Method and apparatus for data transmission and reception for network coordinated communications

Abstract

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method and apparatus for transmitting and receiving data for coordinated communication are provided.

Description

[0001] This application is a divisional application of an invention patent application with an application date of January 7, 2020, application number 202080008659.5, and invention name “Method and device for sending and receiving data for network coordinated communication”. Technical Field

[0002] The present disclosure relates to a wireless communication system and more particularly to a method and apparatus for transmitting and receiving data between a terminal and a plurality of transmission nodes that perform coordinated communication to smoothly provide services. Background Art

[0003] In order to meet the increased demand for wireless data services since the deployment of the fourth generation (4G) communication system, efforts have been made to develop improved fifth generation (5G) or pre-5G communication systems. Therefore, 5G or pre-5G communication systems are also called "super 4G networks" or "post-long term evolution (LTE) systems". 5G communication systems are considered to be implemented in higher frequency (mmWave) bands (e.g., 60GHz bands) in order to achieve higher data rates. In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple input multiple output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technologies are discussed in 5G communication systems. In addition, in 5G communication systems, system network improvements are being developed based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, cooperative communications, coordinated multipoints (CoMP), receiving-end interference cancellation, etc. In 5G systems, hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) (FQAM) and sliding window superposition coding (SWSC) as advanced coded modulation (ACM), and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies have been developed.

[0004] The Internet, which is a human-centered connected network in which humans generate and consume information, is now evolving toward the Internet of Things (IoT) in which distributed entities (such as things) exchange and process information without human intervention. The Internet of Everything (IoE) has emerged as a combination of IoT technology and big data processing technology through connection with cloud servers. As technical elements such as "sensing technology", "wired / wireless communication and network infrastructure", "service interface technology" and "security technology" are required for IoT implementation, sensor networks, machine-to-machine (M2M) communication, machine-type communication (MTC), etc. have recently been studied. This IoT environment can provide smart Internet technology services that create new value for human life by collecting and analyzing data generated between connected things. IoT can be applied to various fields including smart homes, smart buildings, smart cities, smart cars or connected cars, smart grids, healthcare, smart appliances and advanced medical services through the integration and combination of existing information technology (IT) with various industrial applications.

[0005] In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, machine type communications (MTC), and machine-to-machine (M2M) communications can be implemented through beamforming, MIMO, and array antennas. Cloud radio access networks (RANs) as an application of the above-mentioned big data processing technologies can also be considered as an example of the convergence between 5G technology and IoT technology.

[0006] As communication systems develop, a process of exchanging data between a plurality of nodes and terminals performing network coordinated communication is being actively studied.

[0007] The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with respect to the present disclosure. Summary of the invention

[0008] Technical issues

[0009] There is a need to enhance data transmission between a terminal and multiple transmission nodes that perform coordinated communications.

[0010] Solution to the problem

[0011] Various aspects of the present disclosure are to at least solve the above-mentioned problems and / or disadvantages and to provide at least the following advantages. Therefore, one aspect of the present disclosure is to provide a wireless communication system, and more specifically, to provide a method and apparatus for efficiently transmitting data between a terminal and a plurality of transmission nodes performing coordinated communication.

[0012] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments.

[0013] According to one aspect of the present disclosure, when network coordinated communication is used in a wireless communication system, the computational complexity and receiving hardware complexity of the terminal can be reduced. In addition, when network coordinated communication is used, the interference of different sending and receiving nodes to the terminal can be reduced, thereby effectively performing network coordinated communication.

[0014] According to an embodiment of the present disclosure, a method performed by a terminal includes: receiving first downlink control information (DCI) scheduling a first physical downlink shared channel (PDSCH) transmission from a first transmission and reception point (TRP); receiving a second DCI scheduling a second PDSCH transmission from a second TRP, wherein the second PDSCH transmission overlaps with the first PDSCH in time-frequency resources; and receiving the first PDSCH transmission and the second PDSCH transmission based on a first demodulation reference signal (DMRS) associated with the first PDSCH transmission and a second DMRS associated with the second PDSCH transmission, wherein the first DMRS and the second DMRS are received at the same position within the time-frequency resources.

[0015] According to an embodiment of the present disclosure, a method performed by a first transmit reception point (TRP) includes: sending first downlink control information (DCI) for scheduling a first physical downlink shared channel (PDSCH) transmission to a terminal; and sending the first PDSCH transmission to the terminal based on a demodulation reference signal (DMRS) associated with the first PDSCH transmission, wherein a second DCI for scheduling a second PDSCH transmission is sent from a second TRP to the terminal, wherein the second PDSCH transmission is sent to the terminal based on a second DMRS associated with the second PDSCH transmission, wherein the second PDSCH transmission overlaps with the first PDSCH transmission on time-frequency resources, and wherein the first DMRS and the second DMRS are sent at the same position within the time-frequency resources.

[0016] According to an embodiment of the present disclosure, a terminal includes: a transceiver configured to send and receive signals; and a controller configured to: receive first downlink control information (DCI) scheduling a first physical downlink shared channel (PDSCH) transmission from a first transmit receive point (TRP), receive second DCI scheduling a second PDSCH transmission from a second TRP, wherein the second PDSCH transmission overlaps with the first PDSCH in time-frequency resources, and receive the first PDSCH transmission and the second PDSCH transmission based on a first demodulation reference signal (DMRS) associated with the first PDSCH transmission and a second DMRS associated with the second PDSCH transmission, wherein the first DMRS and the second DMRS are received at the same position within the time-frequency resources.

[0017] According to an embodiment of the present disclosure, a first TRP includes: a transceiver configured to send and receive signals; and a controller configured to: send first downlink control information (DCI) scheduling a first physical downlink shared channel (PDSCH) transmission to a terminal, and send the first PDSCH transmission to the terminal based on a demodulation reference signal (DMRS) associated with the first PDSCH transmission, wherein a second DCI scheduling a second PDSCH transmission is sent from a second TRP to the terminal, wherein the second PDSCH transmission is sent to the terminal based on a second DMRS associated with the second PDSCH transmission, wherein the second PDSCH transmission overlaps with the first PDSCH transmission on time-frequency resources, and wherein the first DMRS and the second DMRS are sent at the same position within the time-frequency resources.

[0018] According to an embodiment of the present disclosure, a method performed by a terminal in a communication system includes: receiving first downlink control information DCI for scheduling a first physical downlink shared channel PDSCH from a first transmitting and receiving point TRP; receiving a second DCI for scheduling a second PDSCH from a second TRP; receiving a first PDSCH from the first TRP based on a first PDSCH demodulation reference signal DMRS for the first PDSCH; and receiving a second PDSCH from the second TRP based on a second PDSCH DMRS for the second PDSCH, wherein, in a case where the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH overlap in whole or in part in the time-frequency domain, wherein: the number of front-load DMRS symbols in the first DMRS configuration is the same as the number of front-load DMRS symbols in the second DMRS configuration; the number of additional DMRS symbols in the first DMRS configuration is the same as the number of additional DMRS symbols in the second DMRS configuration; the DMRS symbol position in the first DMRS configuration is the same as the DMRS symbol position in the second DMRS configuration; and the DMRS configuration type in the first DMRS configuration is the same as the DMRS configuration type in the second DMRS configuration.

[0019] According to an embodiment of the present disclosure, a method performed by a base station in a communication system includes: sending a first downlink control information DCI for scheduling a first physical downlink shared channel PDSCH to a terminal based on a first transmitting and receiving point TRP of the base station; and sending a second DCI for scheduling a second PDSCH to the terminal based on a second TRP of the base station; sending a first PDSCH and a first PDSCH demodulation reference signal DMRS for the first PDSCH to the terminal based on the first TRP; and sending a second PDSCH and a second PDSCH for the second PDSCH to the terminal based on the second TRP. DMRS, wherein, in a case where a first TRP and a second TRP are configured for multi-TRP-based data transmission, a first PDSCH and a second PDSCH overlap in whole or in part in the time-frequency domain, wherein: the number of frontload DMRS symbols in the first DMRS configuration is the same as the number of frontload DMRS symbols in the second DMRS configuration; the number of additional DMRS symbols in the first DMRS configuration is the same as the number of additional DMRS symbols in the second DMRS configuration; the DMRS symbol position in the first DMRS configuration is the same as the DMRS symbol position in the second DMRS configuration; and the DMRS configuration type in the first DMRS configuration is the same as the DMRS configuration type in the second DMRS configuration.

[0020] According to an embodiment of the present disclosure, a user equipment UE in a communication system includes: a transceiver; and a processor, coupled with the transceiver, and configured to: receive a first downlink control information DCI for scheduling a first physical downlink shared channel PDSCH from a first transmitting and receiving point TRP; receive a second DCI for scheduling a second PDSCH from a second TRP; based on a first PDSCH demodulation reference signal DMRS for the first PDSCH, receive a first PDSCH from the first TRP; and based on a second PDSCH demodulation reference signal DMRS for the second PDSCH, receive a first PDSCH from the first TRP; and receive a second DCI for scheduling a second PDSCH from the second PDSCH. DMRS, receiving a second PDSCH from a second TRP, wherein, when the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH overlap in whole or in part in the time-frequency domain, wherein: the number of frontload DMRS symbols in the first DMRS configuration is the same as the number of frontload DMRS symbols in the second DMRS configuration; the number of additional DMRS symbols in the first DMRS configuration is the same as the number of additional DMRS symbols in the second DMRS configuration; the DMRS symbol position in the first DMRS configuration is the same as the DMRS symbol position in the second DMRS configuration; and the DMRS configuration type in the first DMRS configuration is the same as the DMRS configuration type in the second DMRS configuration.

[0021] According to an embodiment of the present disclosure, a base station in a communication system includes: a transceiver; and a processor, coupled with the transceiver, and configured to: send a first downlink control information DCI for scheduling a first physical downlink shared channel PDSCH to a terminal based on a first transmitting and receiving point TRP of the base station; send a second DCI for scheduling a second PDSCH to the terminal based on a second TRP of the base station; send a first PDSCH and a first PDSCH demodulation reference signal DMRS for the first PDSCH to the terminal based on the first TRP; and send a second PDSCH and a second PDSCH for the second PDSCH to the terminal based on the second TRP. DMRS, wherein, in a case where a first TRP and a second TRP are configured for multi-TRP-based data transmission, a first PDSCH and a second PDSCH overlap in whole or in part in the time-frequency domain, wherein: the number of frontload DMRS symbols in the first DMRS configuration is the same as the number of frontload DMRS symbols in the second DMRS configuration; the number of additional DMRS symbols in the first DMRS configuration is the same as the number of additional DMRS symbols in the second DMRS configuration; the DMRS symbol position in the first DMRS configuration is the same as the DMRS symbol position in the second DMRS configuration; and the DMRS configuration type in the first DMRS configuration is the same as the DMRS configuration type in the second DMRS configuration.

[0022] Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure.

