 Downlink and uplink transmissions are organized into frames. Each frame has a T f =10 ms duration. Each frame is divided into two half-frames, each half-frame having a duration of 5 ms. Each half-frame consists of 5 subframes, where the duration T of each subframe is... sf It is 1 ms. Each subframe is divided into time slots, and the number of time slots in a subframe depends on the subcarrier spacing. Each time slot includes 14 or 12 OFDM symbols based on the cyclic prefix (CP). In normal CP, each time slot includes 14 OFDM symbols, and in extended CP, each time slot includes 12 OFDM symbols. The parameter set is based on an exponentially scalable subcarrier spacing Δf = 2. u 15kHz. The following diagram shows the values ​​based on the subcarrier spacing Δf = 2. u The number of OFDM symbols per slot at 15 kHz, the number of slots per frame, and the number of slots per subframe for normal CP.

[0089] [Table 1]

[0090] The following table shows the subcarrier spacing Δf = 2 u The number of OFDM symbols per slot at 15 kHz, the number of slots per frame, and the number of slots per subframe for extended CP.

[0091] [Table 2]

[0092] A time slot comprises multiple symbols (e.g., 14 or 12 symbols) in the time domain. For each set of parameters (e.g., subcarrier spacing) and carrier, a common resource block (CRB) N is generated from the signaling of higher layers (e.g., radio resource control (RRC) signaling). start,u grid Initially, N was defined. size,u grid,x N RB sc Subcarriers and N subframe,u symb A resource grid of N OFDM symbols, where N size,u grid,x N represents the number of resource blocks in the resource grid, where the subscript x represents the downlink DL and the uplink UL. RB sc N is the number of subcarriers in each resource block. In 3GPP-based wireless communication systems, N... RB sc Typically, it is 12. For a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL), there exists a resource grid. The carrier bandwidth N for the subcarrier spacing configuration u is... size,u grid Given by higher-layer parameters (e.g., RRC parameters). Each element in the resource grid for antenna port p and subcarrier spacing configuration u is called a resource element (RE), and a complex symbol can be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index l representing the symbol position relative to a reference point in the time domain. In 3GPP-based wireless communication systems, a resource block is defined by 12 consecutive subcarriers in the frequency domain.

[0093] In 3GPP NR systems, resource blocks are classified into Common Resource Blocks (CRBs) and Physical Resource Blocks (PRBs). CRBs are numbered upwards from 0 in the frequency domain based on subcarrier spacing configuration u. The center of subcarrier 0 in CRB 0 for subcarrier spacing configuration u coincides with "point A," which serves as the common reference point for the resource block grid. In 3GPP NR systems, PRBs are defined within the Bandwidth Part (BWP) and numbered from 0 to N. size BWP,i -1 is the number, where i is the number of the bandwidth section. The physical resource block n within bandwidth section i... PRB With public resource block n CRB The relationship between n is as follows: PRB =n CRB +N size BWP,i , where N size BWP,iA BWP is a common resource block relative to CRB 0. A BWP comprises multiple consecutive resource blocks. A carrier can include up to N (e.g., 5) BWPs. A UE can be configured with one or more BWPs on a given component carrier. Only one BWP can be active at a time among those configured for the UE. The active BWP is defined within the UE's operating bandwidth of the cell.

[0094] The NR band can be defined as two types of frequency ranges, FR1 and FR2. FR2 can also be referred to as millimeter wave (mmW). The frequency range in which NR can operate is shown as described in Table 3.

[0095] [Table 3]

[0096] Figure 4 An example of a protocol stack in a 3GPP-based wireless communication system is shown.

[0097] Specifically, Figure 4 (a) illustrates an example of the user plane protocol stack for the radio interface between the UE and the base station (BS), and Figure 4 (b) illustrates an example of the radio interface control plane protocol stack between the UE and the BS. The control plane refers to the path through which control messages for calls managed by the UE and the network are transmitted. The user plane refers to the path through which data generated in the application layer (e.g., voice data or Internet packet data) is transmitted. See also... Figure 4 (a) The user plane protocol stack can be divided into a first layer (layer 1) (i.e., the physical (PHY) layer) and a second layer (layer 2). See [reference] Figure 4 (b) The control plane protocol stack can be divided into Layer 1 (i.e., the PHY layer), Layer 2, Layer 3 (e.g., the Radio Resource Control (RRC) layer), and the Non-Access Layer (NAS). Layers 1, 2, and 3 are referred to as the Access Layer (AS).

[0098] The NAS control protocol terminates at the Access Management Function (AMF) on the network side and performs functions such as authentication, mobility management, and security control.

[0099] In 3GPP LTE systems, Layer 2 is separated into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data Convergence Protocol (PDCP). In 3GPP New Radio (NR) systems, Layer 2 is separated into the following sublayers: MAC, RLC, PDCP, and SDAP. The PHY layer provides transport channels to the MAC sublayer, the MAC sublayer provides logical channels to the RLC sublayer, the RLC sublayer provides RLC channels to the PDCP sublayer, and the PDCP sublayer provides radio bearers to the SDAP sublayer. The SDAP sublayer provides Quality of Service (QoS) streams to the 5G core network.

[0100] In the 3GPP NR system, the main services and functions of SDAP include: mapping between QoS flows and data radio bearers; and marking QoS flow IDs (QFIs) in both DL and UL packets. A single SDAP protocol entity is configured for each individual PDU session.

[0101] In the 3GPP NR system, the main services and functions of the RRC sublayer include: broadcasting system information related to AS and NAS; paging initiated by the 5G core (5GC) or NG-RAN; establishment, maintenance, and release of RRC connections between the UE and NG-RAN; security functions including key management; establishment, configuration, maintenance, and release of signaling radio bearers (SRB) and data radio bearers (DRB); mobility functions (including: handover and context transfer; UE cell selection and reselection and control of cell selection and reselection; inter-RAT mobility); QoS management functions; control of UE measurement reporting and reporting; detection and recovery of radio link failures; and NAS message transmission from UE to NAS and from NAS to UE.

[0102] In the 3GPP NR system, the main services and functions of the PDCP sublayer for the user plane include: sequence numbering; header compression and decompression: ROHC only; transmission of user data; reordering and duplicate detection; in-order delivery; PDCP PDU routing (in the case of separate bearers); retransmission of PDCP SDUs; encryption, decryption, and integrity protection; PDCP SDU discarding; PDCP re-establishment and data recovery for RLC AM; PDCP status reporting for RLC AM; and PDCP PDU duplication and duplicate discarding indication for lower layers. The main services and functions of the PDCP sublayer for the control plane include: sequence numbering; encryption, decryption, and integrity protection; transmission of control plane data; reordering and duplicate detection; in-order delivery; and PDCP PDU duplication and duplicate discarding indication for lower layers.

