Method and device for sending and receiving multiple data in a wireless cooperative communication system

Abstract

The present disclosure relates to: a communication technology for integrating a fifth generation (5G) or pre-5G communication system with IoT technology to support a higher data transmission rate than a fourth generation (4G) communication system (such as long term evolution (LTE)); and a system. The present disclosure can be applied to smart services (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail business, security and safety-related services, etc.) based on 5G communication technology and IoT-related technologies. According to various embodiments of the present invention, a method and apparatus for sending and receiving multiple data in a wireless cooperative communication system can be provided.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication network, and more particularly, to a method and apparatus for transmitting and receiving a plurality of data in a wireless cooperative communication system. Background Art

[0002] 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, also known as "beyond 4G network" communication systems or "post-Long Term Evolution (LTE)" systems. 5G communication systems are believed to be implemented in a higher frequency millimeter wave (mmWave) band of about sixty gigahertz (60 GHz) in order to achieve higher data rates.

[0003] In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), full-dimensional multiple-input multiple-output (FD-MIMO), array antennas, analog beamforming, and massive antenna technology have been discussed in 5G communication systems. In addition, system network improvements are being developed based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, cooperative communications, coordinated multi-point (CoMP), receiving-end interference cancellation, etc. In 5G systems, hybrid frequency shift keying (FSK) and quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA) as advanced access technologies are also being developed.

[0004] The Internet is a human-centered connected network in which humans generate and consume information. The Internet is now developing towards 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, which is a combination of IoE technology and big data processing technology through connection with cloud servers. As IoT implementation requires technical elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology and security technology, sensor networks, machine-to-machine (M2M) communication, machine type communication (MTC), etc. have been studied recently. Such an IoT environment can provide intelligent Internet technology services to 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] Accordingly, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, MTC, and M2M communications can be implemented through beamforming, MIMO, and array antennas. Cloud RAN as an application of the above-mentioned big data processing technology can also be considered as a fusion of 5G technology and IoT technology.

[0006] With the development of wireless communication systems as described above, there is a need in the art for a data transmission / reception scheme for network cooperative communication. Summary of the invention

[0007] Technical issues

[0008] Based on the foregoing discussion, the present disclosure provides a method and apparatus for transmitting and receiving one or more data between a transmission node and a UE to perform cooperative communication in a wireless communication system.

[0009] The technical subject matter pursued in the present disclosure may not be limited to the above-mentioned technical subject matter, and other technical subject matter not mentioned may be clearly understood by those skilled in the art to which the present disclosure belongs through the following description.

[0010] Technical Solution

[0011] According to an embodiment of the present disclosure, an operation method of a base station in a wireless communication system may include a method of instructing to send multiple transport blocks (TBs) and downlink control information (DCI) to support cooperative communication.

[0012] In order to solve the aforementioned problem, the method performed by a terminal in a wireless communication system according to an embodiment of the present disclosure may include: receiving control information from a base station; based on the control information, identifying whether an initial transmission signal or a retransmission signal is sent from at least one transmission reception point (TRP); and when identifying that a retransmission signal is sent, receiving a retransmission signal from the at least one TRP.

[0013] The control information may include at least one of demodulation reference signal (DMRS) port information, modulation and coding scheme (MCS) information, a new data indicator (NDI), code block group transmission information (CBGTI), and code block group flushing-out information (CBGFI).

[0014] The receiving of the retransmission signal may include receiving the retransmission signal from a first TRP that transmits an initial transmission signal corresponding to the retransmission signal and a second TRP that does not transmit the initial transmission signal corresponding to the retransmission signal.

[0015] Receipt of the retransmission signal may include receiving all or some of the retransmission signal from a TRP that did not send an initial transmission signal corresponding to the retransmission signal.

[0016] Receiving the retransmission signal may include receiving a portion of the retransmission signal from a first TRP that sends an initial transmission signal corresponding to the retransmission signal, and receiving the remaining retransmission signal from a second TRP that does not send the initial transmission signal corresponding to the retransmission signal.

[0017] The retransmission signal may be mapped to the same codeword and sent from at least one TRP.

[0018] In order to solve the aforementioned problem, the method performed by the base station in the wireless communication system according to the embodiment may include: generating control information for identifying whether an initial transmission signal or a retransmission signal is sent from at least one transmit receive point (TRP); sending the control information to the terminal; and in a case where the control information indicates that a retransmission signal is sent, sending the retransmission signal to the terminal via at least one TRP.

[0019] The sending of the retransmission signal may include sending the retransmission signal to the terminal via a first TRP that sends an initial transmission signal corresponding to the retransmission signal and a second TRP that does not send the initial transmission signal corresponding to the retransmission signal.

[0020] The sending of the retransmission signal may include sending all or some of the retransmission signals to the terminal via a TRP that does not send an initial transmission signal corresponding to the retransmission signal.

[0021] The sending of the retransmission signal may include sending a portion of the retransmission signal to the terminal via a first TRP that sends an initial transmission signal corresponding to the retransmission signal, and sending the remaining retransmission signal to the terminal via a second TRP that does not send the initial transmission signal corresponding to the retransmission signal.

[0022] In order to solve the aforementioned problems, a terminal in a wireless communication system according to an embodiment may include: a transceiver; and a controller, configured to receive control information from a base station through the transceiver, identify whether an initial transmission signal or a retransmission signal is sent from at least one transmit receive point (TRP) based on the control information, and receive the retransmission signal from at least one TRP through the transceiver when it is identified that the retransmission signal is sent.

[0023] In order to solve the aforementioned problems, according to an embodiment, a base station in a wireless communication system may include: a transceiver; and a controller, configured to generate control information for identifying whether an initial transmission signal or a retransmission signal is sent from at least one transmit receive point (TRP), send the control information to a terminal through the transceiver, and when the control information indicates that a retransmission signal is sent, send the retransmission signal to the terminal via at least one TRP.

[0024] Beneficial Effects

[0025] According to an embodiment of the present disclosure, a method and an apparatus for transmitting and receiving one or more data between a transmission node and a UE in a wireless communication system to perform cooperative communication may be provided.

[0026] Advantageous effects obtained from the present disclosure may not be limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those skilled in the art to which the present disclosure belongs through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A transmission structure in the time-frequency domain in a Long Term Evolution (LTE) or Evolved Universal Terrestrial Radio Access (E-UTRA) system, an LTE-Advanced (LTE-A) system, an NR system, or a similar wireless communication system according to an embodiment is shown;

[0028] Figure 2 shows the structure of frames, subframes, and time slots in the fifth generation (5G) according to an embodiment;

[0029] Figure 3shows a configuration of a bandwidth part (BWP) in a wireless communication system according to an embodiment;

[0030] Figure 4 Indicating and changing a BWP in a wireless communication system according to an embodiment is shown;

[0031] Figure 5 Configuring a control region for a downlink control channel in a wireless communication system according to an embodiment is shown;

[0032] Figure 6 An example of physical downlink shared channel (PDSCH) frequency domain resource allocation in a wireless communication system according to an embodiment is shown;

[0033] Figure 7 An example of PDSCH time domain resource allocation in a wireless communication system according to an embodiment is shown;

[0034] Figure 8 An example of time domain resource allocation according to a subcarrier spacing of a data channel and a subcarrier spacing of a control channel in a wireless communication system according to an embodiment is shown;

[0035] Fig. 9 shows a cooperative communication antenna port configuration according to an embodiment;

[0036] Fig.10 shows cooperative communication based on two codewords according to an embodiment;

[0037] Fig.11 shows cooperative communication based on two codewords according to other embodiments;

[0038] Fig.12 shows cooperative communication based on two codewords according to other embodiments;

[0039] Fig.13 shows a structure of a UE in a wireless communication system according to an embodiment; and

[0040] Fig.14 The structure of a base station in a wireless communication system according to an embodiment is shown. DETAILED DESCRIPTION

[0041] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0042] When describing the embodiments of the present disclosure, descriptions related to technical contents known in the art and not directly related to the present disclosure will be omitted. Such omission of unnecessary descriptions is intended to prevent the main concept of the present disclosure from being obscured and to convey the main concept more clearly.