[0023] Disclosure of beneficial effects

[0024] According to various embodiments of the present disclosure, data transmission between a terminal and a plurality of transmission nodes performing coordinated communication may be effectively enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1 The transmission structure in the time-frequency domain of an LTE, LTE-A or NR system or a similar wireless communication system according to an embodiment of the present disclosure is shown;

[0027] Figure 2 The structure of frames, subframes and time slots in 5G according to an embodiment of the present disclosure is shown;

[0028] Figure 3 An example of the configuration of a bandwidth portion according to an embodiment of the present disclosure is shown;

[0029] Figure 4 An example of indicating and changing bandwidth portions according to an embodiment of the present disclosure is shown;

[0030] Figure 5 An example of a control region configuration of a downlink control channel according to an embodiment of the present disclosure is shown;

[0031] Figure 6 An example of frequency domain resource allocation of a physical downlink shared channel (PDSCH) according to an embodiment of the present disclosure is shown;

[0032] Figure 7 An example of time domain resource allocation of PDSCH according to an embodiment of the present disclosure is shown;

[0033] Figure 8 An example of time domain resource allocation of PDSCH according to an embodiment of the present disclosure is shown;

[0034] Fig. 9 The protocol stacks of a base station and a UE when executing a single cell, carrier aggregation, and dual connectivity according to an embodiment of the present disclosure are shown;

[0035] Fig.10 An example of coordinated communication antenna port configuration and resource allocation according to an embodiment of the present disclosure is shown;

[0036] Fig.11An example of configuration of downlink control information (DCI) for coordinating communications according to an embodiment of the present disclosure is shown;

[0037] Fig.12 The priority of PDSCH in NR and the priority of PDSCH according to an embodiment of the present disclosure are shown;

[0038] Fig.13 is a flow chart illustrating a method of prioritizing PDSCHs scheduled in overlapping time resources according to an embodiment of the present disclosure.

[0039] Fig.14 is a flowchart illustrating a method for a UE to activate a receiver for only one of non-coherent joint transmission (NC-JT) and multi-user multiple-input and multiple-output (MU-MIMO) in order to reduce complexity according to an embodiment of the present disclosure;

[0040] Fig.15 shows the structure of a terminal according to an embodiment of the present disclosure; and

[0041] Fig.16 The structure of a base station according to an embodiment of the present disclosure is shown.

[0042] The same reference numbers are used throughout the drawings to denote the same elements. DETAILED DESCRIPTION

[0043] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of the various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in understanding, but these are considered exemplary only. Therefore, it will be appreciated by those of ordinary skill in the art that various changes and modifications may be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, for clarity and brevity, descriptions of well-known functions and configurations may be omitted.

[0044] The terms and words used in the following description and claims are not limited to the written meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Therefore, it should be clear to those skilled in the art that the following description of various embodiments of the present disclosure is provided for illustrative purposes only and not for the purpose of limiting the present disclosure as defined by the attached claims and their equivalents.

[0045] It should be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0046] When describing the embodiments, descriptions of technologies known to those skilled in the art and not directly related to the present disclosure may be omitted. Such unnecessary omissions are intended to avoid confusing the subject matter of the present disclosure and to convey the subject matter more clearly.

[0047] Similarly, in the accompanying drawings, some elements may be exaggerated, omitted or schematically shown. In addition, the size of each element does not fully reflect the actual size. In the accompanying drawings, the same or corresponding elements have the same reference numerals.

[0048] By referring to the embodiments of the present disclosure described in detail below in conjunction with the accompanying drawings, the advantages and features of the present disclosure and their implementation methods will become apparent. The present disclosure is not limited to the embodiments disclosed below, but can be embodied in various forms. On the contrary, these embodiments are provided to make the present disclosure thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art to which the present disclosure belongs. The present disclosure is limited only by the scope of the claims. The same reference numerals always refer to the same elements.

[0049] Here, it will be understood that each box of the flowchart illustration and the combination of boxes in the flowchart illustration can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device create a tool for implementing the functions specified in the flowchart box or multiple boxes. These computer program instructions can also be stored in a non-temporary computer-usable or computer-readable memory, and the memory can instruct the computer or other programmable data processing device to operate in a specific manner so that the instructions stored in the non-temporary computer-usable or computer-readable memory produce a product including an instruction tool for implementing the functions specified in the flowchart box or multiple boxes. The computer program instructions can also be loaded onto a computer or other programmable data processing device to cause a series of operating steps to be performed on the computer or other programmable device to produce a computer-implemented process so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in the flowchart box or multiple boxes.

[0050] Furthermore, each block of the flowchart diagram may represent a module, segment, or portion of code, which includes one or more executable instructions for implementing (multiple) specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the blocks may not appear in order. For example, depending on the functions involved, two blocks shown in succession may actually be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order.

[0051] As used herein, "unit" refers to a software element or hardware element that performs a predetermined function, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). However, "unit" does not always have a meaning limited to software or hardware. "Unit" can be constructed to be stored in an addressable storage medium or to execute one or more processors. Therefore, "unit" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays, and parameters. The elements and functions provided by "units" can be combined into a smaller number of elements, "units" or divided into a larger number of elements, "units". In addition, elements and "units" can be implemented to reproduce one or more CPUs in a device or a secure multimedia card. In addition, according to some embodiments, "units" can include one or more processors.

[0052] Hereinafter, the operating principle of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description of the present disclosure, when it is determined that the detailed description may make the subject matter of the present disclosure unclear, the detailed description of the known configuration or function incorporated herein will be omitted. The terms described below are defined in consideration of the functions in the embodiments, and the meaning of the terms may vary according to the intention, convention, etc. of the user or operator. Therefore, the definition of the terms should be based on the content of the entire specification. Hereinafter, a base station is an entity that performs resource allocation for a terminal, and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a radio access unit, a base station controller, a transmit receive point (TRP), or a node in a network. The terminal may include a user equipment (UE), a mobile station, a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function, but is not limited thereto.

[0053] In the following, an embodiment illustrates a technology for a terminal to receive broadcast information from a base station in a wireless communication system. As used in the following description, terms referring to broadcast information, terms referring to control information, terms referring to communication coverage, terms referring to state changes (e.g., events), terms referring to network entities, terms referring to messages, terms referring to components of devices, etc. are shown for the purpose of description. Therefore, the present disclosure is not limited to the following terms, and other terms with equivalent technical meanings may be used.

[0054] For convenience of explanation, some terms and words defined in the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) standard may be used. However, the present disclosure is not limited by these terms and words and can be equally applied to systems according to other standards.

[0055] Wireless communication systems are evolving from initially providing voice-oriented services to broadband wireless communication systems for providing high-speed and high-quality packet data services according to communication standards, such as High Speed ​​Packet Access (HSPA), Long Term Evolution (LTE or Evolved Universal Terrestrial Radio Access (E-UTRA)), LTE-advanced (LTE-A) or LTE-Pro of 3GPP, High Speed ​​Packet Data (HRPD) or Ultra Mobile Broadband (UMB) of 3GPP2, and IEEE 802.16e.

[0056] As a representative example of a broadband wireless communication system, the LTE system adopts an orthogonal frequency division multiplexing (OFDM) scheme for the downlink (DL) and a single carrier frequency division multiple access (SC-FDMA) scheme for the uplink (UL). The uplink refers to a radio link used for a user equipment (UE) or a mobile station (MS) to send data or control signals to an eNode B or a base station (BS), while the downlink refers to a radio link used for an eNode B to send data or control signals to a UE. These multiple access schemes allocate and manage time-frequency resources used to carry data or control information for each user without overlapping, i.e., mutually orthogonal, thereby dividing the data or control information for each user.

[0057] The post-LTE communication system, namely the 5G communication system, needs to be able to freely reflect various demands from users and service providers, and is thus required to support services that meet various requirements. Services considered for the 5G communication system include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), ultra-reliable low latency communication (URLLC), etc.

[0058] According to some embodiments, eMBB is intended to provide a data rate that is further enhanced than the data rate supported by the existing LTE, LTE-A or LTE-Pro. For example, in a 5G communication system, for one base station, eMBB needs to be able to provide a peak data rate of 20 Gbps for the downlink and a peak data rate of 10 Gbps for the uplink. In addition, eMBB needs to provide an increased user-perceived data rate. In order to meet these requirements, improved transmission and reception techniques including enhanced multiple-input multiple-output (MIMO) transmission techniques are required. In addition, by adopting a frequency bandwidth wider than 20 MHz in a frequency band range of 3 GHz to 6 GHz or 6 GHz band or higher (rather than the 2-GHz band currently used for LTE), the data rate required by the 5G communication system can be met.

[0059] In the 5G communication system, mMTC is considered to support application services such as the Internet of Things (IoT). In order to effectively provide IoT, mMTC may require support for access to a large number of UEs in a cell, enhanced UE coverage, increased battery time, reduced UE costs, etc. IoT is attached to various sensors and various devices to provide communication functions, so it is necessary to be able to support a large number of UEs in a cell (for example, 1,000,000 UEs / km 2 Due to the nature of the service, mMTC-enabled UEs are likely to be located in shadowed areas not covered by cells (such as basements of buildings), and therefore may require wider coverage than other services provided by 5G communication systems. mMTC-enabled UEs need to be configured as low-cost UEs and may require long battery life because UE batteries are difficult to replace frequently.

[0060] Finally, URLLC is a mission-critical cellular-based wireless communication service that is used for remote control of robots or machinery, industrial automation, drones, telemedicine, emergency alerts, etc., and requires ultra-low latency and ultra-reliable communications. For example, URLLC-enabled services require not only air interface latency of less than 0.5 milliseconds, but also 10 -5 or below the packet error rate. Therefore, for services supporting URLLC, the 5G system needs to provide a transmission time interval (TTI) that is shorter than that of other services, and also requires a design that allocates wide resources within the frequency band. The above-mentioned mMTC, URLLC, and eMBB are only examples of different service types, and the service types applicable to the present disclosure are not limited to the above-mentioned examples.

[0061] The above services considered in the 5G communication system need to be provided in an integrated manner based on a framework. That is, for efficient resource management and control, it is preferred that the services be controlled and transmitted as an integrated system rather than being operated independently.

[0062] In the following, although the embodiments will be described with reference to LTE, LTE-A, LTE Pro or NR systems as examples, these embodiments may also be applied to other communication systems with similar technical backgrounds or channel forms. In addition, without departing from the scope of the present disclosure determined by those skilled in the art, the embodiments may also be applied to other communication systems with some modifications.

[0063] Hereinafter, the frame structure of the 5G system will be described in detail with reference to the accompanying drawings.

[0064] Figure 1 The basic structure of the time-frequency domain is shown. The time-frequency domain is a radio resource area in which data or control channels are transmitted in a 5G system according to an embodiment of the present disclosure.

[0065] refer to Figure 1 , the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The basic unit of resources in the time-frequency domain is a resource element (RE) 1-01, which can be defined by an orthogonal frequency division multiplexing (OFDM) symbol 1-02 on the time axis and a subcarrier 1-03 on the frequency axis. In the frequency domain, N sc RB (For example, 12) consecutive REs may form one resource block (RB) 1-04. In LTE, LTE-A, and LTE-A Pro, two slots each including 7 OFDM symbols are combined to form one subframe 1-10, and one subframe forms a transmission time interval (TTI) as a transmission unit in the time domain.