[0103] The RLC sublayer supports three transmission modes: Transparent Mode (TM); Unacknowledged Mode (UM); and Acknowledged Mode (AM). RLC configuration is per logical channel and is independent of parameter sets and / or transmission duration. In 3GPP NR systems, the main services and functions of the RLC sublayer depend on the transmission mode and include: transmission of upper-layer PDUs; sequence numbering independent of PDCP (UM and AM); error correction via ARQ (AM only); RLC SDU segmentation (AM and UM) and re-segmentation (AM only); SDU reassembly (AM and UM); duplicate detection (AM only); RLC SDU dropping (AM and UM); RLC reconstruction; and protocol error detection (AM only).

[0104] In the 3GPP NR system, the main services and functions of the MAC sublayer include: mapping between logical channels and transport channels; multiplexing / demultiplexing MAC SDUs belonging to one or different logical channels to / from the transport channel to the physical layer / from the physical layer to transport blocks (TBs); scheduling information reporting; error correction via HARQ (one HARQ entity per cell in the case of carrier aggregation (CA); priority handling between UEs via dynamic scheduling; priority handling between logical channels of a UE via logical channel priority ordering; and padding. A single MAC entity can support multiple parameter sets, transmission timings, and cells. Mapping restrictions in logical channel priority ordering control which parameter set(s), cell(s), and transmission timing(s) a logical channel(s) can use. MAC provides different types of data transmission services. To accommodate different types of data transmission services, various types of logical channels are defined, i.e., each logical channel supports the transmission of a specific type of information. Each logical channel type is defined by the type of information being transmitted. Logical channels are divided into two groups: control channels and traffic channels. Control channels are used only for the transmission of control plane information, and traffic channels are used only for the transmission of user plane information. The Broadcast Control Channel (BCCH) is a downlink logical channel used for broadcasting system control information. The Paging Control Channel (PCCH) is a downlink logical channel that transmits paging information, system information change notifications, and indications of ongoing PWS broadcasts. The Common Control Channel (CCCH) is a logical channel used by UEs without an RRC connection to the network to transmit control information. The Dedicated Control Channel (DCCH) is a point-to-point bidirectional logical channel used by UEs with an RRC connection to transmit dedicated control information between the UE and the network. The Dedicated Traffic Channel (DTCH) is a point-to-point logical channel dedicated to a single UE for transmitting user information. DTCH can exist in both the uplink and downlink. In the downlink, the following connections exist between logical channels and transport channels: BCCH can be mapped to BCH; BCCH can be mapped to Downlink Shared Channel (DL-SCH); PCCH can be mapped to PCH; CCCH can be mapped to DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to DL-SCH. In the uplink, there are the following connections between logical channels and transport channels: CCCH can be mapped to the uplink shared channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

[0105] Figure 5 An example of a data flow in a 3GPP NR system is shown.

[0106] exist Figure 5In this code, "RB" stands for Radio Bearer, and "H" represents the header. Radio bearers are classified into two groups: Data Radio Bearers (DRBs) for user plane data and Signaling Radio Bearers (SRBs) for control plane data. MAC PDUs are sent / received to / from external devices via the PHY layer using radio resources. MAC PDUs arrive at the PHY layer in the form of transport blocks.

[0107] At the PHY layer, the uplink transport channels UL-SCH and RACH are mapped to the Physical Uplink Shared Channel (PUSCH) and Physical Random Access Channel (PRACH), respectively, and the downlink transport channels DL-SCH, BCH, and PCH are mapped to the Physical Downlink Shared Channel (PDSCH), Physical Broadcast Channel (PBCH), and PDSCH, respectively. At the PHY layer, uplink control information (UCI) is mapped to PUCCH, and downlink control information (DCI) is mapped to PDCCH. The UE transmits MAC PDUs related to UL-SCH via PUSCH based on UL grant, and the BS transmits MAC PDUs related to DL-SCH via PDSCH based on DL assignment.

[0108] To transmit the data elements of this disclosure on the UL-SCH, the UE must have uplink resources available to the UE. To receive the data elements of this disclosure on the DL-SCH, the UE must have downlink resources available to the UE. Resource allocation includes time-domain resource allocation and frequency-domain resource allocation. In this disclosure, uplink resource allocation is also referred to as uplink grant, and downlink resource allocation is also referred to as downlink assignment. Uplink grant is either dynamically received by the UE on the PDCCH in a random access response or semi-persistently configured to the UE by RRC. Downlink assignment is either dynamically received by the UE on the PDCCH or semi-persistently configured to the UE by RRC signaling from the BS.

[0109] In UL, the BS can dynamically allocate resources to the UE via the Cell Radio Network Temporary Identifier (C-RNTI) on the PDCCH. The UE constantly monitors the PDCCH to find possible grants for uplink transmissions when its downlink reception is enabled (when configured by Discontinuous Receive (DRX) control activity). Furthermore, by configuring grants, the BS can allocate uplink resources for the initial HARQ transmission to the UE. Two types of configured uplink grants are defined: Type 1 and Type 2. For Type 1, the RRC directly provides the configured uplink grants (including periodicity). For Type 2, the RRC defines the periodicity of the configured uplink grants, and the PDCCH addressed to the configured Scheduling RNTI (CS-RNTI) can signal and activate, or deactivate, the configured uplink grant; that is, the PDCCH addressing to the CS-RNTI indicates implicit reuse of the uplink grant according to the periodicity defined by the RRC until deactivation.

[0110] In DL, the BS can dynamically allocate resources to the UE via the C-RNTI on the PDCCH. The UE constantly monitors the PDCCH to find possible assignments when its downlink reception is enabled (configuration activity is controlled by DRX). Additionally, through semi-persistent scheduling (SPS), the BS can allocate downlink resources to the UE for initial HARQ transmissions: the RRC defines the periodicity of configured downlink assignments, and the PDCCH addressed to the CS-RNTI can signal and activate, or deactivate, the configured downlink assignment. In other words, the PDCCH addressing the CS-RNTI implicitly reuses downlink assignments based on the periodicity defined by the RRC until deactivation.

[0111] Resource allocation via PDCCH (i.e., resource allocation via DCI)

[0112] The PDCCH can be used to schedule DL transmissions on the PDSCH and UL transmissions on the PUSCH. The downlink control information (DCI) on the PDCCH includes: downlink assignment containing at least the modulation and coding scheme (MCS) associated with the DL-SCH (e.g., Modulation and Coding Scheme (MCS) Index IMCS), resource allocation, and hybrid ARQ information; or uplink scheduling authorization containing at least the modulation and coding scheme associated with the UL-SCH, resource allocation, and hybrid ARQ information. The size and purpose of the DCI carried by a PDCCH vary depending on the DCI format. For example, in a 3GPP NR system, DCI format 0_0 or DCI format 0_1 ​​is used for scheduling PUSCHs within a cell, and DCI format 1_0 or DCI format 1_1 is used for scheduling PDSCHs within a cell.

[0113] Figure 6 Examples of PDSCH time domain resource allocation via PDCCH and PUSCH time resource allocation via PDCCH are shown.