[0043] For the same reason, in the drawings, some elements may be exaggerated, omitted or schematically shown. The size of each element does not fully reflect the actual size. In the drawings, the same or corresponding elements have the same reference numerals.

[0044] By referring to the embodiments described in detail below in conjunction with the accompanying drawings, the advantages and features of the present disclosure and the modes for achieving them will become apparent. However, the present disclosure is not limited to the embodiments set forth below, but can be implemented in various different forms. The following embodiments are provided only to fully disclose the present disclosure and inform those skilled in the art of the scope of the present disclosure. Throughout the specification, the same or similar reference numerals represent the same or similar elements.

[0045] It will be understood herein that each block of the flowchart diagram and the combination of blocks in the flowchart diagram 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 organization to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device create a device for implementing the functions specified in the (multiple) flowchart blocks. These computer program instructions can also be stored in a computer-usable or computer-readable memory, which can instruct the computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-usable or computer-readable memory produce an article including an instruction device, which implements the functions specified in the flowchart block. The computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are performed on the computer or other programmable device, thereby generating 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 (multiple) flowchart blocks.

[0046] In addition, each block of the flowchart diagram may represent a module, a code segment, or a code portion, which includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions mentioned in the blocks may not occur 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.

[0047] "Unit" used herein 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, a unit does not always have the meaning of being limited to software or hardware. A unit can be constructed to be stored in an addressable storage medium or to execute one or more processors. Therefore, a unit includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, attributes, processes, subroutines, program code segments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays and parameters. The elements and functions provided by the unit can be combined into fewer elements or units, or divided into more elements or units. In addition, elements and units may be implemented as one or more CPUs in a reproduction device or a secure multimedia card. The unit in the embodiment may include one or more processors.

[0048] 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 description may make the subject matter of the present disclosure unnecessary unclear, the detailed description of the known functions or configurations incorporated herein will be omitted. The terms to be described below are terms defined in consideration of the functions in the present disclosure, and may differ according to the user, the user's intention or habit. Therefore, the definition of the terms should be based on the content of the entire specification. In the following description, a base station is an entity that allocates resources to a terminal, and may be at least one of a gNODE B (gNB), an eNODE B (eNB), a node B, a base station (BS), a wireless access unit, a base station controller, and a node on a network. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, "downlink" refers to a radio link via which a base station sends a signal to a terminal, and "uplink" refers to a radio link via which a terminal sends a signal to a base station. Of course, the examples of base stations and terminals are not limited thereto. The following description of the present disclosure relates to a technology for receiving broadcast information from a base station by a terminal in a wireless communication system. The present disclosure relates to a communication technology and a system thereof for integrating IoT technology with a 5G communication system, wherein the 5G communication system is designed to support a higher data transmission rate than a 4G system. The present disclosure can be applied to smart services (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail business, security and safety related services, etc.) based on 5G communication technology and IoT related technology.

[0049] In the following description, for example, for convenience, terms related to broadcast information, control information, communication coverage, state change (e.g., event), network entity, message, device element, etc. are illustratively used. Therefore, the present disclosure is not limited to the terms used below, and other terms related to subjects with equivalent technical meanings may be used.

[0050] In the following description, for convenience of description, some terms and names defined in the 3rd Generation Partnership Project LTE (3GPP LTE) standard may be used. However, the present disclosure is not limited to these terms and names and can be applied to systems conforming to other standards.

[0051] 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 3GPP's high speed packet access (HSPA), LTE or Evolved Universal Terrestrial Radio Access (E-UTRA), LTE-Advanced (LTE-A) or LTE-Pro, 3GPP2's high rate packet data (HRPD) or ultra-mobile broadband (UMB), and IEEE 802.16e.

[0052] 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). UL refers to a radio link in which a user equipment (UE) or a mobile station (MS) sends data or a control signal to an eNode B or a base station (BS), and downlink refers to a radio link in which an eNode B sends data or a control signal to a UE. These multiple access schemes allocate and manage time-frequency resources for carrying data or control information for each user so that they do not overlap with each other, i.e., are orthogonal to each other, thereby dividing the data or control information for each user.

[0053] The post-LTE communication system, i.e., the 5G communication system, needs to be able to freely reflect various demands from users and service providers, and therefore needs to support services that meet various demands such as enhanced mobile broadband (eMBB), massive machine-type communication (mMTC), and ultra-reliable low-latency communication (URLLC).

[0054] eMBB is designed to provide data rates that are further enhanced than those supported by 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 gigabits per second (Gbps) in DL and a peak data rate of 10Gbps in UL. In addition, eMBB needs to provide a higher user-perceived data rate. To meet these requirements, improved transmission and reception technologies, including enhanced MIMO transmission technologies, are required. In addition, the data rate required by the 5G communication system can be met by adopting a frequency bandwidth wider than 20 megahertz (MHz) in a 3 to 6 GHz or 6 GHz frequency band or higher to replace the 2 GHz band currently used for LTE.

[0055] In the 5G communication system, mMTC is considered to support application services such as IoT. In order to effectively provide IoT, mMTC may require, for example, support for access of a large number of UEs in a cell, enhanced UE coverage, increased battery time, and reduced UE cost. IoT is connected 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 a cell, such as the basement of a building, and therefore may require wider coverage than other services provided by the 5G communication system. mMTC-enabled UEs need to be configured as low-cost UEs, and may require very long battery life, as it is difficult to frequently replace the UE's battery.

[0056] Finally, URLLC is a mission-critical cellular-based wireless communication service, such as remote control of robots or machinery, industrial automation, drones, remote healthcare, and emergency alerts, which requires ultra-low latency and ultra-reliable communications. URLLC-enabled services not only need to meet air interface latency of less than 0.5 milliseconds, but also need to have 10 -5Or lower packet error rate. Therefore, for services supporting URLLC, the 5G system needs to provide a shorter transmission time interval (TTI) than other services, and also needs a design for allocating wide resources in the frequency band. The aforementioned mMTC, URLLC and eMBB are merely examples of different service types, and the service types applied by the present disclosure are not limited to the aforementioned examples.

[0057] The aforementioned services considered in the 5G communication system need to be provided in a fusion manner with each other on the basis of a framework. That is, for efficient resource management and control, it is preferred that the services are controlled and transmitted as an integrated system rather than operated independently.

[0058] Although the embodiments are described herein 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. Without departing from the scope of the present disclosure determined by those skilled in the art, these embodiments may also be applied to other communication systems with some modifications.

[0059] The present disclosure relates to a method and apparatus for repeatedly transmitting data and control signals between a plurality of transmission nodes and a UE performing cooperative communication to improve communication reliability.