[0066] Figure 2 The time slot structure considered in the 5G system according to an embodiment of the present disclosure is shown.

[0067] refer to Figure 2 , Figure 2 An example of the structure of a frame 2-00, a subframe 2-01, and a time slot 2-02 is shown. One frame 2-00 may be defined as 10 ms. One subframe 2-01 may be defined as 1 ms. Therefore, one frame 2-00 may include a total of ten subframes 2-01. One time slot 2-02 and 2-03 may be defined as 14 OFDM symbols (i.e., the number of symbols per time slot ( )=14), and one time slot forms a TTI. One subframe 2-01 may include one or more time slots 2-02 and 2-03, and the number of time slots 2-02 and 2-03 of each subframe 2-01 may vary, depending on the set subcarrier spacing values ​​μ 2-04 and 2-05. Figure 2In the example, as the subcarrier spacing values ​​set, μ = 0 (2-04) and μ = 1 (2-05). When μ = 0 (2-04), a subframe 2-01 can include one time slot 2-02; when μ = 1 (2-05), a subframe 2-01 can include two time slots 2-03. That is, the number of time slots per subframe ( ) can vary, depending on the subcarrier spacing value μ set, and the number of time slots per frame ( ) can be changed accordingly. and It can be defined as shown in Table 1.

[0068] [Table 1]

[0069]

[0070] In NR, one component carrier (CC) or serving cell may include up to 250 RBs. Therefore, when the UE always receives the entire serving cell bandwidth as in LTE, the power consumption of the UE may be extreme. To solve this problem, the base station can configure one or more bandwidth parts (BWPs) for the UE, thereby supporting the UE to change the reception area in the cell. In NR, the base station can configure the initial BWP for the UE through the master information block (MIB), which is the bandwidth of the control resource set (CORESET) #0 (or common search space: CSS). Subsequently, the base station can configure the first BWP for the UE through radio resource control (RRC) signaling, and can report at least one BWP configuration information that can be indicated by DCI in the future. The base station can report the BWPID to the UE through DCI, thereby indicating the frequency band used by the UE. When the UE fails to receive DCI in the currently allocated BWP for a specified time or longer, the UE returns to the default BWP and attempts to receive DCI.

[0071] Figure 3 An example of the configuration of a BWP in a 5G communication system according to an embodiment of the present disclosure is shown.

[0072] refer to Figure 3 , Figure 3 An example is shown in which the UE bandwidth 3-00 is configured with two BWPs (ie, BWP#1 3-05 and BWP#2 3-10). The base station may configure one BWP or multiple BWPs for the UE, and may configure information on each BWP as follows.

[0073] [Table 2]

[0074]

[0075] In addition to the above configuration information, various parameters related to the BWP can also be configured for the UE. This information can be sent from the base station to the UE via high-level signaling (e.g., RRC signaling). A configured BWP or at least one of multiple configured BWPs can be activated. Whether to activate the configured BWP can be semi-statically indicated from the base station to the UE via RRC signaling, or dynamically indicated from the base station to the UE via a media access control (MAC) control element (CE) or DCI.

[0076] The configuration of BWP supported by the 5G communication system can be used for various purposes.

[0077] In one example, when the bandwidth supported by the UE is less than the system bandwidth, the configuration of the BWP may be used. For example, the frequency position of the BWP in Table 2 (configuration information 1 in Table 2) may be set for the UE, so that the UE can send and receive data at a specific frequency position within the system bandwidth.

[0078] In another example, the base station may configure multiple BWPs for the UE in order to support different parameter sets. For example, in order for the UE to support data transmission and reception using both 15 kHz subcarrier spacing and 30 kHz subcarrier spacing, two BWPs may be configured to use 15 kHz subcarrier spacing and 30 kHz subcarrier spacing, respectively. Different BWPs may be affected by frequency division multiplexing (FDM). When the UE intends to send and receive data with a specific subcarrier spacing, the BWP configured with that subcarrier spacing may be activated.

[0079] In yet another example, the base station may configure a BWP with a different bandwidth for the UE in order to reduce the power consumption of the UE. For example, when the UE supports a very large bandwidth (e.g., a bandwidth of 100 MHz) and always sends and receives data within the bandwidth, the UE may consume a lot of power. Specifically, the UE unnecessarily monitors the downlink control channel over a large bandwidth of 100 MHz even in the absence of traffic, which is very inefficient in terms of power consumption. Therefore, in order to reduce the power consumption of the UE, the base station may configure a BWP with a relatively small bandwidth, such as a BWP of 20 MHz, for the UE. The UE may perform a monitoring operation in the 20-MHz BWP in the absence of traffic, and the UE may send and receive data using a 100-MHz bandwidth according to instructions from the base station when data is generated.

[0080] Figure 4 A method for dynamically changing the configuration of a BWP according to an embodiment of the present disclosure is shown.

[0081] As shown in Table 2, the base station may configure one BWP or multiple BWPs for the UE, and may report information about the bandwidth of the BWP, the frequency location of the BWP, and the parameter set of the BWP as the configuration of each BWP. Figure 4 An example is shown in which two BWPs (i.e., BPW#1 4-05 and BWP#2 4-10) are configured in UE bandwidth 4-00 for one UE. One or more configured BWPs may be activated, and Figure 4 An example of BWP being activated is shown. Figure 4 , BWP#1 4-05 among the configured BWPs is activated in time slot #0 4-25, and the UE may monitor a physical downlink control channel (PDCCH) in a control region 1 4-45 configured in BWP#1 4-05, and may transmit and receive data 4-55 in BWP#1 4-05. The control region in which the UE receives the PDCCH may vary depending on which BWP among the configured BWPs is activated, and thus the bandwidth in which the UE monitors the PDCCH may vary.

[0082] The base station may also send an indicator for switching the configuration of the BWP to the UE. Here, switching the configuration of the BWP may be considered to be the same as activating a specific BWP (e.g., switching the activated BWP from BWP A to BWP B). The base station may send a configuration switching indicator to the UE in a specific time slot. After receiving the configuration switching indicator from the base station, the UE may determine the BWP to be activated by applying the changed configuration according to the configuration switching indicator from the specific time, and may monitor the PDCCH in the control region configured in the activated BWP.

[0083] refer to Figure 4 , the base station may send a configuration switching indicator 4-15 to the UE in time slot #1 4-30 indicating that the activated BWP is switched from the current BWP #1 4-05 to the BWP #2 4-10. After receiving the indicator, the UE may activate the BWP #2 4-10 according to the content of the indicator. Here, the UE may require a transition time 4-20 for the BWP switching, and the time for switching and applying the BWP to be activated may be determined according to the transition time. Reference Figure 4 , after receiving the configuration switching indicator 4-15, a transition time 4-20 of one time slot is required. Data transmission and reception may not be performed during the transition time, that is, a guard period (GP) 4-60 may be set. Therefore, BWP#2 4-10 may be activated in time slot#2 4-35, so the UE may transmit and receive a control channel 4-50 and data 4-55 via the BWP in time slot#2 4-35 and time slot#3 4-40.

[0084] The base station may pre-configure one or more BWPs for the UE via upper layer signaling (eg, RRC signaling), and may indicate activation by mapping the configuration switch indicator 4-15 with one of the BWP configurations pre-configured by the base station. 2 The N-bit indicator may indicate one BWP selected from among N pre-configured BWPs. Table 3 shows an example of indicating configuration information about a BWP using a two-bit indicator.

[0085] [Table 3]

[0086]

[0087] The above-mentioned configuration switching indicators 4 - 15 for BWP may be transmitted from the base station to the UE via MAC CE signaling or L1 signaling (eg, common DCI, group-common DCI, or UE-specific DCI).

[0088] The time of applying BWP activation according to the configuration switching indicator 4-15 for BWP described above depends on the following. The time of applying configuration switching to the UE may depend on a predefined value (e.g., the configuration switching is N ( 1) time slots later), can be set by the base station for the UE via upper layer signaling (e.g., RRC signaling), or can be sent via the configuration switching indicator 4-15. In addition, the time to apply the configuration switching can be determined by combining two or more of the above methods. After receiving the configuration switching indicator 4-15 for BWP, the UE can start applying the switched configuration from the time obtained by the above method.

[0089] Hereinafter, a downlink control channel in a 5G communication system will be described in detail with reference to the accompanying drawings.

[0090] Figure 5 An example of a control region (ie, CORESET) for transmitting a downlink control channel in a 5G wireless communication system according to an embodiment of the present disclosure is shown.

[0091] Figure 5An example is shown in which a UE BWP 5-10 is configured on the frequency axis and two control regions (control region #1 5-01 and control region #2 5-02) are configured in one time slot 5-20 on the time axis. Control region #1 5-01 and control region #2 5-02 may be configured in a specific frequency resource 5-03 in the entire UE BWP 5-10 on the frequency axis. Each control region may be configured with one or more OFDM symbols on the time axis, which may be defined as a control region set duration 5-04.

[0092] refer to Figure 5 , control region #1 5-01 is configured with a control resource set duration of two symbols, while control region #2 5-02 is configured with a control resource set duration of one symbol.

[0093] The control region in the above 5G can be configured by the base station for the UE through upper layer signaling (e.g., system information, MIB or RRC signaling). Configuring the control region for the UE means that the base station provides information to the UE, such as the identification of the control region, the frequency position of the control region, the symbol duration of the control region, etc. For example, the configuration of the control region may include the multiple pieces of information shown in Table 4.

[0094] [Table 4]

[0095]

[0096] In Table 4, tci-StatesPDCCH (hereinafter, referred to as transmission configuration indicator (TCI) state) configuration information may include information about the index of one or more synchronization signal (SS) / physical broadcast channel (PBCH) blocks or the index of a channel state information reference signal (CSI-RS) that is in a quasi co-location (QCL) relationship with a demodulation reference signal (DMRS) transmitted in the control region.

[0097] Hereinafter, a method for allocating time-frequency resources for data transmission in NR will be described.

[0098] In addition to the frequency domain resource candidate allocation indicated by the BWP shown above, NR also provides the following specific frequency domain resource allocation (FD-RA).

[0099] Figure 6 It shows three frequency domain resource allocation methods, namely type 0 6-00, type 1 6-05 and dynamic switching 6-10, which can be configured by the upper layer in NR according to an embodiment of the present disclosure.

[0100] refer to Figure 6, when the UE is configured to use only resource type 0 (6-00) through upper layer signaling, some downlink control information (DCI) used to allocate PDSCH to the UE has N RBG Here, according to the BWP size allocated by the BWP indicator and the upper layer parameter rbg-Size and the RBG phase indicated by 1 in the bitmap, N RBG indicates the number of resource block groups (RBGs) as determined in Table 4, and data is transmitted on the RBGs indicated by 1 according to the bitmap.

[0101] [Table 5]

[0102]

[0103] When the UE is configured to use only resource type 1 6-05 through upper layer signaling, some DCIs used to allocate PDSCH to the UE have The base station may configure the starting virtual resource block (VRB) 6-20 and the length 6-25 of the frequency domain resources continuously allocated therefrom.