[0114] The downlink control information (DCI) carried by the PDCCH for scheduling PDSCH or PUSCH includes the value m of row index m+1 of the allocation table for PDSCH or PUSCH. A predefined default PDSCH time domain allocation A, B, or C is applied as the PDSCH allocation table, or the pdsch-TimeDomainAllocationList configured by RRC is applied. Similarly, a predefined default PUSCH time domain allocation A is applied as the PUSCH allocation table, or the pusch-TimeDomainAllocationList configured by RRC is applied. Which PDSCH time domain resource allocation configuration and which PUSCH time domain resource allocation table is applied is determined according to fixed / predefined rules (e.g., Table 5.1.2.1.1-1 in 3GPP TS 38.214 v15.3.0, Table 6.1.2.1.1-1 in 3GPP TS 38.214 v15.3.0).

[0115] Each index row in the PDSCH time-domain allocation configuration defines a time slot offset. K 0. Start and length indicators SLIV Or define the start symbol directly. S and allocation length L The PUSCH time-domain allocation configuration defines the slot offset K2, the start and length indicator SLIV, or directly defines the start symbol S and allocation length L, as well as the PUSCH mapping type assumed in PUSCH reception. K0 for PDSCH or K2 for PUSCH is the timing difference between a slot with a PDCCH and a slot with a corresponding PDSCH or PUSCH. SLIV is a joint indication of the start symbol S relative to the start of the slot with the PDSCH or PUSCH and the number L of consecutive symbols counted from symbol S. For the PDSCH / PUSCH mapping type, there are two mapping types: mapping type A, where the demodulation reference signal (DMRS) is located in the 3rd or 4th symbol of the slot according to RRC signaling; and mapping type B, where the DMRS is located in the first allocated symbol.

[0116] The scheduling DCI includes a frequency domain resource assignment field that provides assignment information about resource blocks used for PDSCH or PUSCH. For example, the frequency domain resource assignment field can provide the UE with information about the cell for PDSCH or PUSCH transmission, information about the bandwidth portion for PDSCH or PUSCH transmission, and information about the resource blocks for PDSCH or PUSCH transmission.

[0117] Resource allocation via RRC

[0118] As described above, in the uplink, there are two types of transmissions without dynamic grants: Configured Grant Type 1, where the uplink grant is provided by the RRC and stored as a configured grant; and Configured Grant Type 2, where the uplink grant is provided by the PDCCH, and L1 signaling indicating activation or deactivation of the configured uplink grant is stored or cleared as a configured uplink grant. Type 1 and Type 2 are configured by the RRC for each serving cell and each BWP. Multiple configurations are only active simultaneously on different serving cells. For Type 2, activation and deactivation between serving cells are independent. For the same serving cell, the MAC entity is configured as either Type 1 or Type 2.

[0119] When the configured authorization type 1 is configured, the UE is provided with at least the following parameters via RRC signaling from the BS: - cs-RNTI, which is CS-RNTI for retransmission; - Periodicity, which provides periodicity for configured license type 1; - timeDomainOffset, which represents the offset of the resource in the time domain relative to SFN=0; - The timeDomainAllocation value m provides a row index m+1 pointing to the allocation table, indicating the combination of the start symbol S, length L, and PUSCH mapping type; - frequencyDomainAllocation, which provides frequency domain resource allocation; and - mcsAndTBS, which provides IMCS representing modulation order, target code rate, and transport block size. When configured with a configured grant type 1 for the serving cell by the RRC, the UE stores the uplink grant provided by the RRC as a configured uplink grant for the indicated serving cell, and initializes or reinitializes the configured uplink grant to start in the symbol according to timeDomainOffset and S (derived from SLIV), and reappears periodically. After configuring the uplink grant for configured grant type 1, the UE considers the uplink grant to be associated with each symbol, where: [(SFN [numberOfSlotsPerFrame (numberOfSymbolsPerSlot) + (Number of slots in the frame × numberOfSymbolsPerSlot) + Number of symbols in the slot] = (timeDomainOffset) numberOfSymbolsPerSlot + S + N (Periodic) modulo (1024) numberOfSlotsPerFrame (numberOfSymbolsPerSlot), for all N >= 0.

[0120] When the configured authorization type 2 is configured, at least the following parameters are provided to the UE via RRC signaling from the BS: - cs-RNTI, which is CS-RNTI for activation, deactivation, and retransmission; and - Periodicity, which provides periodicity for configured license type 2. The actual uplink license is provided to the UE via PDCCH (addressed to CS-RNTI). After configuring uplink license for configured license type 2, the UE considers the uplink license to be associated with each symbol, where: [(SFN numberOfSlotsPerFrame (numberOfSymbolsPerSlot) + (number of time slots in the frame) [numberOfSymbolsPerSlot + Number of symbols in the slot] = [(SFN)] start time numberOfSlotsPerFrame numberOfSymbolsPerSlot + slot start time numberOfSymbolsPerSlot +symbol start time )+ N [Periodic] modulo(1024 × numberOfSlotsPerFrame) (numberOfSymbolsPerSlot), for all N >= 0, where SFN start time slot start time and symbol start timeThese are the SFN, slot, and symbol of the first transmission opportunity of the PUSCH where the configured uplink grant is (re)initialized. `numberOfSlotsPerFrame` and `numberOfSymbolsPerSlot` refer to the number of consecutive slots per frame and the number of consecutive OFDM symbols per slot, respectively.

[0121] For configured uplink grants, the HARQ process ID associated with the first symbol of the UL transmission is derived from the following equation: HARQ process ID = [floor(CURRENT_symbol / periodicity)] modulo nrofHARQ-Processes Where CURRENT_symbol = (SFN × numberOfSlotsPerFrame × numberOfSymbolsPerSlot + number of slots in the frame × numberOfSymbolsPerSlot + number of symbols in the slots), and numberOfSlotsPerFrame and numberOfSymbolsPerSlot refer to the number of consecutive slots per frame and the number of consecutive symbols per slot as specified in TS 38.211, respectively. CURRENT_symbol refers to the symbol index of the first transmission at which duplicate binding occurs. If the configured uplink grant is activated and the associated HARQ process ID is less than nrofHARQ-Processes, then a HARQ process is configured for the configured uplink grant.

[0122] For the downlink, the UE can configure semi-persistent scheduling (SPS) for each serving cell and each BWP via RRC signaling from the BS. Multiple configurations can only be active simultaneously on different serving cells. Activation and deactivation of DL SPS are independent between serving cells. For DL ​​SPS, DL assignment is provided to the UE via PDCCH and stored or cleared based on L1 signaling indicating SPS activation or deactivation. When configuring SPS, the following parameters are provided to the UE via RRC signaling from the BS: - cs-RNTI, which is CS-RNTI for activation, deactivation and retransmission; - nrofHARQ-Processes: This provides the number of HARQ processes configured for SPS; - Periodicity, which provides periodicity for downlink assignment for SPS configuration.

[0123] When the SPS is released by the upper layer, all corresponding configurations should be released as well.

[0124] After configuring downlink assignment for SPS, the UE considers the Nth downlink assignment to occur in the following time slots: (numberOfSlotsPerFrame) SFN + Number of slots in a frame = [(numberOfSlotsPerFrame)] SFN start time + slot start time ) + N Periodic numberOfSlotsPerFrame / 10]modulo(1024 (numberOfSlotsPerFrame), where SFN start time and slot start time These are the SFN and time slot of the first transmission of the (re)initialized PDSCH, which is configured for downlink assignment.