[0060] According to the present disclosure, when network cooperative communication is used in a wireless communication system, the reliability of data / control signals received by a UE can be improved.

[0061] Hereinafter, the frame structure of the 5G system will be described in detail with reference to the accompanying drawings.

[0062] Figure 1 A transmission structure in the time-frequency domain in an LTE system, an LTE-A system, an NR system, or a similar wireless communication system according to an embodiment is shown.

[0063] Figure 1 The basic structure of the time-frequency domain is shown, which is the radio resource area for transmitting data or control channels in the 5G system. Figure 1 In the time-frequency domain, 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) 101, which can be defined by an OFDM symbol 102 on the time axis and a subcarrier 103 on the frequency axis. In the frequency domain, (For example, 12) consecutive REs may form a resource block (RB) 104 .

[0064] Figure 2The structure of frames, subframes, and time slots in 5G according to an embodiment is shown.

[0065] Figure 2 The time slot structure considered in the 5G system is shown. Figure 2 An example of the structure of a frame 200, a subframe 201, and a time slot 202 is shown. One frame 200 may be defined as 10 milliseconds (ms). One subframe 201 may be defined as 1 ms. Thus, one frame 200 may include a total of ten subframes 201 (0 to 9). One time slot 202 and 203 may be defined as 14 OFDM symbols (i.e., the number of symbols per time slot). ). A subframe 201 may include one or more time slots 202 and 203 as shown, and the number of time slots 202 and 203 in each subframe 201 may vary according to the set subcarrier spacing values ​​μ 204 and 205. Figure 2 In the example of , the subcarrier spacing values ​​are set to μ = 0 (204) and μ = 1 (205). When μ = 0 (204), a subframe 201 may include one time slot 202; when μ = 1 (205), a subframe 201 may include two time slots 203. That is, the number of time slots in each subframe is The number of time slots per frame can vary depending on the subcarrier spacing value μ set. Can vary accordingly. and The μ may be set according to each subcarrier spacing as defined in Table 1 below.

[0066] Table 1

[0067]

[0068] In NR, a component carrier (CC) or serving cell can 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 (BWP) 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 CORESET#0 or the common search space (CSS). Subsequently, the base station can configure the first BWP for the UE through RRC signaling, and can report at least one BWP configuration information, which can be indicated in the future through downlink control information (DCI). The base station can report the BWPID through DCI, thereby indicating to the UE the frequency band to be used by the UE. When the UE fails to receive the DCI in the currently allocated BWP for a specified time or longer, the UE can return to the default BWP and can attempt to receive the DCI.

[0069] Figure 3 A BWP configuration in a wireless communication system according to an embodiment is shown.

[0070] Figure 3 An example of the configuration of a BWP in a 5G communication system is shown. Figure 3 , shows an example, where the UE bandwidth 300 includes two BWPs, namely, BWP#1 305 and BWP#2 310. The base station may configure one BWP or multiple BWPs for the UE, and may configure information about each BWP, as shown in Table 2.

[0071] Table 2

[0072]

[0073] In addition to the configuration information shown in Table 2, various parameters related to BWP can be configured for the UE. The aforementioned information can be sent from the base station to the UE through higher layer signaling (such as RRC signaling). One configured BWP or at least one of multiple configured BWPs can be activated. Whether to activate the configured BWP can be semi-statically indicated to the UE from the base station through RRC signaling, or dynamically indicated to the UE through a medium access control (MAC) control element (CE) or DCI.

[0074] Configuration of the BWP supported by the 5G communication system can be used for various purposes.

[0075] In one example, when the bandwidth supported by the UE is less than the system bandwidth, the bandwidth can be supported by configuring the BWP. For example, the frequency position of the BWP in Table 2 (configuration information 2) can be set for the UE so that the UE can send and receive data at a specific frequency position within the system bandwidth.

[0076] Optionally, the base station can configure multiple BWPs for the UE to support different numerologies. For example, to support random UEs using both 15kHz subcarrier spacing and 30kHz subcarrier spacing for data transmission and reception, two BWPs can be configured to use 15kHz subcarrier spacing and 30kHz subcarrier spacing, respectively. Different BWPs can be frequency-division multiplexed (FDM). When the UE intends to send and receive data with a specific subcarrier spacing, the BWP configured with the subcarrier spacing can be activated.

[0077] The base station can also configure a BWP with different bandwidths for the UE in order to reduce the power consumption of the UE. For example, when the UE supports a very large bandwidth, such as a bandwidth of 100 MHz, and always sends and receives data within this bandwidth, the UE may consume a lot of power. In particular, even when there is no business, the UE unnecessarily monitors the downlink control channel on a large bandwidth of 100 MHz, which is very inefficient in terms of power consumption. Therefore, in order to reduce the power consumption of the UE, the base station can configure a BWP with a relatively small bandwidth of 20 MHz for the UE. In the absence of business, the UE can perform monitoring operations in the 20 MHz BWP, and when data is generated, it can use the 100 MHz bandwidth to send and receive data according to instructions from the base station.

[0078] Figure 4 Indicating and changing a BWP in a wireless communication system according to an embodiment is shown.

[0079] Figure 4 shows a method for dynamically changing the BWP configuration. Figure 4 , as described 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 to the UE as the configuration of each BWP. Figure 4 An example is shown in which two BWPs are configured in the UE bandwidth 400 of one UE, namely, BPW#1 405 and BWP#2 410. One or more configured BWPs may be activated, and Figure 4 An example of a BWP being activated is shown. Figure 4In the embodiment, BWP#1 402 of the configured BWP is activated in time slot #0 425, and the UE can monitor the physical downlink control channel (PDCCH) in the control region 1 445 configured in BWP#1 405, and can send and receive data 455 in BWP#1 405. The control region in which the UE receives the PDCCH may vary depending on which BWP is activated among the configured BWPs, and thus the bandwidth in which the UE monitors the PDCCH may vary.

[0080] 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 configuration changed according to the configuration switching indicator at a specific time, and may monitor the PDCCH in the control region configured in the activated BWP.

[0081] exist Figure 4 In the example, the base station may send a configuration switching indicator 415 to the UE in time slot #1 430, which indicates that the activated BWP is switched from the existing BWP #1 405 to BWP #2 410. After receiving the indicator, the UE may activate BWP #2 410 according to the content of the indicator. A transition time 420 for BWP switching may be required, and the time to switch and apply the BWP to be activated may be determined accordingly. Figure 4 In the example, after receiving the configuration switching indicator 415, a switching time 420 of one time slot is required. Data transmission and reception may not be performed (460) during the switching time 420. Therefore, BWP #2 410 may be activated in time slot #2 435, and thus operations of transmitting and receiving a control channel 450 and data 455 via the BWP may be performed.

[0082] The base station may pre-configure one BWP or multiple BWPs for the UE via higher layer signaling (eg, RRC signaling), and may indicate activation by mapping the configuration switch indicator 415 with one of the BWP configurations pre-configured by the base station. 2 The N-bit indicator may indicate one BWP selected from N pre-configured BWPs. Table 3 shows an example of using a two-bit indicator to indicate configuration information about a BWP.

[0083] Table 3

[0084] Indicator value BWP Configuration 00 Bandwidth configuration configured via higher layer signaling A 01 Bandwidth configuration configured via higher layer signaling B 10 Bandwidth configuration configured via higher layer signaling C 11 Bandwidth configuration configured via higher layer signaling D

[0085] The configuration switching indicator 415 of the BWP shown in Table 4 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).