[0104] When the UE is configured to use both resource type 0 and resource type 1 (6-10) through upper layer signaling, some DCIs for allocating PDSCH to the UE have frequency domain resource allocation information of bits 6-15 for configuring a payload of resource type 0 and 6-35 of a larger value among payloads 6-20 and 6-25 for configuring resource type 1, the conditions of which will be described later. Here, one bit 6-30 is added to the most significant bit (MSB) of the frequency domain resource allocation information in the DCI, where 0 indicates the use of resource type 0 and 1 indicates the use of resource type 1.

[0105] Figure 7 An example of time domain resource allocation in NR according to an embodiment of the present disclosure is shown.

[0106] refer to Figure 7 , the base station can calculate the scheduling offset (K 0 ) value and the subcarrier spacing of the data channel and control channel configured by DCI ( ) The starting position 7-00 and length 7-05 of the OFDM symbol in the time slot 7-10 dynamically indicated are used to indicate the time domain position of the PDSCH resource allocated to the UE.

[0107] Figure 8 An example of time domain resource allocation according to subcarrier spacing of a data channel and a control channel according to an embodiment of the present disclosure is shown.

[0108] refer to Figure 8, when the data channel and the control channel have the same subcarrier spacing (8-00, ), since the number of data time slots and the number of control time slots are the same, the base station and the UE identify the scheduling offset according to the predetermined time slot offset K 0 When the subcarrier spacing of the data channel is different from the subcarrier spacing of the control channel (8-05, ), since the number of data time slots and the number of control time slots are different, the base station and the UE identify the scheduling offset according to the predetermined time slot offset K 0 Occurs based on the subcarrier spacing of the PDCCH.

[0109] In NR, for efficient control channel reception of UE, various types of DCI as shown in Table 6 are provided according to various purposes.

[0110] [Table 6]

[0111]

[0112] For example, the base station may schedule a PDSCH for one cell using DCI format 1_0 or DCI format 1_1.

[0113] DCI format 0_1 ​​includes at least the following information when transmitted together with a CRC scrambled with a cell radio network temporary identifier (C-RNTI), a configured scheduling RNTI (CS-RNTI), or a new RNTI.

[0114] * Identifier for DCI format (1 bit): DCI format indicator, which is always set to 1.

[0115] * Frequency domain resource allocation (N RBG bit or bit): indicates frequency domain resource allocation. When monitoring DCI format 1_0 in the UE-specific search space, is the size of the active DL BWP; otherwise, is the size of the initial DL BWP. N RBG is the number of resource block groups. The detailed method is described in the above frequency domain resource allocation.

[0116] * Time domain resource allocation (bits 0 to 4): indicates the time domain resource allocation according to the above description.

[0117] * VRB-to-PRB mapping (1 bit): 0 indicates non-interleaved VRP-to-PRB mapping, and 1 indicates interleaved VRP-to-PRB mapping.

[0118] * Modulation and coding scheme (5 bits): Indicates the modulation order and coding rate used for PDSCH transmission.

[0119] * New data indicator (1 bit): Depending on toggling, indicates whether the PDSCH corresponds to an initial transmission or a retransmission.

[0120] * Redundancy version (2 bits): Indicates the redundancy version used for PDSCH transmission.

[0121] * Hybrid Automatic Repeat Request (HARQ) process number (4 bits): indicates the HARQ process number used for PDSCH transmission.

[0122] * Downlink Allocation Index (DAI) (2 bits): DAI indicator.

[0123] * Transmit power control (TPC) command for scheduled PUCCH (2 bits): PUCCH power control indicator.

[0124] * PUCCH resource indicator (3 bits): PUCCH resource indicator, which indicates one of eight resources configured via upper layers.

[0125] * PDSCH-to-HARQ_feedback timing indicator (3 bits): HARQ feedback timing indicator, which indicates one of eight feedback timing offsets configured via upper layers.

[0126] DCI format 1_1 includes at least the following information when transmitted together with a CRC scrambled with a cell radio network temporary identifier (C-RNTI), a configured scheduling RNTI (CS-RNTI), or a new RNTI.

[0127] * Identifier for DCI format (1 bit): DCI format indicator, which is always set to 1.

[0128] * Carrier indication (0 or 3 bits): Indicates the CC (or cell) in which the PDSCH allocated by the DCI is transmitted.

[0129] * Bandwidth part indicator (0, 1 or 2 bits): Indicates the BWP in which the PDSCH allocated by the DCI is transmitted.

[0130] * Frequency domain resource allocation (payload is determined according to the above frequency domain resource allocation): indicates frequency domain resource allocation. is the size of the active DL BWP. The detailed method is shown in the above frequency domain resource allocation.

[0131] * Time domain resource allocation (bits 0 to 4): indicates the time domain resource allocation according to the above description.

[0132] * VRB-to-PRB mapping (0 or 1 bit): 0 indicates non-interleaved VRP-to-PRB mapping, and 1 indicates interleaved VRP-to-PRB mapping. When frequency domain resource allocation is set to resource type 0, this information is 0 bit.

[0133] * PRB bundling size indicator (0 or 1 bit): When the upper layer parameter prb-BundlingType is not set or is set to 'static', this information is 0 bit; when the upper layer parameter prb-BundlingType is set to 'dynamic', this information is 1 bit.

[0134] * Rate match indicator (0, 1 or 2 bits): Indicates the rate matching mode.

[0135] * Zero-power (ZP) CSI-RS trigger (0, 1, or 2 bits): an indicator to trigger aperiodic ZP CSI-RS.

[0136] * For transport block 1:

[0137] ** Modulation and coding scheme (5 bits): Indicates the modulation order and coding rate used for PDSCH transmission.

[0138] ** New data indicator (1 bit): Depending on toggling, indicates whether the PDSCH corresponds to an initial transmission or a retransmission.

[0139] ** Redundancy version (2 bits): Indicates the redundancy version used for PDSCH transmission.

[0140] * For transport block 2:

[0141] ** Modulation and coding scheme (5 bits): Indicates the modulation order and coding rate used for PDSCH transmission.

[0142] ** New data indicator (1 bit): Depending on toggling, indicates whether the PDSCH corresponds to an initial transmission or a retransmission.

[0143] ** Redundancy version (2 bits): Indicates the redundancy version used for PDSCH transmission.

[0144] * HARQ process number (4 bits): indicates the HARQ process number used for PDSCH transmission.

[0145] * Downlink Allocation Index (0, 2 or 4 bits): DAI indicator.

[0146] * TPC command for scheduled PUCCH (2 bits): PUCCH power control indicator.

[0147] * PUCCH resource indicator (3 bits): PUCCH resource indicator, which indicates one of eight resources configured via upper layers.

[0148] * PDSCH-to-HARQ_feedback timing indicator (3 bits): HARQ feedback timing indicator, which indicates one of eight feedback timing offsets configured via upper layers.

[0149] * Antenna port (4, 5, or 6 bits): Indicates the DMRS port and the code division multiplexing (CDM) group without data.

[0150] * Transmission Configuration Indicator (0 or 3 bits): TCI indicator.

[0151] * Sounding Reference Signal (SRS) Request (2 or 3 bits): SRS transmission request indicator.

[0152] * Code block group (CBG) transmission information (0, 2, 4, 6, or 8 bits): An indicator indicating whether the code block group in the allocated PDSCH is transmitted. 0 indicates that the CBG is not transmitted, and 1 indicates that the CBG is transmitted.

[0153] * CBG flushing-out information (0 or 1 bit): An indicator indicating whether the previous CBG is contaminated. 0 indicates that the CBG may be contaminated, and 1 indicates that the CBG may be combinable in retransmission reception.

[0154] * DMRS sequence initialization (0 or 1 bit): DMRS scrambling ID selection indicator.

[0155] The number of DCIs with different sizes that a UE can receive in each time slot in a cell is up to 4. The number of DCIs with different sizes that a UE can receive in each time slot in a cell is up to 3 and scrambled with C-RNTI.

[0156] Fig. 9 A radio protocol structure of a base station and a UE when a single cell 9-00, carrier aggregation (CA) 9-10, and dual connectivity (DC) 9-20 are performed according to an embodiment of the present disclosure is shown.

[0157] refer to Fig. 9 The wireless protocols of the next generation mobile communication system include NR Service Data Adaptation Protocol (SDAP) 9-25 and 9-70, NR Packet Data Convergence Protocol (PDCP) 9-30 and 9-65, NR Radio Link Control (RLC) 9-35 and 9-60, and NR Medium Access Control (MAC) 9-40 and 9-55 at the UE and NR base station, respectively.

[0158] The main functions of NR SDAP 9-25 and 9-70 may include some of the following functions.

[0159] - User plane data transmission

[0160] - Mapping between QoS flows and DRBs for both DL and UL

[0161] - Marking of QoS flow ID in both DL and UL packets

[0162] - Reflective QoS Flow-to-DRB mapping for UL SDAP PDU

[0163] For SDAP layer devices, the UE can receive configurations about whether to use the header of the SDAP layer device or whether to use the functions of the SDAP layer device for each PDCP layer device, each bearer or each logical channel via an RRC message. When configuring the SDAP header, a one-bit NAS QoS reflection indicator (NAS reflection QoS) and a one-bit AS QoS reflection indicator (AS reflection QoS) of the SDAP header can be used to indicate QoS flows and mapping information that enable the UE to update or reconfigure the uplink and downlink QoS for data bearers. The SDAP header may include QoS flow ID information indicating QoS. QoS information may be used as data processing priority, scheduling information, etc., in order to support desired services.

[0164] The main functions of NR PDCP 9-30 and 9-65 may include some of the following functions.

[0165] - Header compression and decompression (ROHC only)

[0166] - Transmission of user data

[0167] - Sequential delivery of upper layer PDUs

[0168] - Out-of-order delivery of upper layer PDUs

[0169] - Reordering of received PDCP PDUs

[0170] - Duplicate detection of lower layer SDU

[0171] - Retransmission of PDCP SDU

[0172] - Encryption and decryption

[0173] - Timer based SDU discard in uplink.

[0174] Among the above functions, the reordering function of the NR PDCP device refers to a function of rearranging the PDCP PDUs received at the lower layer in order based on the PDCP sequence number (SN), and may include a function of sending data to the upper layer in a rearranged order or a function of sending data immediately regardless of the order. In addition, the reordering function may include a function of recording lost PDCP PDUs via reordering, may include a function of reporting the status of lost PDCP PDUs to the transmitter, and may include a function of requesting retransmission of lost PDCP PDUs.

[0175] The main functions of NR RLC 9-35 and 9-60 may include some of the following functions.