[0125] For the configured downlink assignment, the HARQ process ID associated with the time slot where the DL transmission begins is derived from the following equation: HARQ process ID = [floor (CURRENT_slot × 10 / (numberOfSlotsPerFrame × periodicity))] modulo nrofHARQ-Processes Wherein, CURRENT_slot = [(SFN × numberOfSlotsPerFrame) + number of slots in the frame], and numberOfSlotsPerFrame refers to the number of consecutive slots per frame as specified in TS 38.211.

[0126] If the Cyclic Redundancy Check (CRC) for the corresponding DCI format is scrambled by the CS-RNTI provided by the RRC parameter cs-RNTI and the New Data Indicator field for the enabled transport block is set to 0, the UE verifies the DL SPS assigned PDCCH or the configured UL license type 2 PDCCH for schedule activation or schedule release. Verification of the DCI format is implemented if all fields for the DCI format are set according to Table 4 or Table 5. Table 4 shows the specific fields for PDCCH verification for DL ​​SPS and UL license type 2 schedule activation, and Table 5 shows the specific fields for PDCCH verification for DL ​​SPS and UL license type 2 schedule release.

[0127] [Table 4]

[0128] [Table 5]

[0129] The actual DL assignment and actual UL grant, along with the corresponding modulation and coding scheme, are provided by the resource assignment fields (e.g., time-domain resource assignment fields providing the time-domain resource assignment value m, frequency-domain resource assignment fields providing frequency resource block allocation, and modulation and coding scheme fields) in the DCI format carried by the DL SPS and UL grant type 2 scheduling activation PDCCH. If authentication is implemented, the UE treats the information in the DCI format as a valid activation or release of the DL SPS or the configured UL grant type 2.

[0130] Regarding UL, the processor 102 of this disclosure can transmit (or control transceiver 106 to transmit) the data units of this disclosure based on the UL authorization available to the UE. The processor 202 of this disclosure can receive (or control transceiver 206 to receive) the data units of this disclosure based on the UL authorization available to the UE.

[0131] For DL, the processor 102 of this disclosure can receive (or control the transceiver 106 to receive) the DL data of this disclosure based on the DL assignment available to the UE. The processor 202 of this disclosure can send (or control the transceiver 206 to send) the DL data of this disclosure based on the DL assignment available to the UE.

[0132] The data units of this disclosure are processed by the physical layer at the transmitting side before being transmitted via the radio interface, and the radio signals carrying the data units of this disclosure are processed by the physical layer at the receiving side. For example, a MAC PDU including a PDCP PDU according to this disclosure can be processed by the physical layer as follows.

[0133] Figure 7 An example of physical layer processing at the transmitting side is shown.

[0134] The following tables show the mapping of transport channels (TrCH) and control information to their corresponding physical channels. Specifically, Table 6 specifies the mapping of uplink transport channels to their corresponding physical channels, Table 7 specifies the mapping of uplink control channel information to their corresponding physical channels, Table 8 specifies the mapping of downlink transport channels to their corresponding physical channels, and Table 9 specifies the mapping of downlink control channel information to their corresponding physical channels.

[0135] [Table 6]

[0136] [Table 7]

[0137] [Table 8]

[0138] [Table 9]

[0139] <encoding>

[0140] Data and control flows from / to the MAC layer are encoded to provide transmission and control services via the radio transmission link in the PHY layer. For example, transport blocks from the MAC layer are encoded into codewords at the transmitting side. The channel coding scheme is a combination of error detection, error correction, rate matching, interleaving, and mapping to / from the physical channel of transport channel or control information.

[0141] In the 3GPP NR system, the following channel coding schemes are used for different types of TrCH and different control information types.

[0142] [Table 10]

[0143] [Table 11]

[0144] For transmissions of DL transport blocks (i.e., DL MAC PDUs) or UL transport blocks (i.e., UL MAC PDUs), a transport block CRC sequence is appended to provide error detection for the receiving side. In 3GPP NR systems, communication devices use low-density parity-check (LDPC) codes when encoding / decoding UL-SCH and DL-SCH. 3GPP NR systems support two LDPC base maps (i.e., two LDPC base matrices): an LDPC base optimized for small transport blocks. Figure 1 and LDPC base optimized for larger transport blocks Figure 2 The LDPC base is selected based on the transport block size and code rate R. Figure 1 or LDPC base Figure 2 The code rate R is indicated by the Modulation and Coding Scheme (MCS) index IMCS. The MCS index is dynamically provided to the UE via the PDCCH that schedules the PUSCH or PDSCH, via the PDCCH that activates or (re)initializes the UL-configured license 2 or DL ​​SPS, or via RRC signaling associated with UL-configured license type 1. If the CRC-attached transport block is larger than the maximum block size for the selected LDPC base map, the CRC-attached transport block can be segmented into blocks, and an additional CRC sequence is attached to each block. For the LDPC base map... Figure 1 and LDPC basis Figure 2The maximum block sizes are 8448 bits and 3480 bits, respectively. If the CRC-attached transport block is no larger than the maximum block size of the selected LDPC base map, the CRC-attached transport block is encoded using the selected LDPC base map. Each block of the transport block is encoded using the selected LDPC base map. The LDPC-encoded blocks are then rate-matched individually. Block concatenation is performed to create codewords for transmission on PDSCH or PUSCH. For PDSCH, a maximum of two codewords (i.e., a maximum of two transport blocks) can be transmitted simultaneously on PDSCH. PUSCH can be used for the transmission of UL-SCH data and Layer 1 / 2 control information. Although in Figure 8 Although not shown in the diagram, the layer 1 / 2 control information can be multiplexed with the codewords for UL-SCH data.

[0145] <Scrambling and Modulation>

[0146] The bits of the codeword are scrambled and modulated to generate blocks of complex-valued modulated symbols.

[0147] <Layer Mapping>

[0148] The complex-valued modulation symbols of a codeword are mapped to one or more Multiple-Input Multiple-Output (MIMO) layers. A codeword can be mapped to a maximum of four layers. A PDSCH can carry two codewords, and therefore can support up to eight layers of transmission. A PUSCH supports a single codeword, and therefore can support up to four layers of transmission.

[0149] <Transform Precoding>

[0150] The DL transmission waveform is a regular OFDM using a cyclic prefix (CP). For DL, no transform precoding (in other words, Discrete Fourier Transform (DFT)) is applied.

[0151] The UL transmission waveform is regular OFDM using CP, where transform precoding, which performs DFT extension, can be disabled or enabled. In 3GPP NR systems, transform precoding can be selectively applied to UL waveforms if enabled. Transform precoding extends the UL data in a special way to reduce the peak-to-average power ratio (PAPR) of the waveform. Transform precoding is a form of DFT. In other words, 3GPP NR systems support two options for UL waveforms: CP-OFDM (the same as DL waveforms) and DFT-s-OFDM. Whether the UE must use CP-OFDM or DFT-s-OFDM is configured by the BS via RRC parameters.