[0086] The time to apply BWP activation according to the aforementioned configuration switching indicator 415 of the BWP shown in Table 4 may depend on the following factors. The time to apply the configuration switch may depend on a predefined value (e.g., applying the configuration switch after N (≥1) time slots since the configuration switch indicator was received), which may be set by the base station for the UE via higher layer signaling (e.g., RRC signaling), or may be sent via the configuration switch indicator 415. In addition, the time to apply the configuration switch may be determined by combining the above methods. After receiving the configuration switch indicator 415 for the BWP, the UE may apply the switched configuration according to the time obtained by the above method.

[0087] Hereinafter, a downlink control channel in a 5G communication system will be described in detail with reference to the accompanying drawings.

[0088] Figure 5 It is shown that a control region is configured for a downlink control channel in a wireless communication system according to an embodiment.

[0089] Figure 5 A control resource set (CORESET) for transmitting a downlink control channel in a 5G wireless communication system is shown. Figure 5 An example is shown in which a UE BWP 510 is configured on the frequency axis and two control resource sets (control resource set #1 (CORESET#1) 501 and control resource set #2 (CORESET#2) 502) are configured in one time slot 520 on the time axis. The control resource sets 501 and 502 may be configured in a specific frequency resource 503 in the entire UE BWP 510 on the frequency axis. The control resource sets 501 and 502 may be configured with one or more OFDM symbols on the time axis, which may be defined as a control region set duration 504. Figure 5 In the example of FIG. 5 , control resource set #1 501 is configured with a control resource set duration of two symbols, and control resource set #2 502 is configured with a control resource set duration of one symbol.

[0090] The control resource set (ControlResourceSet) in the above 5G can be configured for the UE by the base station through higher layer signaling (e.g., system information, master information block (MIB) or radio resource control (RRC) signaling). Configuring the control resource set for the UE indicates providing the UE with information such as the identifier of the control resource set, the frequency position of the control resource set, and the symbol duration of the control resource set. For example, multiple pieces of information shown in Table 4 below may be included.

[0091] Table 4

[0092]

[0093]

[0094] In Table 4, the tci-StatesPDCCH (abbreviated as TCI state) configuration information may include information about the index of one or more synchronization signal (synchronization signal, SS) / physical broadcast channel (physical broadcast channel, PBCH) blocks that are quasi co-located (quasi co-located, QCL) with the index of the demodulation reference signal (DMRS) or channel state information reference signal (CSI-RS) sent in the control resource set.

[0095] Hereinafter, a method for allocating time and frequency resources for data transmission in NR will be described.

[0096] In addition to the frequency-domain resource candidate allocations indicated by the BWP, NR can also provide the following specific frequency-domain resource allocations (FD-RA).

[0097] Figure 6 An example of PDSCH frequency domain resource allocation (RA) in a wireless communication system according to an embodiment is shown.

[0098] Figure 6 Three frequency domain resource allocation methods are shown, which are Type 0 600, Type 1 605, and dynamic switching 610 that can be configured by higher layers in NR.

[0099] refer to Figure 6, when the UE is configured to use only resource type 0 by higher layer signaling (600), some downlink control information (DCI) for allocating PDSCH to the UE has a bitmap of NRBG bit, and its condition will be described later. Here, NRBG represents the number of resource block groups (RBGs) determined according to the BWP size allocated by the BWP indicator and the higher layer parameter rbg-Size as in Table 5 and the RBG phase indicated by 1 indicated by the bitmap, and data is transmitted on the RBG indicated by 1 according to the bitmap.

[0100] Table 5

[0101] Bandwidth portion size Configuration 1 Configuration 2 1-36 2 4 37-72 4 8 73-144 8 16 145-275 16 16

[0102] When the UE is configured to use only resource type 1 through higher layer signaling (605), some DCIs used to allocate PDSCH to the UE have The base station can configure the starting virtual resource block (VRB) 620 and the length 625 of the frequency domain resources continuously allocated therefrom through the information.

[0103] When the UE is configured to use both resource type 0 and resource type 1 through higher layer signaling (610), some DCIs for allocating PDSCH to the UE have frequency domain resource allocation information 635 with the maximum value of the bit in the payload 615 for configuring resource type 0 and the payloads 620 and 625 for configuring resource type 1, which will be described later. One bit may be added to the most significant bit (MSB) of the frequency domain resource allocation information of the DCI, where a bit equal to 0 may indicate the use of resource type 0, and a bit equal to 1 may indicate the use of resource type 1.

[0104] Figure 7 An example of physical downlink shared channel (PDSCH) time domain resource allocation in a wireless communication system according to an embodiment is shown.

[0105] Figure 7 An example of time domain resource allocation in NR is shown. Figure 7 The base station can indicate the time domain location of the PDSCH resource according to the starting position 700 and length 705 of the OFDM symbol in the time slot, which is obtained by using a higher layer, scheduling offset (K 0 ) value and the subcarrier spacing (μ) of the data channel and control channel configured by DCI PDSCH , μ PDCCH ) to indicate dynamically.

[0106] Figure 8An example of time domain resource allocation according to a subcarrier spacing of a data channel and a subcarrier spacing of a control channel in a wireless communication system according to an embodiment is shown.

[0107] refer to Figure 8 , when the data channel and the control channel have the same subcarrier spacing (800, μ PDSCH =μ PDCCH ), since the number of data time slots and the number of control time slots are the same, the base station and the UE recognize that the predetermined time slot offset K 0 Scheduling offset occurs. When the subcarrier spacing of the data channel is different from the subcarrier spacing of the control channel (805, μ PDSCH ≠μ PDCCH ), since the number of data time slots and the number of control time slots are different, the base station and the UE identify the subcarrier spacing according to the predetermined time slot offset K based on the PDCCH 0 A scheduling drift has occurred.

[0108] In NR, for effective control channel reception of UE, the following various types of DCI formats as shown in Table 6 are provided according to the purpose.

[0109] Table 6

[0110]

[0111] For example, the base station may use DCI format 1_0 or DCI format 1_1 to schedule a PDSCH for one cell.

[0112] 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, DCI format 1_1 includes at least the following information.

[0113] - Identifier of DCI format (1 bit): DCI format indicator, which can be set to 1.

[0114] - 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 shown in the aforementioned frequency domain resource allocation.

[0115] - Time domain resource allocation (0 to 4 bits): indicates the time domain resource allocation according to the previous description.

[0116] - VRB to PRB mapping (1 bit): 0 indicates non-interleaved VRP to PRB mapping, 1 indicates interleaved VRP to PRB mapping.

[0117] - Modulation and coding scheme (5 bits): Indicates the modulation order and coding rate used for PDSCH transmission.

[0118] - New data indicator (1 bit): indicates whether the PDSCH corresponds to initial transmission or retransmission according to toggling.

[0119] - Redundancy version (2 bits): indicates the redundancy version used for PDSCH transmission.

[0120] -HARQ process number (4 bits): indicates the number of HARQ processes used for PDSCH transmission.

[0121] - Downlink Allocation Index (DAI) (2 bits): DAI indicator.

[0122] - TPC command for scheduled PUCCH (2 bits): PUCCH power control indicator.

[0123] - PUCCH resource indicator (3 bits): PUCCH resource indicator, indicating one of eight resources configured via higher layers.