[0176] - Transmission of upper layer PDU

[0177] - Sequential delivery of upper layer PDUs

[0178] - Out-of-order delivery of upper layer PDUs

[0179] - Error correction via ARQ

[0180] - Concatenation, segmentation and reassembly of RLC SDU

[0181] - Re-segmentation of RLC data PDUs

[0182] - Reordering of RLC data PDUs

[0183] - Duplicate detection

[0184] - Protocol error detection

[0185] - RLC SDU discarded

[0186] - RLC Reconstruction

[0187] Among the above functions, the sequential delivery function of the NR RLC device refers to a function of delivering the RLC SDU received from the lower layer to the upper layer in sequence, and may include a function of reorganizing and delivering multiple RLC SDUs when one original RLC SDU is divided into multiple RLC SDUs to be received. In addition, the sequential delivery function may include a function of rearranging the received RLC PDU based on the RLC SN or PDCP SN, and may include a function of recording the lost RLC PDU via reordering. In addition, the sequential delivery function may include a function of reporting the status of the lost RLC PDU to the transmitter, may include a function of requesting retransmission of the lost RLC PDU, and if there is a lost RLC SDU, may include a function of delivering only the RLC SDU before the lost RLC SDU to the upper layer in sequence. In addition, the sequential delivery function may include a function of delivering all RLC SDUs received before the start of the timer (although there are lost RLC SDUs) to the upper layer in sequence when the timer expires, or may include a function of delivering all RLC SDUs received so far (although there are lost RLC SDUs) to the upper layer in sequence when the timer expires. In addition, the NR RLC device can process the RLC PDU in the order of reception (the order of arrival regardless of the order of SN), and can deliver the RLC PDU to the PDCP device in an unordered manner. For segmentation, the NR RLC device can receive segments stored in a buffer or to be received later, can reconstruct the segments into a complete RLC PDU, can process the RLC PDU, and can deliver the RLC PDU to the PDCP device. The NR RLC layer may not include a tandem function, and the tandem function may be performed in the NR MAC layer or may be replaced by a multiplexing function of the NR MAC layer.

[0188] The out-of-order delivery function of the NR RLC device refers to a function of directly delivering the RLC SDU received from the lower layer to the upper layer regardless of the order, and may include a function of reassembling and delivering multiple RLC SDUs when one original RLC SDU is divided into multiple RLC SDUs to be received. In addition, the out-of-order delivery function may include a function of recording the lost RLC PDU by storing and reordering the RLC SN or PDCP SN of the received RLC PDU.

[0189] NR MAC 9-40 and 9-55 can be connected to multiple NR RLC layer devices configured in one device, and the main functions of NR MAC can include some of the following functions.

[0190] - Mapping between logical channels and transport channels

[0191] - Multiplexing / demultiplexing of MAC SDU

[0192] - Dispatch information report

[0193] - Error correction through HARQ

[0194] - Prioritization between logical channels of a UE

[0195] - Prioritization between UEs through dynamic scheduling

[0196] - MBMS service identifier

[0197] - Transmission format selection

[0198] - Filling

[0199] The NR PHY layers 9-45 and 9-50 may perform channel coding and modulation of upper layer data, and convert the data into OFDM symbols to transmit the OFDM symbols via a wireless channel, or demodulate the OFDM symbols received via a wireless channel, and perform channel decoding of the OFDM symbols to deliver the OFDM symbols to an upper layer.

[0200] The details of the wireless protocol structure can be changed differently according to the carrier (or cell) operation method. For example, when the base station sends data to the UE based on a single carrier (or cell), the base station and the UE use a protocol structure with each layer having a single structure as in 9-00. When the base station sends data to the UE based on carrier aggregation (CA) using multiple carriers at a single TRP, the base station and the UE use a protocol structure as in 9-10, where at most RLC has a single structure but the PHY layer is multiplexed through the MAC layer. In another example, when the base station sends data to the UE based on a connection (DC) using multiple carriers at multiple TRPs, the base station and the UE use a protocol structure as in 9-20, where at most RLC has a single structure but the PHY layer is multiplexed through the MAC layer.

[0201] With reference to the details of the PDSCH transmission / reception process, such as the above-mentioned DCI structure, PDSCH time / frequency resource allocation, and radio protocol structure, the NR system of Release 15 focuses on the allocation of PDSCHs transmitted from a single transmission point. Therefore, in coordinated communication in which one UE receives PDSCHs transmitted from multiple points, additional standards need to be supported. For example, in the current NR, when two or more PDSCHs are scheduled for a UE in the same transmission band and overlapping time periods, the UE is not forced to decode all PDSCHs (except in special cases where a PDSCH for transmitting a system information block (SIB) is included, etc.). In addition, in the current NR, when two or more PDSCHs are scheduled in an overlapping time period, the UE assumes that the PDSCHs may have different priorities. Therefore, in this case, a specific UE may operate to decode only a PDSCH with a high priority. However, in coordinated communication, since the UE needs to decode all PDSCHs transmitted from multiple points, the existing standards related to PDSCH priority need to be extended. In addition, the UE requires a high performance receiver for PDSCH reception from multiple TRPs and involves high UE complexity in order to support coordinated communication. Therefore, a method for reducing the UE complexity for supporting coordinated communication is needed.

[0202] The present disclosure illustrates an embodiment of improving the efficiency of coordinated communications by providing a PDSCH prioritization method and a method for reducing UE reception complexity in consideration of coordinated communications.

[0203] The following details apply to both frequency division duplex (FDD) and time division duplex (TDD) systems.

[0204] In the following disclosure, upper layer signaling is a method of transmitting a signal from a base station to a UE using a downlink data channel of a physical layer or from a UE to a base station using an uplink data channel of a physical layer, and may also be referred to as RRC signaling, PDCP signaling, or MAC Control Element (CE).

[0205] In the following disclosure, when determining whether coordinated communication is applied, the UE may use various methods, such as allowing (multiple) PDCCHs for allocating PDSCHs to which coordinated communication is applied to have a specific format, allowing (multiple) PDCCHs for allocating PDSCHs to which coordinated communication is applied to include a specific indicator indicating whether communication is applied, scrambling (multiple) PDCCHs for allocating PDSCHs to which coordinated communication is applied with a specific RNTI, or assuming that coordinated communication is applied within a specific time period indicated via an upper layer. Hereinafter, for ease of description, a UE receiving a PDSCH to which coordinated communication is applied based on conditions similar to the above is referred to as a non-coherent joint transmission (NC-JT) case.

[0206] In the following disclosure, prioritizing A and B may be interpreted in various ways, such as selecting a higher priority to execute an operation corresponding thereto according to a predetermined priority rule, or omitting, skipping, or dropping an operation corresponding to a lower priority.

[0207] In the following disclosure, the above examples will be described with reference to multiple embodiments, which may not be independent, and one or more embodiments may be applied simultaneously or in combination.

[0208] First embodiment: Multiple DCI reception for NC-JT

[0209] Unlike conventional systems, 5G wireless communication systems can support not only services requiring high transmission rates, but also services with extremely short transmission delays and services requiring high connection density. In a wireless communication network including multiple cells, TRPs or beams, coordinated transmission between cells, TRPs and / or beams is a basic technology for meeting the above-mentioned various service requirements by increasing the strength of the signal received by the UE or effectively controlling the interference between cells, TRPs and / or beams.

[0210] Joint transmission (JT) is a representative transmission technology for coordinated communication and supports one UE to pass through different cells, TRPs or / and beams, thereby increasing the strength of the signal received by the UE. Since the channels between the UE and each cell, TRP or / and beam may have significantly different characteristics, different types of precoding, modulation and coding schemes (MCS), resource allocation, etc. need to be applied to the link between the UE and each cell, TRP or / and beam. Specifically, in non-coherent joint transmission (NC-JT) supporting non-coherent interfering coding for each cell, TRP or / and beam, it is important to configure the individual DL transmission information for each cell, TRP or / and beam. The configuration of the individual DL transmission information for each cell, TRP or / and beam is the main factor in increasing the payload required for DL ​​DCI transmission, which may adversely affect the reception performance of the PDCCH used to send DCI. Therefore, in order to support JT, it is necessary to carefully design a trade-off between the number of DCIs and the reception performance of the PDCCH.

[0211] Fig.10 An example of radio resource allocation for each TRP according to the JT technique and according to an embodiment of the present disclosure is shown.

[0212] refer to Fig.10, 10-00 shows coherent joint transmission (C-JT) supporting coherent precoding between individual cells, TRPs or / and beams. In C-JT, TRP A 10-05 and TRP B 10-10 send the same data (or PDSCH) to UE 10-15, and multiple TRPs perform joint precoding, which means that TRP A 10-05 and TRP B 10-10 send the same DMRS port (for example, both TRPs send DMRS ports A and B) for receiving the same PDSCH. In this case, UE10-15 receives a DCI for receiving one PDSCH demodulated by DMRS ports A and B.

[0213] refer to Fig.10 , 10-20 shows non-coherent joint transmission (NC-JT) supporting non-coherent precoding between individual cells, TRPs or / and beams. In NC-JT, individual cells, TRPs or / and beams send different data (or PDSCHs), and separate precoding can be applied to each data (or PDSCH), which means that TRP A 10-25 and TRP B 10-30 send different DMRS ports for receiving different PDSCHs to UE10-35 (for example, TRP A sends DMRS port A and TRP B sends DMRS port B). In this case, UE 10-35 receives two types of DCI for receiving PDSCH A demodulated by DMRS port A and PDSCH B demodulated by DMRS port B.

[0214] For example, in NC-JT, Fig.10 As shown at the bottom of , various radio resource allocations can be considered, such as the case where multiple TRPs use the same frequency and time resources (10-40), the case where the frequency and time resources used by multiple TRPs never overlap (10-45), and the case where the frequency and time resources used by multiple TRPs partially overlap (10-50). Specifically, in the case of 10-50, the DCI payload required for the resource allocation information increases linearly according to the number of TRPs. Such an increase in the DL DCI payload may adversely affect the reception performance of the PDCCH used to send the DCI, or may significantly increase the DCI blind decoding complexity of the UE as described above. Therefore, the present disclosure provides a PDSCH time-frequency resource allocation method for effectively supporting NC-JT.

[0215] To support NC-JT, various forms, structures, and relationships of DCI may be considered to simultaneously allocate multiple PDSCHs to a UE.

[0216] Fig.11Four examples of DCI design for supporting NC-JT according to embodiments of the present disclosure are shown.

[0217] refer to Fig.11 , in case #1 11-00, N-1 different PDSCHs are transmitted in N-1 additional TRPs (TRP #1 to TRP #N-1) in addition to the serving TRP (TRP #0) used when transmitting a single PDSCH. Case #1 11-00 shows an example in which control information about the PDSCH transmitted in the additional TRP is transmitted in the same DCI format as the DCI format of the control information about the PDSCH transmitted in the serving TRP. That is, the UE obtains control information about the PDSCH transmitted in different TRPs (TRP #0 to TRP #N-1) through DCI (i.e., DCI #0 to DCI #N-1) having the same DCI format and the same payload. In case #1, the degree of freedom of each PDSCH control (allocation) is fully guaranteed, whereas when respective DCIs are transmitted in different TRPs, reception performance may deteriorate due to the different coverage of each DCI.