[0152] Subcarrier mapping

[0153] Layers are mapped to antenna ports. In DL, for the mapping from layers to antenna ports, transparent (non-codebook-based) mapping is supported, and how beamforming or MIMO precoding is performed is transparent to the UE. In UL, for the mapping from layers to antenna ports, both non-codebook-based mapping and codebook-based mapping are supported.

[0154] For each antenna port (i.e., layer) used for the transmission of a physical channel (e.g., PDSCH, PUSCH), complex-valued modulation symbols are mapped to subcarriers in the resource blocks allocated to the physical channel.

[0155] <OFDM modulation>

[0156] The communication device at the transmitting side generates a time-continuous OFDM baseband signal on the subcarrier spacing configuration u and antenna port p for OFDM symbol l in the TTI for the physical channel by adding a cyclic prefix (CP) and performing IFFT. For example, for each OFDM symbol, the communication device at the transmitting side can perform an inverse fast Fourier transform (IFFT) on the complex-valued modulation symbols mapped to the resource blocks in the corresponding OFDM symbol and add a CP to the IFFT'ed signal to generate an OFDM baseband signal.

[0157] <Up-conversion>

[0158] The communication device at the transmitting side up-converts the OFDM baseband signal for antenna port p, subcarrier spacing configuration u, and OFDM symbol l to the carrier frequency f0 of the cell to which the physical channel is assigned.

[0159] Figure 2 The processors 102 and 202 in can be configured to perform encoding, scrambling, modulation, layer mapping, transform precoding (for UL), subcarrier mapping, and OFDM modulation. The processors 102 and 202 can control the transceivers 106 and 206 connected to the processors 102 and 202 to up-convert the OFDM baseband signal to the carrier frequency to generate a radio frequency (RF) signal. The RF signal is transmitted to an external device through antennas 108 and 208.

[0160] Figure 8 An example of physical layer processing at the receiving side is illustrated.

[0161] The physical layer processing at the receiving side is basically the inverse processing of the physical layer processing at the transmitting side.

[0162] <Frequency down-conversion>

[0163] The communication device at the receiving side receives an RF signal at the carrier frequency through an antenna. The transceivers 106 and 206 that receive the RF signal at the carrier frequency down-convert the carrier frequency of the RF signal to the baseband to obtain an OFDM baseband signal.

[0164] <OFDM Demodulation>

[0165] At the receiving side, the communication device obtains complex-valued modulation symbols via CP separation and FFT. For example, for each OFDM symbol, the communication device at the receiving side removes the CP from the OFDM baseband signal and performs FFT on the OFDM baseband signal with the CP removed to obtain complex-valued modulation symbols for antenna port p, subcarrier spacing u, and OFDM symbol l.

[0166] <Subcarrier Demapping>

[0167] Subcarrier demapping is performed on the complex-valued modulation symbols to obtain complex-valued modulation symbols of the corresponding physical channel. For example, processor 102 can obtain the complex-valued modulation symbols mapped to the subcarriers belonging to PDSCH from among the complex-valued modulation symbols received in the bandwidth part. For another example, processor 202 can obtain the complex-valued modulation symbols mapped to the subcarriers belonging to PUSCH from among the complex-valued modulation symbols received in the bandwidth part.

[0168] <Transform Demaprecoding>

[0169] If transform precoding has been enabled for the uplink physical channel, transform demaprecoding (e.g., IDFT) is performed on the complex-valued modulation symbols of the uplink physical channel. For the downlink physical channel and the uplink physical channel with transform precoding disabled, transform demaprecoding is not performed.

[0170] <Layer Demapping>

[0171] The complex-valued modulation symbols are demapped into one or two codewords.

[0172] <Demodulation and Descrambling>

[0173] The complex-valued modulation symbols of the codeword are demodulated and descrambling into bits of the codeword.

[0174] <Decoding>

[0175] The codeword is decoded into a transport block. For UL-SCH and DL-SCH, the LDPC base is selected according to the size of the transport block and the code rate R Figure 1 or LDPC base Figure 2A codeword may include one or more coded blocks. Each coded block is decoded using the selected LDPC base graph into either a CRC-attached code block or a CRC-attached transport block. If code block segmentation is performed on the CRC-attached transport block at the transmitting side, the CRC sequence is removed from each of the CRC-attached code blocks to obtain the code block. The code blocks are concatenated into a CRC-attached transport block. The transport block CRC sequence is removed from the CRC-attached transport block to obtain the transport block. The transport block is then passed to the MAC layer.

[0176] In the physical layer processing at the transmitting and receiving sides described above, the time-domain and frequency-domain resources (e.g., OFDM symbols, subcarriers, carrier frequencies) related to subcarrier mapping, OFDM modulation, and frequency up-conversion / down-conversion can be determined based on resource allocation (e.g., UL licensing, DL assignment).

[0177] For uplink data transmission, the processor 102 of this disclosure can apply (or control transceiver 106 to) the aforementioned physical layer processing on the transmitting side to the data unit of this disclosure to wirelessly transmit the data unit. For downlink data reception, the processor 102 of this disclosure can apply (or control transceiver 106 to) the aforementioned physical layer processing on the receiving side to the received radio signal to obtain the data unit of this disclosure.

[0178] For downlink data transmission, the processor 202 of this disclosure can apply (or control transceiver 206 to) the aforementioned physical layer processing on the transmitting side to the data unit of this disclosure to wirelessly transmit the data unit. For uplink data reception, the processor 202 of this disclosure can apply (or control transceiver 206 to) the aforementioned physical layer processing on the receiving side to the received radio signal to obtain the data unit of this disclosure.

[0179] <Retransmission based on discard indication>

[0180] According to 3GPP standard (TS38.322) version 17 of the RLC layer, when an RLC PDU including an RLC SDU is submitted to the lower layer, the RLC entity can include polling bits in the RLC PDU to request a status report from the peer RLC entity and start a polling retransmission timer.

[0181] Even if the RLC SDU submitted to the lower layer is indicated by a drop instruction from the PDCP, the RLC SDU will not be dropped, and the RLC entity will continue to transmit the RLC SDU until it receives a status report from the peer RLC entity containing information related to the RLC SDU or a radio link failure occurs (i.e., the maximum retransmission limit for the RLC SDU is reached). If the polling retransmission timer expires, the RLC entity includes polling in the RLC PDU according to the polling procedure. In this case, if both the new transmission buffer and the retransmission buffer are empty or the transmission window is stalled (i.e., there is no new transmission in the transmission window), the RLC entity selects the RLC SDU with the highest sequence number in the transmission window or any RLC SDU that has not yet been definitively acknowledged for retransmission.

[0182] However, in 3GPP standard release 18 regarding XR technology, when the discard timer for one PDU in a PDU set expires, PDU set-based discarding is introduced to discard all associated PDUs in the PDU set. Since the discard timer value for low-importance PDUs is smaller than that for higher-importance PDUs, PSI-based discarding enhancement is also introduced to discard low-importance PDUs earlier than high-importance PDUs.