[0124] -PDSCH to HARQ feedback timing indicator (3 bits): HARQ feedback timing indicator, indicating one of eight feedback timing offsets configured via higher layers.

[0125] 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, DCI format 1_1 includes at least the following information.

[0126] - Identifier of DCI format (1 bit): DCI format indicator, which can be set to 1.

[0127] - Carrier indicator (0 or 3 bits): Indicates the CC (or cell) transmitting the PDSCH allocated by the DCI.

[0128] - Bandwidth part indicator (0, 1 or 2 bits): Indicates the BWP for transmitting the PDSCH allocated by the DCI.

[0129] - Frequency domain resource allocation (payload is determined according to the aforementioned frequency domain resource allocation): indicates frequency domain resource allocation. is the size of the active DL BWP. The detailed method is shown in the aforementioned frequency domain resource allocation.

[0130] - Time domain resource allocation (0 to 4 bits): indicates the time domain resource allocation according to the previous description.

[0131] - VRB to PRB mapping (0 or 1 bit): 0 indicates non-interleaved VRP to PRB mapping, 1 indicates interleaved VRP to PRB mapping. When the frequency domain resource allocation is set to resource type 0, this information is 0 bit.

[0132] -PRB bundling size indicator (0 or 1 bit): When the higher layer parameter prb-BundlingType is not set or is set to "static", this information is 0 bit; when the higher layer parameter prb-BundlingType is set to "dynamic", this information is 1 bit.

[0133] - Rate matching indicator (0, 1 or 2 bits): Indicates the rate matching mode.

[0134] -ZP CSI-RS trigger (0, 1 or 2 bits): indicator triggers aperiodic ZP CSI-RS.

[0135] For transport block 1:

[0136] - Modulation and coding scheme (5 bits): Indicates the modulation order and coding rate used for PDSCH transmission.

[0137] - New data indicator (1 bit): Indicates whether the PDSCH corresponds to an initial transmission or a retransmission according to the handover.

[0138] - Redundancy version (2 bits): indicates the redundancy version used for PDSCH transmission.

[0139] -For transport block 2:

[0140] - Modulation and coding scheme (5 bits): Indicates the modulation order and coding rate used for PDSCH transmission.

[0141] - New data indicator (1 bit): Indicates whether the PDSCH corresponds to an initial transmission or a retransmission according to the handover.

[0142] - Redundancy version (2 bits): indicates the redundancy version used for PDSCH transmission.

[0143] -HARQ process number (4 bits): indicates the number of HARQ processes used for PDSCH transmission.

[0144] - Downlink Allocation Index (0, 2 or 4 bits): DAI indicator.

[0145] - TPC command for scheduled PUCCH (2 bits): PUCCH power control indicator.

[0146] - PUCCH resource indicator (3 bits): PUCCH resource indicator, indicating one of eight resources configured via higher layers.

[0147] -PDSCH to HARQ feedback timing indicator (3 bits): HARQ feedback timing indicator, indicating one of eight feedback timing offsets configured via higher layers.

[0148] - Antenna port (4, 5 or 6 bits): indicates a DMRS port and a code division multiplexing (CDM) group without data.

[0149] -Transmission Configuration Indication (0 or 3 bits): TCI indicator.

[0150] - SRS request (2 or 3 bits): SRS transmission request indicator.

[0151] -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.

[0152] -CBG clear 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 can be combined in retransmission reception.

[0153] -DMRS sequence initialization (0 or 1 bit): DMRS scrambling ID selection indicator.

[0154] The maximum number of DCIs with different sizes that a UE can receive in each time slot in a cell is 4. The maximum number of DCIs with different sizes scrambled with a C-RNTI that a UE can receive in each time slot in a cell is 3.

[0155] Antenna port indication may be indicated by the following Tables 7 to 10.

[0156] Table 7 Antenna port (1000+DMRS port), dmrs-Type=1, maxLength (maximum length)=1

[0157]

[0158]

[0159] Table 8 Antenna port (1000+DMRS port), dmrs-Type=1, maxLength=2

[0160]

[0161]

[0162] Table 9 Antenna port (1000+DMRS port), dmrs-Type=2, maxLength=1

[0163]

[0164] Table 10 Antenna port (1000+DMRS port), dmrs-Type=2, maxLength=2

[0165]

[0166]

[0167]

[0168] Table 7 is a table used when the dmrs-type is indicated to be 1 and the maxLength is 1. Table 8 is a table used when dmrs-Type=1, maxLength=2. When dmrs-type=2, maxLength=1, Table 9 is used to indicate the DMRS port used, and when drms-type is 2 and maxLength is 2, Table 10 is used to indicate the DMRS port used. In Tables 7 to 10, the numbers 1, 2, and 3 indicated by the number of DMRS CDM groups with no data refer to CDM groups {0}, {0, 1}, and {0, 1, 2}, respectively. The DMRS ports are arranged in order according to the index of the port used. The antenna port is represented by the DMRS port + 1000. As shown in Tables 11 and 12, the CDM group of DMRS is connected to the method for generating DMRS sequence and antenna port.

[0169] The following Table 11 shows parameters when dmrs-type=1 is used, and the following Table 12 shows parameters when dmrs-type=2 is used.

[0170] Table 11 Parameters for PDSCH DMRS dmrs-type=1

[0171]

[0172] Table 12 Parameters of PDSCH DMRS dmrs-type=2

[0173]

[0174] The DMRS sequence according to the parameters is determined by Equation 1 as follows.

[0175] [Equation 1]

[0176]

[0177] When only one codeword is enabled in Table 7 and Table 8, rows 2, 9, 10, 11, and 30 are only used for single-user MIMO. That is, the UE may not assume that different UEs are co-scheduled and may not perform multi-user MIMO reception operations such as multi-user interference cancellation, nulling, or whitening.

[0178] When only one codeword is enabled in Tables 9 and 10, rows 2, 10, and 23 are only used for single-user MIMO. That is, the UE may not assume that different UEs are co-scheduled and may not perform multi-user MIMO reception operations such as multi-user interference cancellation, nulling, or whitening.

[0179] Fig. 9 A cooperative communication antenna port configuration according to an embodiment is shown.

[0180] Fig. 9 The radio resource allocation of each transmission reception point (TRP) according to the joint transmission (JT) technology and situation is shown. Fig. 9 In the figure, 900 shows coherent joint transmission (C-JT) supporting inter-precoding between single cells, TRPs and / or beams. In C-JT, TRP A 905 and TRP B 910 transmit the same data (PDSCH), and multiple TRPs perform joint precoding, which indicates that TRP A 905 and TRP B 910 transmit the same DMRS port (e.g., both TRPs 905 and 910 transmit DMRS ports A and B) for receiving the same PDSCH. In this case, UE 915 receives one DCI for receiving one PDSCH demodulated by DMRS ports A and B.

[0181] exist Fig. 9In the figure, 920 shows non-coherent joint transmission (NC-JT) supporting non-coherent precoding between a single cell, TRP and / or beam. In NC-JT, a single cell, TRP and / or beam transmits different PDSCHs, and a single precoding can be applied to each data (or PDSCH), which indicates that TRP A 925 and TRP B 930 transmit different DMRS ports (e.g., TRP A 925 transmits DMRS port A, and TRP B 930 transmits DMRS port B) for receiving different PDSCHs. In this case, UE 935 receives two types of DCI for receiving PDSCH A demodulated by DMRS port A and PDSCH B demodulated by DMRS port B.