[0218] refer to Fig.11, in case #2 11-05, N-1 different PDSCHs are transmitted in N-1 additional TRPs (TRP #1 to TRP #N-1) outside the serving TRP (TRP #0) used when transmitting a single PDSCH. Case #2 11-05 shows an example in which control information about the PDSCH transmitted in the additional TRP is transmitted in a form different from that of the control information about the PDSCH transmitted in the serving TRP (different DCI format or different DCI payload). For example, DCI #0 that transmits control information about the PDSCH transmitted in the serving TRP (TRP #0) may include all information elements of DCI format 1_0 or DCI format 1_1, while shortened DCI (sDCI #0 to sDCI #N-2) that transmits control information about the PDSCH transmitted in the collaborative TRPs (TRP #1 to TRP #N-1) may include some information elements of DCI format 1_0 or DCI format 1_1. Therefore, the sDCI that sends control information about the PDSCH sent in the collaborative TRP may have a smaller payload than the normal DCI (nDCI) that sends control information about the PDSCH sent in the serving TRP, or may include as many reserved bits as the number of bits is less than that of the nDCI. In case #2, the degree of freedom of each PDSCH control (allocation) may be limited depending on the content of the information elements included in the sDCI, while the reception performance of the sDCI may be improved compared to that of the nDCI, so that differences in the coverage of each DCI are less likely to occur.

[0219] refer to Fig.11, in case #3 11-10, N-1 different PDSCHs are transmitted in N-1 additional TRPs (TRP #1 to TRP #N-1) in addition to the serving TRP (TRP #0) used when transmitting a single PDSCH. Case #3 11-10 shows another example in which control information about the PDSCH transmitted in the additional TRP is transmitted in a form different from that of the control information about the PDSCH transmitted in the serving TRP (different DCI format or different DCI payload). For example, DCI #0 that transmits control information about the PDSCH transmitted in the serving TRP (TRP #0) may include all information elements of DCI format 1_0 or DCI format 1_1, while control information about the PDSCH transmitted in the collaborative TRPs (TRP #1 to TRP #N-1) may be transmitted by collecting only some information elements of DCI format 1_0 or DCI format 1_1 in one secondary DCI (sDCI). For example, the sDCI may include at least one of HARQ-related information such as frequency domain resource allocation, time domain resource allocation, and MCS of the collaborative TRP. In addition, for information not included in the sDCI (such as a BWP indicator or a carrier indicator), the information in the DCI (DCI #0, normal DCI, or nDCI) of the service TRP may be followed. In case #3, the degree of freedom of each PDSCH control (allocation) may be limited depending on the content of the information element included in the sDCI, while the reception performance of the sDCI can be adjusted, and the DCI blind decoding complexity of the UE is lower than that of case #1 or #2.

[0220] refer to Fig.11 , in case #4 11-15, N-1 different PDSCHs are transmitted in N-1 additional TRPs (TRP #1 to TRP #N-1) in addition to the serving TRP (TRP #0) used when transmitting a single PDSCH. Case #4 11-15 shows an example in which control information about the PDSCH transmitted in the additional TRP is transmitted with the same DCI (long DCI: lDCI) as the DCI used for control information about the PDSCH transmitted in the serving TRP. That is, the UE obtains control information about the PDSCH transmitted in different TRPs (TRP #0 to TRP #N-1) through a single DCI. In case #4, the DCI blind decoding complexity of the UE is not increased, while the degree of freedom of PDSCH control (allocation) is low, for example, the number of collaborative TRPs is limited according to the limitation of the long DCI payload.

[0221] In the following description and embodiments, sDCI may refer to various auxiliary DCIs including PDSCH control information transmitted in a collaborative TRP, such as shortened DCI, secondary DCI, or normal DCI (the above-mentioned DCI format 1_0 or 1_1). In addition, unless otherwise specified, the foregoing description may be similarly applied to these various auxiliary DCIs.

[0222] In the following description and embodiments, case #1 11-00, case #2 11-05, and case #3 11-10 in which one or more DCI (PDCCH) are used to support NC-JT are classified as NC-JT based on multiple PDCCHs, and case #4 11-15 in which a single DCI (PDCCH) is used to support NC-JT is classified as NC-JT based on a single PDCCH.

[0223] In the following description and embodiments, a PDSCH prioritization method considering NC-JT based on multiple PDCCHs and NC-JT based on a single PDCCH and a method for reducing UE complexity for NC-JT are provided.

[0224] In an embodiment, when actually applied, "collaborative TRP" may be replaced by various terms, such as "collaborative panel" or "collaborative beam".

[0225] In an embodiment, although "when NC-JT is applied" can be interpreted in various ways depending on the situation, such as "when the UE simultaneously receives one or more PDSCHs in one BWP", "when the UE simultaneously receives two or more TCI indications in one BWP", or "when the PDSCH received by the UE is associated with one or more DMRS port groups", for ease of explanation, one expression is adopted.

[0226] In the present disclosure, various wireless protocol structures can be used for NC-JT according to the TRP deployment scenario. For example, when there is no backhaul delay between the cooperating TRPs or the backhaul delay between the cooperating TRPs is short, a structure similar to Fig. 9 However, when the backhaul delay between the cooperating TRPs is too long to be ignored (for example, when the CSI exchange or scheduling information exchange between the cooperating TRPs takes 2 ms or more), a structure in which the TRP is independent of the RLC layer (similar to the Fig. 9 9-20), thereby ensuring robustness to delay (i.e., a DC-like approach).

[0227] Second embodiment: Method for prioritizing PDSCH

[0228] This embodiment provides a specific method for prioritizing PDSCHs when two or more PDSCHs are scheduled in the same transmission band (eg, the same transmission band, the same component carrier, or the same BWP) and in overlapping time resources as described in the first embodiment.

[0229] Fig.12 The priority of PDSCH in the current NR and the priority of PDSCH according to an embodiment of the present disclosure are shown.

[0230] refer to Fig.12 In the current NR, when two or more PDSCHs for a UE are scheduled in the same transmission frequency band and overlapping time period, the UE is not forced to decode all PDSCHs (except in special cases where a PDSCH for transmitting SIBs, etc. is included therein). In addition, in the current NR, when two PDSCHs are scheduled in the overlapping time period, the UE assumes that the PDSCHs may have different priorities. Specifically, scheduling information about the two PDSCHs is reported to the UE via DCI or a semi-static method (12-05 and 12-10), where it is assumed that PDSCH 12-15 scheduled by DCU 2 (ie, 12-10) reported later in time sequence has a higher priority (12-01) than PDSCH 12-20 scheduled by DCI 1 (ie, 12-05) reported earlier in time sequence. Here, the UE may operate in various ways, for example, depending on the implementation, only the PDSCH with a higher priority may be decoded or both the PDSCH with a higher priority and the PDSCH with a lower priority may be decoded.

[0231] However, when using NC-JT, the UE and the base station expect all PDSCHs scheduled in a specific time resource to be decoded, so it is necessary to change the PDSCH priority as described above in the NR. Reasonable design of PDSCH priority ensures that the UE decodes all PDSCHs used for NC-JT, so that the UE can essentially only decode PDSCHs with high priority among other PDSCHs, and autonomously determine whether to decode PDSCHs with low priority, thereby reducing UE complexity.

[0232] For prioritization, the following principles may be considered. I) When the PDSCHs scheduled by different DCIs 12-25 and 12-30 in overlapping time resources are PDSCHs 12-35 and 12-40 for NC-JT, these PDSCHs need to have the same priority so that the UE decodes all PDSCHs (12-21). II) When the PDSCHs scheduled by different DCIs 12-05 and 12-10 in overlapping time resources are PDSCHs 12-15 and 12-20 not used for NC-JT, different priorities may be applied to these PDSCHs. In order to apply these principles, it is necessary to distinguish between PDSCHs for NC-JT and PDSCHs not used for NC-JT. To this end, the following examples may be considered.

[0233] A. The time difference between PDSCHs scheduled in overlapping time resources (K 0 ) and PDSCH scheduling information notification time: When multiple PDSCHs are scheduled in overlapping time resources, the UE can use the K of each PDSCH 0 The value distinguishes whether each PDSCH is used for NC-JT. For example, the UE can determine whether the PDSCH with the same K 0 The PDSCH with different K values ​​is the PDSCH for NC-JT, and it can be determined that 0 The PDSCH with the value is not used for NC-JT. When the backhaul transmission delay time of each transmission point is similar or predictable, the PDSCH scheduling information notification time or K 0 This example may be useful when the values ​​may match equally. In another example, the UE may determine K between PDSCHs. 0 The difference between the values ​​is within a certain value (in Fig.12 The PDSCHs whose |xy| is within a specific value) are PDSCHs for NC-JT, and it can be determined that the other PDSCHs are PDSCHs not used for NC-JT. When it is difficult to match the scheduling information notification time of the PDSCH or K due to the different return delay times of the various transmission points 0 This example can be useful when .

[0234] B. TCI information about PDSCH scheduled in overlapping time resources: When multiple PDSCHs are scheduled in overlapping time resources, if a TCI indicator (such as DCI) is included in the PDSCH scheduling information, the UE can distinguish whether each PDSCH is used for NC-JT by the corresponding TCI indicator. For example, the UE can determine that a PDSCH with a different TCI indicator is a PDSCH for NC-JT, and can determine that a PDSCH with the same TCI indicator is a PDSCH not used for NC-JT. This example can be useful when the transmit / receive beams used for each transmission point are different or the channel characteristics are significantly different.

[0235] C. Information about antenna ports or DMRS CDM groups of PDSCHs scheduled in overlapping time resources: When multiple PDSCHs are scheduled in overlapping time resources, the UE can distinguish whether each PDSCH is used for NC-JT by the antenna port or DMRS CDM group assignment of the PDSCH. For example, the UE can determine that a PDSCH with non-overlapping assigned antenna ports or DMRS CDM groups is a PDSCH for NC-JT, and can determine that a PDSCH with at least one overlapping assigned antenna port or DMRS CDM group is a PDSCH not used for NC-JT. This example can be useful when the UE receives data sent from various transmission points via different layers.

[0236] D. HARQ process information about PDSCH scheduled in overlapping time resources: When multiple PDSCHs are scheduled in overlapping time resources, the UE can distinguish whether each PDSCH is used for NC-JT by the HARQ process number assigned to the PDSCH. For example, the UE can determine that PDSCHs with the same HARQ process number are PDSCHs for NC-JT, and can determine that PDSCHs with different HARQ process numbers are PDSCHs not used for NC-JT. This example can be useful when managing retransmission of all data sent via NC-JT in one HARQ process.

[0237] E. RNTI information associated with PDSCH scheduled in overlapping time resources: When multiple PDSCHs are scheduled in overlapping time resources, the UE can distinguish whether each PDSCH is used for NC-JT by scrambling the scheduling information with respect to the RNTI of the PDSCH. For example, there may be an RNTI not used for NC-JT, or there may be an RNTI only used for NC-JT. The RNTI not used for NC-JT may be an RNTI used for semi-persistent scheduling.

[0238] Examples A to E are not mutually exclusive, and two or more examples may be used in combination. For example, using examples A and B simultaneously, only PDSCHs that meet the conditions specified in both examples may be determined as PDSCHs for NC-JT. Although various other combinations are possible, not all possibilities are listed to avoid confusing the subject matter of the present description. In addition to the above examples, similar methods for distinguishing PDSCHs for NC-JT may be used.