[0183] The problem with this behavior is that when the polling retransmission timer expires and the transmission window stalls or both transmission buffers are empty, if the RLC entity selects the RLC SDU with the highest sequence number in the transmission window, or any RLCSDU that has not yet been definitively acknowledged for retransmission, without considering the remaining time of the RLC SDU and / or the drop indication from the PDCP, then RLC SDUs with remaining time below a threshold may not be retransmitted quickly, or RLC SDUs already indicated for drop by the PDCP may be unnecessarily retransmitted. This will lead to unnecessary data drop in either PDU set-based or PSI-based drop procedures, and the XR service quality will degrade.

[0184] Therefore, given the introduction of delay status reporting based on the remaining time of data in 3GPP standard release 18, it is critical to meet the delay requirements for each data (especially high-importance data), and the delay information / drop status of each data should be considered when the RLC entity selects an RLC SDU for retransmission.

[0185] According to this disclosure, when the polling retransmission timer expires, if both the transmission buffer and the retransmission buffer are empty or no new data (or no new data segments) can be sent, the UE should consider submitting data with the highest sequence number for retransmission to the lower layer, or any data that has not yet been confirmed for retransmission. The UE then includes polling the selected data for retransmission.

[0186] Specifically, for retransmissions, data indicated by discard instructions from the upper layer is not taken into account.

[0187] Alternatively, for retransmission, the highest sequence number among the data with remaining time below a threshold is considered, or the data with the minimum remaining time is considered, or the data with remaining time below a threshold is considered.

[0188] The UE has multiple layers (e.g., PDCP, RLC, and MAC layers), and each layer has its own function. In the following text, PDCP, RLC, and MAC layers are used to explain the layer concept, but are not limited to PDCP, RLC, and MAC layers, and the naming of each layer can be changed.

[0189] The PDCP entity can be configured with a delay threshold to determine delay-critical PDCP SDUs (i.e., PDCP SDUs with remaining time less than a delay threshold). When a PDCP SDU becomes a delay-critical PDCP SDU, the PDCP entity provides a delay-critical indication for the PDCP PDU to the lower layer. When the PDCP entity is configured for PDS-based discarding, if the discard timer for a PDCP SDU expires, the PDCP entity discards all PDCP SDUs belonging to the PDU set. Otherwise, when the PDCP entity is not configured for PDS-based discarding, if the discard timer for a PDCP SDU expires, the PDCP entity discards the PDCPSDU and the corresponding PDCP PDU.

[0190] When a PDCP entity is configured with a drop timer value for low-importance PDCP SDUs and PSI-based (i.e., PDU set importance) drop is activated, the PDCP entity starts a drop timer with a value specific to the low-importance PDCP SDU when it receives one. However, it starts a drop timer with a value not specific to the low-importance PDCP SDU when it receives a PDCP SDU other than a low-importance one (i.e., a high-importance PDCP SDU or a normal PDCP SDU). If PSI-based drop is not activated, one drop timer value is used for all PDCP SDUs. Low-importance PDCP SDUs can belong to a low-importance PDU set, and high-importance PDCP SDUs can belong to a high-importance PDU set.

[0191] An RLC entity can be configured with a sequence number (SN), at least one polling retransmission timer value, at least one polling PDU threshold, and at least one polling byte threshold. If the RLC transmit window size can be determined by subtracting one from the SN (e.g., if a 5-bit SN is configured), then the RLC transmit window size can be 16.

[0192] When the RLC entity receives an RLC SDU from the upper layer, it associates the received RLC SDU with the SN and may store those RLC SDUs in a transmission buffer for the new transmission. After the UE receives the uplink grant, the lower layer indicates to the RLC entity the total size of the RLC PDUs at a specific transmission opportunity. The RLC entity submits at least one RLC PDU, including either an RLC SDU or segments of an RLC SDU, up to the indicated total size, and those submitted RLC SDUs may be within the transmission window. The UE or the lower layer generates a MAC PDU including at least one RLC PDU and then transmits the MAC PDU using the uplink grant.

[0193] The RLC entity counts the number of RLC PDUs and the number of bytes of upper-layer data submitted to the lower layer.

[0194] An RLC entity includes polling bits in its RLC PDU when any of the following conditions 1) through 4) are met: 1) The number of counts submitted to the lower-level RLC PDUs is equal to or greater than at least one polling PDU threshold; 2) The number of bytes of upper-layer data submitted to the lower layer is equal to or greater than at least one polling byte threshold; 3) After the transmission of the submitted RLC PDU, both the transmission buffer and the retransmission buffer become empty. 4) No new RLC SDU can be sent after the transmission of the submitted RLC PDU.

[0195] When polling bits are included in at least one RLC PDU, both the counters for the number of RLC PDUs and the counters for the number of bytes of upper-layer data are set to zero. The RLC entity stores or updates the specific polling SN parameter of the RLC PDU with the highest SN among all RLC PDUs submitted to the lower layer as the RLC PDU including the polling bits is submitted, and then starts a polling retransmission timer with the configured value.

[0196] When an RLC entity receives a status report, it knows whether the submitted RLC SDU was successfully transmitted. If at least one submitted RLC SDU or RLC SDU segment is negatively acknowledged by the status report, the RLC entity considers the RLC SDU or RLC SDU segment with a negative indication for retransmission and can then store the RLC SDU or RLC SDU segment in the retransmission buffer for retransmission. When the RLC entity retransmits an RLC SDU, it increments the retransmission counter associated with the RLC SDU. When the first retransmission of an RLC SDU is performed, the retransmission counter is set to zero. When the retransmission counter reaches a specific value configured by the upper layer, the RLC entity can indicate a radio link problem (i.e., an RLC failure) to the upper layer.

[0197] When the polling retransmission timer expires, the RLC entity includes polling bits in the submitted RLC PDU. If both the transmit buffer and the retransmission buffer are empty and / or no new RLC SDU or RLC SDU segments can be sent, the RLC entity selects one of the RLC SDUs in the transmit window for retransmission.

[0198] When selecting an RLC SDU for retransmission, the RLC entity considers submitting the RLC SDU with the highest SN among the lower-level RLC SDUs or any RLC SDU for retransmission that has not yet been confirmed.

[0199] Specifically, the RLC entity also considers one or more of the following conditions i) to vii) to select the RLC SDU for retransmission: i) Since the RLC SDU has not yet been indicated by a discard instruction from the upper layer (i.e., if the RLC SDU is indicated by a discard instruction from the upper layer, the RLC entity may not select the RLC SDU indicated by the discard instruction); and / or ii) The RLC SDU has a remaining time equal to or less than a latency threshold that can be configured in the RLC or PDCP; and / or iii) The RLC SDU is indicated by a delay key indication from the upper layer (i.e., the RLCSDU associated with the delay key PDCP SDU); and / or iv) The RLC SDU has a minimum remaining time in the transmission window; and / or v) RLC SDUs are associated with high-importance PDCP SDUs or high-importance PDU sets (i.e., not with low-importance PDCP SDUs or low-importance PDU sets); and / or vi) RLC SDU associated with the PDCP control PDU; and / or vii) The RLC SDU has the highest maximum retransmission counter value among the RLC SDUs submitted to the lower layer (i.e., the RLC SDUs in the transmission window).