[0182] In order to support NC-JT in which two or more transmission points provide data to one UE at the same time, it is necessary to allocate PDSCHs transmitted from two (or two or more) different transmission points through a single PDCCH, or to allocate PDSCHs transmitted from two or more different transmission points through multiple PDCCHs. Based on L1 / L2 / L3 signaling, the UE can obtain the QCL relationship between reference signals or channels, and can effectively estimate the large-scale parameters of the reference signals or channels through the QCL relationship. When the transmission points of a certain reference signal or channel are different, large-scale parameters are difficult to share, so the base station needs to simultaneously notify the UE of multiple quasi-co-location information about two or more transmission points through two or more TCI states when performing cooperative transmission. When non-coherent cooperative transmission is supported through multiple PDCCHs, that is, when two or more PDCCHs simultaneously allocate two or more PDSCHs to the same service cell and the same BWP, two or more TCI states can be allocated to corresponding PDSCHs and / or DMRS ports through corresponding PDCCHs. However, when non-coherent collaborative transmission is supported through a single PDCCH, that is, when one PDCCH simultaneously allocates two or more PDSCHs to the same serving cell and the same BWP, two or more TCI states need to be allocated to corresponding PDSCHs and / or DMRS ports through a single PDCCH.

[0183] Assuming that the DMRS ports allocated to the UE at a specific time are divided into a DMRS port group A transmitted from a transmission point A and a DMRS port group B transmitted from a transmission point B, two or more TCI states are connected to the corresponding DMRS port groups, and the channel can be estimated based on different QCL assumptions of the corresponding groups. Different DMRS ports can be subjected to code division multiplexing (CDM), frequency division multiplexing (FDM), or time domain multiplexing (TDM) to increase channel measurement accuracy and reduce transmission load. When the DMRS ports subjected to CDM are collectively referred to as CDM groups, since code-based multiplexing operates normally when the DMRS ports in the CDM group have similar channel characteristics (i.e., when the ports have similar channel characteristics, the ports are easily distinguished by orthogonal cover codes (OCC)), it may be important to ensure that the DMRS ports in the same CDM group do not have different TCI states. The present disclosure provides a method for indicating to a UE that there are no DMRS ports and CDM groups for data that meet the aforementioned characteristics.

[0184] In the following, for ease of description, Tables 7 to 12 are referred to as "first antenna port indication (or conventional antenna port indication)", and a table in which some or all code points in Tables 7 to 12 are modified is referred to as "second antenna port indication (new antenna port indication)". The allocation of DMRS ports and CDM groups without data is referred to as DMRS allocation.

[0185] The UE can determine the number of antenna ports used for PDSCH transmission by a table indicating the DMRS port. In DCI format 1_1, the antenna port indication method based on Rel-15 can be based on an index of 4 to 6 bits in length indicated by the antenna port field of the DCI, and thus the antenna port can be determined. Based on the indicator (index) transmitted by the base station, the UE can identify information about the number and index of DMRS ports of the PDSCH, the number of preamble symbols, and the number of CDM groups. In addition, based on the information in the transmission configuration indication (TCI) field in DCI 1_1, the UE can determine the dynamic change of the beamforming direction. When tci-PresentDCI is configured as "enabled" in a higher layer, the UE can identify the TCI field of three bits of information to determine the TCI state activated for the DL BWP or scheduled component carrier and the direction of the beam associated with the DL-RS. When tci-PresentDCI is disabled, the UE can assume that there is no change in the beam direction in the beamforming.

[0186] In various embodiments of the present disclosure, a scenario of allocating PDSCHs transmitted from two (or two or more) different transmission points via a single PDCCH is considered. Based on the TCI information and antenna port information in a single PDCCH, a Rel-15 UE can receive a single-layer or multi-layer PDSCH stream including quasi-co-located (QCLed). However, a Release 16 (Rel-16) UE can receive data transmitted in C-JT / NC-JT format from multiple TRPs or multiple base stations. In order to support C-JT / NC-JT, Rel-16 UEs require basic higher layer configuration. Specifically, for higher layer configuration, the UE needs a process for receiving and configuring parameters or setting values ​​related to C-JT / NC-JT.

[0187] [Example 1]

[0188] Base stations and UEs supporting C-JT / NC-JT disclose a separate DMRS port table for sending and receiving C-JT / NC-JT transmission signaling in a higher layer configuration. The disclosed DMRS port table is divided into a DMRS port table indicated by an antenna port field indicated based on DCI format 1_1 and a separate table. As a method for distinguishing between a DMRS port table and a DMRS port table in Rel-15, the base station and the UE can pre-configure information about whether NC-JT transmission is supported in the RRC configuration. That is, in RRC, whether NC-JT transmission is supported can be determined by a field, such as C-JT / NC-JT transmission = enable / disable.

[0189] A UE configured with C-JT / NC-JT transmission = enabled in a higher layer can indicate the field to be used by the UE by using the existing antenna port field in DCI format 1_1. Alternatively, according to an embodiment, the UE can use a separate field other than the antenna port field in DCI format 1_1 to indicate at least one of the number of detailed DMRS ports for NC-JT transmission, the number of DMRS CDM groups excluding data, the number of (maximum) preamble symbols, and the DMRS type.

[0190] The following Tables 12-1 to 12-4 disclose DMRS ports based on the CDM groups shown in Table 11, so that DMRS ports transmitted from the same TRP are transmitted to the same CDM group. In Tables 12-1 to 12-4, a semicolon (;) is used to indicate that the left and right DMRS ports are mapped to different TRP transmissions and different CDM groups, but depending on the embodiment, the semicolon can be omitted. The DMRS ports shown in the table show that the first TRP and the second TRP support a maximum of two DMRS ports. In addition, concepts such as basic DMRS ports, types, and the number of leading symbols shown in Tables 7 to 10 also apply.

[0191] As shown in Table 12-1, the DMRS port table of C-JT / NC-JT may support different types of ports that are not supported in Rel-15. For example, when the base station indicates entry 0 to the UE, the UE can determine that the DMRS port 0 and DMRS port 2 of the base station are transmitted from the first TRP and the second TRP, respectively. When the number of ports in each TRP is identified as 1, the UE can determine that a single-layer transmission is performed from the first TRP and the second TRP. When the base station indicates entry 1 to the UE, the UE can determine that the DMRS port 1 and DMRS port 3 of the base station are transmitted from the first TRP and the second TRP, respectively. When the number of ports in each TRP is identified as 1, the UE can determine that a single-layer transmission is performed from the first TRP and the second TRP. Although entry 1 has a different number of ports from entry 0, entry 1 is functionally similar to entry 0 and can therefore be omitted, and entry 1 is considered to overlap with entry 0.

[0192] When the base station indicates item 2 to the UE, the UE can determine that the base station transmits DMRS ports 0 and 1 from the first TRP and the second TRP. When it is identified that the number of ports in the corresponding TRP is two and one, the UE can determine that two-layer transmission is performed in the first TRP and one-layer transmission is performed in the second TRP. When the base station indicates item 3 to the UE, the UE can determine that the base station transmits DMRS port 0 from the first TRP, and transmits DMRS ports 2 and 3 from the remaining second TRP. When it is identified that the number of ports in the corresponding TRP is 1 and 2, the UE can determine that single-layer transmission is performed in the first TRP and double-layer transmission is performed in the second TRP. The operations of the base station and the UE for items 4 and 5 can be easily understood from the description of items 2 and 3. Although items 4 and 5 have different numbers of ports from items 2 and 3, items 4 and 5 are functionally similar and can therefore be omitted.