[0239] When the PDSCH for NC-JT is distinguished, the UE and the base station may set the same priority for the PDSCH for NC-JT, or may set different priorities for the respective PDSCHs not used for NC-JT. In addition, when the PDSCH for NC-JT and the PDSCH not used for NC-JT are mixed, different priorities may be set for the PDSCHs 12-60 and 12-65 for NC-JT scheduled by DCI 12-45 and 12-55 and the PDSCH 12-70 not used for NC-JT scheduled by another DCI 12-50 (12-41). When multiple PDSCHs with the same priority are scheduled in overlapping time resources, the UE needs to decode all the PDSCHs. However, when multiple PDSCHs with different priorities are scheduled, the UE essentially needs to decode the PDSCH with the highest priority. When the UE cannot decode multiple PDSCHs scheduled in overlapping time resources, the base station may not schedule the PDSCHs with the same priority.

[0240] The following example may be considered as a method for determining the priority of a PDSCH not used for NC-JT.

[0241] 1) The UE and the base station can set different priorities according to the PDSCH scheduling information notification time. For example, the UE with a later PDSCH scheduling information notification time or a smaller K 0 The PDSCH with the value K can have a higher priority than the PDSCH in the opposite case. When the PDSCH for NC-JT and the PDSCH not used for NC-JT are mixed, the UE and the base station can use the PDSCH with the value K. 0 The minimum value among the values ​​determines the priority of PDSCH for NC-JT.

[0242] 2) The UE and the base station may set different priorities according to whether the PDSCH is a PDSCH for NC-JT. For example, when the PDSCH for NC-JT and the PDSCH not used for NC-JT are mixed, the PDSCH for NC-JT may have a higher priority than the PDSCH not used for NC-JT.

[0243] 3) The UE and the base station can set different priorities according to the scheme for scheduling PDSCH. For example, PDSCH dynamically scheduled via DCI etc. can have a higher priority than PDSCH scheduled semi-persistently (i.e., PDSCH scheduled according to a specified period configured via RRC).

[0244] 4) The UE and the base station can set different priorities according to whether the PDSCH is repeatedly transmitted. For example, when one PDSCH is repeated during multiple time slots and another PDSCH is not repeated, the non-repeated PDSCH can have a higher priority.

[0245] Two or more of the above examples may be implemented in combination as needed, and in addition to the above examples, similar methods for determining the priority of PDSCH may also be used. In addition, when the above examples are implemented in combination, the priorities of the various methods may be configured hierarchically. For example, PDSCH may be prioritized first according to method 3, then prioritized according to method 4 if there are PDSCHs with the same priority, then prioritized according to method 1 if there are still PDSCHs with the same priority, and then prioritized according to method 2 if there are PDSCHs with the same priority. Although the order of the prioritization methods may change, not all possibilities are listed to avoid confusing the subject matter of the present description.

[0246] The method for prioritizing PDSCHs scheduled in overlapping time resources according to an embodiment can be summarized as follows: Fig.13 Flowchart shown.

[0247] Fig.13 is a flow chart illustrating a method for prioritizing PDSCHs scheduled in overlapping time resources according to an embodiment of the present disclosure.

[0248] refer to Fig.13, the UE determines the number of PDSCHs allocated on the OFDM symbol (13-10). When the number of PDSCHs is 1, the UE receives the PDSCH (13-20). When the number of PDSCHs exceeds 1, the UE determines whether the NC-JT PDSCH is included in the PDSCH (13-30), wherein at least one or more of the methods in the aforementioned examples A to E may be used. Subsequently, the UE assigns a priority value to each PDSCH (13-40), wherein one or more of the methods in the aforementioned examples 1) to 4) may be used. When the NC-JT PDSCH is included (13-50), the same priority value is assigned to the NC-JT PDSCH (13-60), wherein the priority value of the NC-JT PDSCH may be different from the priority value of the non-NC-JT PDSCH. When the NC-JT PDSCH has the highest priority (13-65), the UE receives the NC-JT PDSCH (13-80); otherwise, the UE receives the PDSCH assigned the highest priority (13-90). When the NC-JT PDSCH is not included (13-50), the UE allocates different priority values ​​(13-70) to all PDSCHs and receives the PDSCH with the highest priority (13-90).

[0249] Third embodiment: Method for reducing complexity of UE supporting NC-JT

[0250] This embodiment provides various specific methods for reducing the reception complexity of a UE supporting NC-JT.

[0251] First, in multi-PDCCH based NC-JT, the DMRS of a specific PDSCH for NC-JT may overlap with another PDSCH for NC-JT on frequency-time resources. In this case, the decoding performance through DMRS decreases due to the interference of the overlapping PDSCH, and high UE reception complexity is required to overcome this decrease. In a method for reducing the reception complexity of a UE supporting NC-JT, the DMRS of the PDSCH for NC-JT can be configured not to overlap with another PDSCH for NC-JT on frequency-time resources. To this end, the following example can be considered.

[0252] a. When the PDSCHs transmitted in multi-PDCCH-based NC-JT overlap on frequency-time resources, the base station can match the starting position of the DMRS used for the PDSCH on the time resources, the length of the DMRS front-end symbol, the DMRS type, the number of additional DMRS symbols, and the position configuration of the additional DMRS symbols. In addition, the base station can configure the DMRS ports or CDM groups of the DMRSs of the various PDSCHs used for NC-JT not to overlap. Therefore, the base station and the UE can avoid the DMRS of the PDSCH used for NC-JT from overlapping with the DMRS or data of another PDSCH used for NC-JT. The UE does not expect the DMRS configuration of each PDSCH used for NC-JT to be different from the above configuration (i.e., the case where the DMRS of a specific PDSCH is configured to overlap with the DMRS or data of another PDSCH), thereby reducing the reception complexity of the UE.

[0253] An example of the above configuration that avoids overlap is as follows.

[0254] * The base station and UE can share the RRC configuration of DMRS for PDSCH mapping type A and PDSCH mapping type B for all PDSCHs of NC-JT, such as DMRS-type or maxLength (maximum number of DMRS start symbols), and the configuration can be included in PDSCH-Config, dmrs-DownlinkForPDSCH-MappingTypeA, dmrs-DownlinkForPDSCH-MappingTypeB or DMRS-DownlinkConfig in NR.

[0255] * Even if the PDSCH mapping type indicated by the DCI for each PDSCH is the same, and the offset and length of the symbols allocated by the PDSCH are the same or one or more of them are different, the base station and the UE can configure the starting symbol or additional symbols at which the DMRS of different PDSCHs are located to have the same position or not overlap with the data of different PDSCHs.

[0256] * The base station and the UE may configure the same number of DMRS front-loading symbols and the same number of DMRS CDM groups without data associated with the antenna port configuration indicated by the DCI for each PDSCH, and may configure a different CDM group for each antenna port.

[0257] For example, when DMRS-type = 1 and the maximum number of DMRS start symbols = 2, the limited DMRS port combinations in Table 7 including some antenna port configuration values ​​available in NR can be used for NC-JT. For example, the following details may apply.

[0258] * When two PDSCHs are scheduled for NC-JT, and the code points of the DMRS ports for these PDSCHs are 7 and 8 respectively, the number of DMRS front-load symbols and the number of DMRS CDM groups without data are the same, and the DMRS CDM groups are different. Therefore, the DMRS port is a DMRS port combination that can be allocated.

[0259] * When two PDSCHs are scheduled for NC-JT, and the code points of the DMRS ports for these PDSCHs are 12 and 13 respectively, the number of DMRS front-load symbols and the number of DMRS CDM groups without data are the same, and the DMRS CDM groups are the same. Therefore, the DMRS port is a DMRS port combination that cannot be allocated.

[0260] Although there are various other combinations that can / cannot be allocated, not all possibilities are listed so as not to obscure the subject matter of the present description. The DMRS port combinations and their code points that can be allocated to NC-JT can also be redefined.

[0261] [Table 7]

[0262]

[0263] Although there may be other configurations to prevent overlap between a PDSCH for NC-JT and a DMRS for another PDSCH for NC-JT, not all possibilities are listed to avoid confusing the subject matter of the present description.

[0264] b. When the PDSCHs transmitted in multi-PDCCH based NC-JT overlap in frequency-time resources, rate matching may be indicated so that the data of a particular PDSCH is prevented from overlapping with the DMRS of another PDSCH. For example, the base station may semi-statically configure a rate matching mode including the DMRS symbol positions of other PDSCHs, and may dynamically activate the mode by indicating the mode to the UE via DCI in NC-JT. Alternatively, the base station may configure the ZP-CSI-RS to include the DMRS symbol positions of other PDSCHs, and may apply the ZP-CSI-RS by semi-statically or dynamically indicating the ZP-CSI-RS via DCI.

[0265] Although there may be a variety of methods similar to the above examples, not all possibilities are listed in order not to obscure the subject matter of this description.

[0266] For a UE supporting NC-JT that supports both NC-JT and MU-MIMO, both interference cancellation between multiple PDSCHs sent via NC-JT or codewords and MU interference cancellation are required, thus requiring very high receiver complexity. NC-JT is effective when a transmission point is idle due to low network traffic, while MU-MIMO is effective when multiple UEs within a cell need to receive data simultaneously due to heavy network traffic. Therefore, it is unusual for NC-JT and MU-MIMO to be used at the same time, and the UE does not expect another UE in the cell to be scheduled at the same time in the OFDM symbol where the PDSCH for NC-JT is located, and does not expect the PDSCH for NC-JT to be scheduled in the OFDM symbol for simultaneous scheduling of multiple UEs, thereby significantly reducing the complexity of the UE.

[0267] A method for a UE to activate a receiver for only one of NC-JT and MU-MIMO at a specific time according to an embodiment can be summarized as Fig.14 Flowchart shown.

[0268] Fig.14 is a flowchart illustrating a method for a UE to activate a receiver for only one of NC-JT and MU-MIMO to reduce complexity according to an embodiment of the present disclosure.

[0269] refer to Fig.14 , the UE determines whether the NC-JT PDSCH is received (14-10). The process may be performed by a combination of one or more of the above examples a or b. Alternatively, in NC-JT based on a single PDCCH, the UE may determine whether the NC-JT PDSCH is received based on the number of beams indicated by the DCI (e.g., the number of TCI states indicated by the TCI code point). When the number of TCI states indicated by the TCI code point is 2 or more, the UE may determine that the NC-JT PDSCH is received. When the number of TCI states is 1, the UE may not determine that the NC-JT PDSCH is received.

[0270] When the NC-JT PDSCH is not received, the UE operates the MU receiver based on MU-MIMO to receive data (14-20). When the NC-JT PDSCH is received, the UE operates the NC-JT receiver to receive NC-JT data (14-30). This operation may mean that the UE eliminates interference in the allocated PDSCH by itself.

[0271] Fig.15 is a block diagram showing the structure of a UE according to an embodiment of the present disclosure.

[0272] refer to Fig.15, the UE may include a transceiver including a receiver 15-00 and a transmitter 15-10 and a controller 15-05 including a memory and a processor. The transceiver including the receiver 15-00 and the transmitter 15-10 and the controller 15-05 operate according to the aforementioned communication method of the UE. However, the components of the UE are not limited to the above examples. For example, the UE may include more components or fewer components than the aforementioned components. In addition, the transceivers 15-00 and 15-10 and the controller 15-05 may be configured as a single chip.