[0200] Alternatively, when no new RLC SDU or RLC SDU segment can be sent, the RLC entity may discard at least one RLC SDU indicated by a discard instruction from the upper layer, and then submit / send a new RLC SDU or RLC SDU segment.

[0201] Alternatively, when no new RLC SDU or RLC SDU segment can be sent, the RLC entity may discard at least one RLCSDU associated with a low-importance PDCP SDU or low-importance PDU set among the RLC SDUs submitted to the lower level, and then submit / send a new RLC SDU or RLC SDU segment associated with a high-importance PDCP SDU or high-importance PDU set. The RLC entity may report information about RLC SDUs discarded in the sending window (i.e., RLC SDU information removed from the sending window) to the peer RLC entity.

[0202] After receiving the uplink grant, the UE or lower layer generates a MAC PDU that includes the selected RLC SDU with polling bits for retransmission, and then uses the uplink grant to send the MAC PDU.

[0203] When the network receives an RLC PDU with polling bits, the network generates a status report that includes the reception information of the RLC SDU up to the SN of the next unreceived RLC SDU that has not been reported as lost, and then sends the status report to the UE.

[0204] Figure 9 A first example of performing a retransmission according to this disclosure is shown.

[0205] exist Figure 9 In this scenario, the sequence number is assumed to be 4 bits, and the transmission window size is 8. RLC SDUs with SN 1, SN 2, SN 3, and SN 5 have been positively acknowledged. The peer RLC entity successfully receives RLCSDUs with SN 1, SN 2, SN 3, and SN 5. It is also assumed that an RLC SDU with SN 4 is associated with a low-importance PDCP SDU, and that RLC SDUs with SN 6, SN 7, and SN 8 are associated with a high-importance PDCP SDU. The configured latency threshold is 5 ms.

[0206] At T1, after receiving the uplink clearance, the RLC entity submits an RLC SDU with SN 6, SN 7, and SN 8 to the MAC layer, and includes polling bits in the RLC PDU with RLC SDU 8, then starts a polling retransmission timer. However, the MAC PDU including the RLC SDU with SN 6, SN 7, and SN 8 is not successfully transmitted, and the peer receiving RLC entity does not receive the MAC PDU.

[0207] At T2, the polling retransmission timer expires and the transmission window stalls (i.e., no new RLC SDU or RLC SDU segment can be transmitted). The remaining times for RLC SDUs with SN 4, SN 6, SN 7, and SN 8 are 3ms, 4ms, 5ms, and 9ms, respectively.

[0208] At T3, after receiving the uplink permission, even though the RLC SDU with SN4 has a minimum remaining time of 3ms, the RLC entity selects the RLC SDU with SN6 for retransmission because the RLC SDU has not been affirmatively acknowledged, it is not associated with the low-importance PDCP SDU, and the remaining time of the RLC SDU with SN6 is below the delay threshold and is also the minimum remaining time among the RLC SDUs submitted to the lower layer.

[0209] The RLC entity submits an RLC SDU with SN 6 for retransmission to the MAC layer, and includes polling bits in the RLC PDU including the RLCSDU with SN 6, and then starts the polling retransmission timer.

[0210] Figure 10 A second example of performing retransmission according to this disclosure is shown.

[0211] exist Figure 10 In this scenario, the sequence number is assumed to be 4 bits, and the transmission window size is 8. RLC SDUs with SN 1, SN 2, SN 3, and SN 5 have been positively acknowledged. The peer RLC entity successfully receives RLCSDUs with SN 1, SN 2, SN 3, and SN 5. It is also assumed that an RLC SDU with SN 4 is associated with a low-importance PDCP SDU, and RLC SDUs with SN 6, SN 7, and SN 8 are associated with a high-importance PDCP SDU. The configured latency threshold is 5 ms.

[0212] At T1, after receiving the uplink clearance, the RLC entity submits an RLC SDU with SN 6, SN 7, and SN 8 to the MAC layer, and includes polling bits in the RLC PDU that includes the RLC SDU with SN 8, then starts a polling retransmission timer. However, the MAC PDU that includes the RLC SDU with SN 6, SN 7, and SN 8 is not successfully transmitted, and the peer receiving RLC entity does not receive the MAC PDU.

[0213] At T2, the polling retransmission timer expires and the transmission window stalls (i.e., no new RLC SDU or RLC SDU segment can be transmitted). The remaining times for RLC SDUs with SN 4, SN 6, SN 7, and SN 8 are 3ms, 4ms, 5ms, and 9ms, respectively.

[0214] At T3, after receiving the uplink clearance, the RLC entity removes the RLCSDU with SN 4 from the transmission window because the transmission window is paused and this RLC SDU is associated with a low-importance PDCP SDU. The RLC entity then submits an RLC SDU with SN 9 for the new transmission to the MAC layer, including polling bits in the RLC PDU that includes the RLC SDU with SN 9, and then starts a polling retransmission timer.

[0215] Figure 11 A third example of performing retransmission according to this disclosure is shown.

[0216] exist Figure 11 In this scenario, the sequence number is assumed to be 4 bits, and the transmission window size is 8. The RLCSDU with SN 1 and SN 5 has been affirmatively acknowledged. The peer RLC entity has successfully received the RLC SDU with SN 1 and SN 5.

[0217] At T1, after receiving the uplink grant, the RLC entity submits an RLC SDU with SN 6, SN 7 and SN 8 to the MAC layer, and includes polling bits in the RLC PDU with RLC SDU having SN 8, and then starts the polling retransmission timer.

[0218] However, the MAC PDU including the RLC SDU with SN 6, SN 7, and SN 8 was not successfully transmitted, and the peer receiving RLC entity did not receive the MAC PDU. When the RLC entity submitted the RLC SDU with SN 7 and SN 8, these two RLC SDUs were not indicated by a drop instruction from the upper layer.

[0219] At T2, the polling retransmission timer expires and the transmission window stalls (i.e., no new RLC SDUs or RLC SDUs can be transmitted). RLC SDUs with SN 7 and SN 8 are indicated by a drop instruction from the upper layer.

[0220] At T3, after receiving the uplink clearance, the RLC entity selects an RLC SDU with SN 6 for retransmission because this RLC SDU has not yet been affirmatively acknowledged and has not been discarded by a drop instruction from the upper layer. The RLC entity submits the RLC SDU with SN 6 for retransmission to the MAC layer, includes polling bits in the RLC PDU that includes the RLC SDU with SN 6, and then restarts the polling retransmission timer.

[0221] Figure 12 A flowchart is shown for performing the operations according to this disclosure.

[0222] Reference Figure 12 At A01, the UE's RLC entity submits one or more RLC Service Data Units (SDUs) to the UE's MAC entity. Preferably, when one or more RLC SDUs are submitted together with a polling query, a polling retransmission timer is started.

[0223] Next, at A02, the RLC entity receives a discard instruction from the UE’s Packet Data Convergence Protocol (PDCP) entity for at least one of the submitted RLC SDUs.

[0224] If the polling retransmission timer expires, the RLC entity selects the RLC SDU for retransmission from one or more submitted RLC SDUs, in addition to at least one RLC SDU indicated by the discard instruction at A03.