[0193] When the base station indicates entry 6 to the UE, the UE can determine that the base station transmits DMRS ports 0 and 1 from the first TRP, and transmits DMRS ports 2 and 3 from the second TRP. When the number of each port is identified as 2, the UE can determine to perform two-layer transmission in the first TRP, and perform two-layer transmission in the remaining second TRP. Table 12-1 shows embodiments of various situations in which the base station and the UE communicate in an entry format, and all or some of the seven entries can be applied to an actual system. Table 12-1 shows a case in which the base station transmits one codeword to the UE, and can be similarly applied to the case of transmitting two or more codewords.

[0194] Table 12-2 shows the case of DMRS type 1 which is the same as Table 12-1 and maxLength=2 which is different from Table 12-1. Referring to Tables 7 to 8, in the DMRS port configuration of C-JT / NC-JT, DMRS ports from 0 to 3 can be mapped in the same form as maxLength=1.

[0195] Table 12-3 is a DMRS port table for C-JT / NC-JT transmission of DMRS type 2, which is different from DMRS type 1 shown in Table 12-1. Table 12-3 supports up to 12 DMRS ports, which corresponds to a structure suitable for a multi-user MIMO (MU-MIMO) type. For example, when the base station indicates entry 0 to the UE, the UE can determine that the DMRS port 0 and DMRS port 2 of the base station are transmitted from the first TRP and the second TRP, respectively. When the number of ports in each TRP is identified as 1, the UE can determine that a single-layer transmission is performed from the first TRP and the second TRP. The entries in Table 12-3 show the case where the number of DMRS CDM groups is 2 and the number of DMRS CDM groups is 3 at the same time, but do not exclude the number of 2 and 3 represented in separate entries. The above embodiments are shown in an entry format, and some or all of the 14 entries can be applied to actual systems. For example, only some of the entries 0, 2, 3, 6, 7, 9, 10, and 13 can be used to determine the table. In addition, the order of the entries in the above embodiments is only an embodiment and does not limit the present disclosure. The table described above relates to when the base station transmits one codeword to the UE, and can be similarly applied when two or more codewords are transmitted.

[0196] Table 12-4 shows when the DMRS type is the same as 2 in Table 12-3 and the maxLength is different from 2 in Table 12-3. Referring back to Tables 7 to 8, in the DMRS port configuration of C-JT / NC-JT, a total of 2 to 4 DMRS ports are allocated, and at least one DMRS port is allocated to each CDM group. According to the number of preamble symbols, when the number of preamble symbols is 1, the DMRS ports are allocated within DMRS ports 0 to 3 (the same as Table 12-3, so omitted), and when the number of preamble symbols is 2, the DMRS ports are allocated within DMRS ports 0 to 7. When a total of two DMRS ports are used, each CDM group needs to use the same frequency domain orthogonal cover code (OCC). The time domain OCC of each CDM group can be the same or different. For example, in each CDM group {0, 1}, DMRS ports 0 and 2 using the same time domain OCC can be used at the same time, and DMRS ports 0 and 6 using different time domain OCCs can also be used at the same time. When three or more DMRS ports are used in total, the time domain OCC applied to each CDM group {0, 1} may be the same or different. The above embodiment is shown in an entry format, and some or all of the 28 entries can be applied to an actual system. For example, only some entries 0, 2, 3, 6, 7, 9, 10 and 13 or entries 0, 2, 3, 6, 7, 9, 10, 13, 14, 16, 17, 20, 23, 24 and 27 can be used to determine the table. In addition, the order of the entries described above is an example and does not limit the present disclosure. The table described above shows when the base station transmits a codeword to the UE, and can be similarly applied to when two or more codewords are transmitted.

[0197] Table 12-1 DMRS indication table of antenna port (1000+DMRS port), dmrs-Type=1, maxLength=1

[0198]

[0199] Table 12-2 DMRS indication table of antenna port (1000+DMRS port), dmrs-Type=1, maxLength=2

[0200]

[0201]

[0202] Table 12-3 DMRS indication table of antenna port (1000+DMRS port), dmrs-Type=2, maxLength=1

[0203]

[0204] Table 12-4 DMRS indication table of antenna port (1000+DMRS port), dmrs-Type=2, maxLength=2

[0205]

[0206]

[0207] Example 2

[0208] The following Table 13-1 shows a method of using the code points of the reserved bits in the existing Rel-15 as a method for the base station to indicate the DMRS port to the UE for C-JT / NC-JT transmission. As shown in Table 7, in the Rel-15 DMRS port table, fields 0 to 11 are occupied, and fields 12 to 15 are not occupied as reserved bits. In an embodiment of the present disclosure, as shown in Table 13-1, four code points 12 to 15 in the DMRS port table can be used to indicate the DMRS ports for collaborative transmission transmitted from two TRPs. When the same reserved bits are used, the base station and the UE do not need to allocate separate fields, thereby efficiently using DCI resources.

[0209] For example, when the base station indicates entry 12 to the UE, the UE may determine that DMRS port 0 and DMRS port 2 of the base station are transmitted from the first TRP and the second TRP, respectively. When the number of ports in each TRP is identified as 1, the UE may determine that single-layer transmission is performed from the first TRP and the second TRP. Optionally, when the base station indicates entry 13 to the UE, the UE may determine that DMRS ports 0 and 1 of the base station are transmitted from the first TRP, while DMRS port 2 is transmitted from the second TRP. When the number of ports in the corresponding TRP is identified as two and one, the UE may determine that two-layer transmission is performed in the first TRP, and one-layer transmission is performed in the second TRP. Optionally, when the base station indicates entry 14 to the UE, the UE may determine that DMRS port 0 of the base station is transmitted from the first TRP, while DMRS ports 2 and 3 are transmitted from the remaining second TRP. When the number of ports in the corresponding TRP is identified as one and two, the UE may determine that single-layer transmission is performed in the first TRP, and double-layer transmission is performed in the second TRP. Optionally, when the base station indicates entry 15 to the UE, the UE can determine that DMRS ports 0 and 1 of the base station are transmitted from the first TRP, and DMRS ports 2 and 3 are transmitted from the second TRP. When it is identified that the number of ports in the corresponding TRP is two, the UE can determine to perform two-layer transmission in the first TRP and to perform two-layer transmission in the second TRP.

[0210] A UE configured with C-JT / NC-JT transmission = enabled in a higher layer can identify the remaining code points of the existing antenna port field in DCI format 1_1, thereby dynamically determining whether C-JT / NC-JT is performed. That is, when the antenna port field in DCI format 1_1 is 12 to 15, the UE can identify the number of TRPs for PDSCH transmission scheduled by DCI, the number of layers to be transmitted, the number of DMRSDCM groups without data, the number of preamble symbols, etc. The above embodiments are shown in an entry format, and some or all of the four entries can be applied to actual systems. The order of the entries in the above embodiments is only an embodiment and does not limit the present disclosure.