[0273] The transceiver including the receiver 15-00 and the transmitter 15-10 can send signals to and receive signals from the base station. Here, the signal may include control information and data. To this end, the transceiver including the receiver 15-00 and the transmitter 15-10 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal and an RF receiver for performing low noise amplification on the received signal and down-converting the frequency of the received signal. However, this is only an embodiment of the transceiver including the receiver 15-00 and the transmitter 15-10, and the components of the transceiver including the receiver 15-00 and the transmitter 15-10 are not limited to the RF transmitter and the RF receiver.

[0274] Furthermore, the transceiver including the receiver 15-00 and the transmitter 15-10 may receive a signal through a radio channel to output the signal to the controller 15-05, and may transmit a signal output from the controller 15-05 through the radio channel.

[0275] The controller 15-05 may store programs and data required for the operation of the UE. The controller 15-05 may be implemented as at least one processor. In addition, the controller 15-05 may store control information or data included in the signal obtained by the UE. The controller 15-05 may include a memory configured as a storage medium, such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a compact disk (CD)-ROM, and a digital video disk (DVD) or a combination of storage media.

[0276] The controller 15-05 may control a series of processes so that the UE may operate according to the aforementioned embodiments. According to some embodiments, the controller 15-05 may control the components of the UE to receive two layers of DCI, thereby receiving multiple PDSCHs simultaneously.

[0277] Fig.16 is a block diagram showing the structure of a base station according to an embodiment of the present disclosure.

[0278] refer to Fig.16, the base station may include a transceiver including a receiver 16-00 and a transmitter 16-10 and a controller 16-05 including a memory and a processor. The transceiver including the receiver 16-00 and the transmitter 16-10 and the controller 16-05 may operate according to the aforementioned communication method of the base station. However, the components of the base station are not limited to the aforementioned examples. For example, the base station may include more components or fewer components than the aforementioned components. In addition, the transceiver including the receiver 16-00 and the transmitter 16-10 and the controller 16-05 may be configured as a single chip.

[0279] The transceiver including the receiver 16-00 and the transmitter 16-10 can send signals to the UE and receive signals from the UE. Here, the signal may include control information and data. To this end, the transceiver including the receiver 16-00 and the transmitter 16-10 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal and an RF receiver for low-noise amplifying the received signal and down-converting the frequency of the received signal. However, this is only an embodiment of the transceiver including the receiver 16-00 and the transmitter 16-10, and the components of the transceiver including the receiver 16-00 and the transmitter 16-10 are not limited to the RF transmitter and the RF receiver.

[0280] Furthermore, the transceiver including the receiver 16 - 00 and the transmitter 16 - 10 may receive a signal through a radio channel to output the signal to the controller 16 - 05, and may transmit a signal output from the controller 16 - 05 through the radio channel.

[0281] The controller 16-05 may store programs and data required for the base station operation. The controller 16-05 may be implemented as at least one processor. In addition, the controller 16-05 may store control information or data included in the signal obtained by the base station. The controller 16-05 may include a memory configured as a storage medium, such as a ROM, RAM, hard disk, CD-ROM and DVD, or a combination of storage media.

[0282] The controller 16-05 may control a series of processes so that the base station may operate according to the aforementioned embodiments.According to some embodiments, the controller 16-05 may control each component of the base station to configure a two-layer DCI including allocation information on multiple PDSCHs and transmit the DCI.

[0283] Although the present disclosure has been shown and described with reference to its various embodiments, it will be appreciated by those skilled in the art that various changes may be made in form and detail without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. In addition, if necessary, the above-mentioned various embodiments may be combined. For example, any number of any embodiments of the present disclosure may be combined to operate a base station and a terminal.

Claims

1. A method performed by a terminal in a communication system, the method comprising: Receiving first downlink control information DCI for scheduling a first physical downlink shared channel PDSCH from a first transmission / reception point TRP; receiving, from a second TRP, a second DCI for scheduling a second PDSCH; receiving the first PDSCH from the first TRP based on a first PDSCH demodulation reference signal DMRS for the first PDSCH; as well as receiving the second PDSCH from the second TRP based on a second PDSCH DMRS for the second PDSCH, Wherein, in a case where the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH overlap in whole or in part in the time-frequency domain, wherein: The number of frontload DMRS symbols in the first DMRS configuration is the same as the number of frontload DMRS symbols in the second DMRS configuration; The number of additional DMRS symbols in the first DMRS configuration is the same as the number of additional DMRS symbols in the second DMRS configuration; The DMRS symbol position in the first DMRS configuration is the same as the DMRS symbol position in the second DMRS configuration; and The DMRS configuration type in the first DMRS configuration is the same as the DMRS configuration type in the second DMRS configuration.

2. The method according to claim 1, wherein: The first DCI includes a first antenna port field for the first PDSCH DMRS, The second DCI includes a second antenna port field for the second PDSCH DMRS, wherein, in a case where the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH are decoded according to the same priority, and The antenna port indicated by the first antenna port field does not overlap with the antenna port indicated by the second antenna port field.

3. The method according to claim 1, wherein: The code division multiplexing (CDM) group of the first PDSCH DMRS is different from the CDM group of the second PDSCH DMRS.

4. The method according to claim 1, wherein: The first PDSCH and the second PDSCH are non-coherent joint transmission NC-JT PDSCHs including data transmission, and Wherein, in the case where the NC-JT PDSCH is not received, the terminal is configured to operate a multi-user MU receiver to receive data based on MU multiple-input multiple-output MU-MIMO, wherein, upon receiving the NC-JT PDSCH, the terminal is configured to operate an NC-JT receiver to receive data on the NC-JT PDSCH, and The terminal is configured to activate one of the MU receiver or the NC-JT receiver at the same time.

5. A method performed by a base station in a communication system, the method comprising: Sending first downlink control information DCI for scheduling a first physical downlink shared channel PDSCH to the terminal based on a first transmitting and receiving point TRP of the base station; as well as Sending a second DCI for scheduling a second PDSCH to the terminal based on a second TRP of the base station; Sending the first PDSCH and a first PDSCH demodulation reference signal DMRS for the first PDSCH to the terminal based on the first TRP; and Sending the second PDSCH and a second PDSCH DMRS for the second PDSCH to the terminal based on the second TRP, Wherein, in a case where the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH overlap in whole or in part in the time-frequency domain, wherein: The number of frontload DMRS symbols in the first DMRS configuration is the same as the number of frontload DMRS symbols in the second DMRS configuration; The number of additional DMRS symbols in the first DMRS configuration is the same as the number of additional DMRS symbols in the second DMRS configuration; The DMRS symbol position in the first DMRS configuration is the same as the DMRS symbol position in the second DMRS configuration; and The DMRS configuration type in the first DMRS configuration is the same as the DMRS configuration type in the second DMRS configuration.

6. The method according to claim 5, wherein: The first DCI includes a first antenna port field for the first PDSCH DMRS, The second DCI includes a second antenna port field for the second PDSCH DMRS, wherein, in a case where the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH are decoded according to the same priority, and The antenna port indicated by the first antenna port field does not overlap with the antenna port indicated by the second antenna port field.

7. The method according to claim 5, wherein: The code division multiplexing (CDM) group of the first PDSCH DMRS is different from the CDM group of the second PDSCH DMRS.

8. A user equipment UE in a communication system, the UE comprising: Transceiver; and A processor, coupled to the transceiver, is configured to: Receiving first downlink control information DCI for scheduling a first physical downlink shared channel PDSCH from a first transmission / reception point TRP; receiving, from a second TRP, a second DCI for scheduling a second PDSCH; receiving the first PDSCH from the first TRP based on a first PDSCH demodulation reference signal DMRS for the first PDSCH; and receiving the second PDSCH from the second TRP based on a second PDSCH DMRS for the second PDSCH, Wherein, in a case where the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH overlap in whole or in part in the time-frequency domain, wherein: The number of frontload DMRS symbols in the first DMRS configuration is the same as the number of frontload DMRS symbols in the second DMRS configuration; The number of additional DMRS symbols in the first DMRS configuration is the same as the number of additional DMRS symbols in the second DMRS configuration; The DMRS symbol position in the first DMRS configuration is the same as the DMRS symbol position in the second DMRS configuration; and The DMRS configuration type in the first DMRS configuration is the same as the DMRS configuration type in the second DMRS configuration.

9. The UE according to claim 8, wherein: The first DCI includes a first antenna port field for the first PDSCH DMRS, The second DCI includes a second antenna port field for the second PDSCH DMRS, wherein, in a case where the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH are decoded according to the same priority, and The antenna port indicated by the first antenna port field does not overlap with the antenna port indicated by the second antenna port field.

10. The UE according to claim 8, wherein: The code division multiplexing (CDM) group of the first PDSCH DMRS is different from the CDM group of the second PDSCH DMRS.

11. The UE according to claim 8, wherein: The first PDSCH and the second PDSCH are non-coherent joint transmission NC-JT PDSCHs including data transmission, and Wherein, in the case where the NC-JT PDSCH is not received, the terminal is configured to operate a multi-user MU receiver to receive data based on MU multiple-input multiple-output MU-MIMO, wherein, upon receiving the NC-JT PDSCH, the terminal is configured to operate an NC-JT receiver to receive data on the NC-JT PDSCH, and The terminal is configured to activate one of the MU receiver or the NC-JT receiver at the same time.

12. A base station in a communication system, the base station comprising: Transceiver; and A processor, coupled to the transceiver, is configured to: Sending first downlink control information DCI for scheduling a first physical downlink shared channel PDSCH to the terminal based on a first transmitting and receiving point TRP of the base station; Sending a second DCI for scheduling a second PDSCH to the terminal based on a second TRP of the base station; Sending the first PDSCH and a first PDSCH demodulation reference signal DMRS for the first PDSCH to the terminal based on the first TRP; and Sending the second PDSCH and a second PDSCH DMRS for the second PDSCH to the terminal based on the second TRP, Wherein, in a case where the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH overlap in whole or in part in the time-frequency domain, wherein: The number of frontload DMRS symbols in the first DMRS configuration is the same as the number of frontload DMRS symbols in the second DMRS configuration; The number of additional DMRS symbols in the first DMRS configuration is the same as the number of additional DMRS symbols in the second DMRS configuration; The DMRS symbol position in the first DMRS configuration is the same as the DMRS symbol position in the second DMRS configuration; and The DMRS configuration type in the first DMRS configuration is the same as the DMRS configuration type in the second DMRS configuration.

13. The base station according to claim 12, wherein: The first DCI includes a first antenna port field for the first PDSCH DMRS, The second DCI includes a second antenna port field for the second PDSCH DMRS, wherein, in a case where the first TRP and the second TRP are configured for multi-TRP-based data transmission, the first PDSCH and the second PDSCH are decoded according to the same priority, and The antenna port indicated by the first antenna port field does not overlap with the antenna port indicated by the second antenna port field.

14. The base station according to claim 12, wherein: The code division multiplexing (CDM) group of the first PDSCH DMRS is different from the CDM group of the second PDSCH DMRS.

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