[0225] Preferably, the RLC entity is never selected from one or more submitted RLC SDUs that have been indicated by a drop instruction and have not yet been confirmed as the RLC SDU for retransmission.

[0226] Alternatively, the RLC entity may select from one or more submitted RLC SDUs, other than the one RLC SDU indicated by the drop instruction, until the RLC SDU with the minimum remaining retransmission time is dropped.

[0227] Alternatively, the RLC entity selects the RLC SDU indicated by the delay key indication for retransmission from one or more submitted RLC SDUs, other than the one RLC SDU indicated by the drop indication.

[0228] Of course, as with existing technologies, if both the transmission buffer and the retransmission buffer are empty, or if no new RLC SDU or RLC SDU segment can be sent due to a window pause, then a process for selecting the RLC SDU for retransmission is performed.

[0229] Finally, at A04, the RLC entity submits the RLC SDU for retransmission selection to the MAC entity. Preferably, the RLC SDU for retransmission selection is submitted along with polling. Therefore, the polling retransmission timer is restarted when the RLC SDU for retransmission selection is submitted.

[0230] According to this disclosure, when the polling retransmission timer expires, the UE can select the RLC SDU for retransmission based on its remaining time or a discard indication received from the upper layer. Therefore, this prevents unnecessary retransmission of old data and allows for the timely transmission of urgent XR data to the network, improving the user experience of XR services. It also avoids wasting radio resources.

Claims

1. A method comprising the following steps: The Radio Link Control (RLC) entity of the User Equipment (UE) submits one or more RLC Service Data Units (SDUs) to the Medium Access Control (MAC) entity of the UE. The RLC SDUs are submitted together with polling based on the RLC SDUs in the one or more RLC SDUs, and a polling retransmission timer is started. The RLC entity receives a discard instruction from the UE's Packet Data Convergence Protocol (PDCP) entity for at least one of the submitted RLC SDUs; Upon the expiration of the polling retransmission timer, the RLC entity selects the RLC SDU for retransmission from one or more submitted RLC SDUs, excluding the at least one RLC SDU indicated by the discard indication; and The RLC entity submits the RLC SDU for retransmission selection to the MAC entity.

2. The method according to claim 1, wherein, The steps for selecting the RLC SDU for retransmission include: The RLC SDU to be retransmitted is selected from one or more submitted RLC SDUs that have never been indicated by the discard instruction and have not yet been confirmed.

3. The method according to claim 1, wherein, The RLC SDU for retransmission is selected based on the fact that both the transmission buffer and the retransmission buffer are empty, or based on the fact that no new RLC SDU or RLC SDU segment can be sent due to window pause.

4. The method according to claim 1, wherein, The steps for submitting the RLC SDU for retransmission selection include: The RLC SDU for retransmission selection is submitted together with the polling; and Restart the polling retransmission timer.

5. The method according to claim 1, wherein, The steps for selecting the RLC SDU for retransmission include: Select from the submitted one or more RLC SDUs, other than the at least one RLC SDU indicated by the discard instruction, until the RLC SDU with the minimum remaining time is discarded.

6. The method according to claim 1, wherein, The steps for selecting the RLC SDU for retransmission include: For retransmission, select the RLC SDU indicated by the delay key indication from the upper layer from one or more submitted RLC SDUs, other than the at least one RLC SDU indicated by the drop indication.

7. A user equipment (UE), the UE comprising: At least one processor; as well as At least one memory, wherein instructions are stored in the at least one memory, and the instructions, when executed by the at least one processor, cause the UE to perform at least the following operations: The Radio Link Control (RLC) entity of the UE submits one or more RLC Service Data Units (SDUs) to the Medium Access Control (MAC) entity of the UE, wherein the RLC SDUs are submitted together with polling based on the one or more RLC SDUs, and a polling retransmission timer is started. The RLC entity receives a discard instruction from the UE's Packet Data Convergence Protocol (PDCP) entity for at least one of the submitted RLC SDUs; Upon the expiration of the polling retransmission timer, the RLC entity selects the RLC SDU for retransmission from one or more submitted RLC SDUs, excluding the at least one RLC SDU indicated by the discard indication; and The RLC entity submits the RLC SDU for retransmission selection to the MAC entity.

8. The UE according to claim 7, wherein, The steps for selecting the RLC SDU for retransmission include: The RLC SDU to be retransmitted is selected from one or more submitted RLC SDUs that have never been indicated by the discard instruction and have not yet been confirmed.

9. The UE according to claim 7, wherein, The RLC SDU for retransmission is selected based on the fact that both the transmission buffer and the retransmission buffer are empty, or based on the fact that no new RLC SDU or RLC SDU segment can be sent due to window pause.

10. The UE according to claim 7, wherein, The steps for submitting the RLC SDU for retransmission selection include: The RLC SDU for retransmission selection is submitted together with the polling; and Restart the polling retransmission timer.

11. The UE according to claim 7, wherein, The steps for selecting the RLC SDU for retransmission include: Select from the submitted one or more RLC SDUs, other than the at least one RLC SDU indicated by the discard instruction, until the RLC SDU with the minimum remaining time is discarded.

12. The UE according to claim 7, wherein, The steps for selecting the RLC SDU for retransmission include: For retransmission, select the RLC SDU indicated by the delay key indication from the upper layer from one or more submitted RLC SDUs, other than the at least one RLC SDU indicated by the drop indication.

13. An apparatus for a user equipment (UE), the apparatus comprising: At least one processor; as well as At least one memory, wherein instructions are stored in the at least one memory, and the instructions, when executed by the at least one processor, cause the UE to perform at least the following operations: The Radio Link Control (RLC) entity of the UE submits one or more RLC Service Data Units (SDUs) to the Medium Access Control (MAC) entity of the UE, wherein the RLC SDUs are submitted together with polling based on the one or more RLC SDUs, and a polling retransmission timer is started. The RLC entity receives a discard instruction from the UE's Packet Data Convergence Protocol (PDCP) entity for at least one of the submitted RLC SDUs; Upon the expiration of the polling retransmission timer, the RLC entity selects the RLC SDU for retransmission from one or more submitted RLC SDUs, excluding the at least one RLC SDU indicated by the discard indication; and The RLC entity submits the RLC SDU for retransmission selection to the MAC entity.

14. A non-transitory computer-readable storage medium comprising program instructions that, when executed by a processor, cause a user equipment (UE) to perform at least the following operations: The Radio Link Control (RLC) entity of the UE submits one or more RLC Service Data Units (SDUs) to the Medium Access Control (MAC) entity of the UE, wherein, Based on the RLC SDU in one or more RLC SDUs, submit it together with the polling and start the polling retransmission timer; The RLC entity receives a discard instruction from the UE's Packet Data Convergence Protocol (PDCP) entity for at least one of the submitted RLC SDUs; Upon the expiration of the polling retransmission timer, the RLC entity selects the RLC SDU for retransmission from one or more submitted RLC SDUs, excluding the at least one RLC SDU indicated by the discard indication; as well as The RLC entity submits the RLC SDU for retransmission selection to the MAC entity.

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