[0211] For example, the following Tables 13-2, 13-3, and 13-4 are embodiments defined in Rel-15 of adding some DMRS ports generated separately in Tables 12-2, 12-3, and 12-4 to Tables 8, 9, and 10, wherein overlapping DMRS ports are omitted to reduce the bit size. This omission is only one embodiment, and these tables can be supplemented using some or all of the DMRS ports shown in Tables 12-1 to 12-4. In addition, the base station can schedule joint transmission for Rel-16 NC-JT terminals as shown in Tables 12-1 to 13-4, and can simultaneously schedule single-port transmission for Rel-15 UEs on the same DMRS port, thereby performing downlink MU-MIMO operations.

[0212] Optionally, when the DMRS port indexes in some entries of Tables 13-1 to 13-4 are the same, the overlapping indexes can be omitted. That is, in Table 13-1, the port indexes in entries 12, 13, and 15 for NC-JT transmission are the same as those in entries 11, 9, and 10, and therefore can be omitted. In Table 13-2, the port indexes in entries 31, 32, and 34 for NC-JT transmission are the same as those in entries 11, 9, and 10, and therefore can be omitted. In Table 13-3, the port indexes in entries 24, 25, 27, 29, and 31 for NC-JT transmission are the same as those in entries 23, 9, 10, 29, and 22, and therefore can be omitted. In Table 13-3, the port indexes in entries 24, 25, 27, 29, and 31 for NC-JT transmission are the same as those in entries 23, 9, 10, 29, and 22, and therefore can be omitted. In Table 13-4, the port indexes in entries 58, 59, 61, 63, and 65 for NC-JT transmission are the same as those in entries 23, 9, 10, 20, and 22, and thus can be omitted. When the index is omitted, the overlapping entries can be omitted based on one of the following assumptions: assuming that for NC-JT, at least different CDM groups are not transmitted in the same port; assuming that the UE can distinguish the DMRS port of NC-JT as a TCI field indicating whether NC-JT is performed; and assuming that the DMRS port can be distinguished based on the reception of the MAC CE message and the reception of the DCI.

[0213] Table 13-1 DMRS indication table of antenna port (1000+DMRS port), dmrs-Type=1, maxLength=1

[0214]

[0215]

[0216] Table 13-2 DMRS indication table of antenna port (1000+DMRS port), dmrs-Type=1, maxLength=2

[0217]

[0218]

[0219] Table 13-3 DMRS indication table of antenna port (1000+DMRS port), dmrs-Type=2, maxLength=1

[0220]

[0221]

[0222] Table 13-4 DMRS indication table of antenna port (1000+DMRS port), dmrs-Type=2, maxLength=2

[0223]

[0224]

[0225] The base station may allocate at least two PDSCHs to the UE in a single PDCCH for multi-TRP operation based on eMBB or URLLC. Within a single time slot on the time axis, the PDSCHs may be allocated so as not to overlap each other on the frequency axis. One PDSCH may be associated with one of the TCI states configured by the base station for the UE. In addition, a single / multiple identical DMRS ports may be associated with the allocated resources so as not to overlap. In addition, the indicated codeword (CW) and a redundant version (RV) may be applied to all resources of the PDSCH allocated by the base station. The UE may apply a common RB mapping (mapping for each layer on the codeword side) to all allocated resources. In addition, the indicated codeword (CW) and a redundant version (RV) may be applied to a single resource that does not overlap on the frequency axis in the PDSCH resources allocated by the base station. The RVs applied to the corresponding PDSCH resources may be the same or different. The application of the RV that may be transmitted by the UE to the base station may be used as the UE capability of the UE. In addition, the UE may send the soft combining capability of the received codeword to the base station via a UE capability message. First, for NC-JT transmission, each TRP and UE supports up to two layers of transmission, where in single-layer transmission, up to two code blocks can be transmitted for each CW, and in two-layer transmission, one code block can be transmitted for each CW. The same MCS or different MCSs can be applied to PDSCH resources that are allocated so as not to overlap each other on the frequency axis.

[0226] The base station can allocate at least two PDSCHs to the UE in a single PDCCH for multi-TRP operation based on eMBB or URLLC. Within a single time slot on the time axis, the PDSCH may include resources allocated so as not to overlap with each other. When the base station transmits one CW (one TB), one transmission configuration indication (TCI) and one RV may be applied. In addition, the same MCS may be applied to all PDSCHs transmitted via at least one DMRS port within a single time slot. The foregoing description within a single time slot may apply to PDSCH resources allocated by the base station to different time slots.

[0227] The UE may support data transmitted in the form of C-JT / NC-JT from multiple TRPs or multiple base stations. A UE supporting C-JT / NC-JT may receive parameters or setting values ​​related to C-JT / NC-JT in a higher layer configuration, and may set the RRC parameters of the UE based on the parameters or setting values. For higher layer configurations, the UE may use the UE capability parameter tci-StatePDSCH. When it is determined that a codeword (CW) is transmitted through data scheduling, the base station may indicate to the UE one to four layers to transmit a TB mapped to one CW. This case corresponds to the case of maxLength=1 shown in Tables 7, 8, 12, 12-1 to 12-4, and 13-1 to 13-4. When it is determined that two CWs are transmitted through data scheduling, the base station may indicate to the UE five to eight layers to transmit two TBs mapped to two CWs. This case corresponds to the case of maxLength=2 shown in Tables 7, 8, 12, 12-1 to 12-4, and 13-1 to 13-4.

[0228] Various embodiments of the present disclosure propose retransmission (secondary transmission) after the initial transmission (first transmission) when the base station transmits two CWs. The base station may indicate that two CWs are transmitted using a single downlink control channel (first PDCCH) in TRP A or TRP B to transmit data to a specific UE. The detailed scheduling information of DCI format 1_1 of the first PDCCH may include the number of HARQ processes, antenna ports, and CBG transmission information, which are generally applied to data that is independent of the number of TBs, and may include a modulation and coding scheme (MCS), a new data indicator (NDI), and a separate redundancy version (RV) for each TB.

[0229] Fig.10 A cooperative communication based on two codewords according to an embodiment is shown.

[0230] refer to Fig.10, for example, 1010 shows a case where the base station maps CW 0 1020 and CW 1 1025 to six layers to transmit data to a specific UE, and 1060 shows a case where the base station maps CW 0 1070 and CW 1 1075 to five layers to transmit data to the specific UE. However, when the base station determines the TB for transmitting data to the specific UE as in 1010 and determines to use a total of six layers to transmit data to the UE, the base station indicates that three layers are transmitted by TRP A 1030 and three layers are transmitted by TRP B 1035. The DMRS port mapping by the antenna port indicator in TRP A 1030 and TRP B 1035 may be configured in various forms, but this embodiment shows that when the DMRS port table is mapped by each port indicator and the mapped DMRS port table is generated differently considering the same CDM group. That is, DMRS port table indexes 0, 1, 4, and 5 may be generated as the same CDM group 1, and DMRS port table indexes 2, 3, 6, and 7 may be generated as another same CDM group 2. The DMRS ports of CDM group 1 may be mapped to TRP A 1030, and the DMRS ports of CDM group 2 may be mapped to TRP B 1035. In this embodiment, the order and mapping of DMRS indexes are for illustration only and are not limited to different methods.

[0231] Alternatively, when the base station determines a TB for transmitting data to a specific UE as in 1060 and determines to transmit data to the UE using a total of five layers, the base station may instruct that two layers are transmitted by TRP A 1080 and three layers are transmitted in TRP B 1085. Considering the same code domain group (CDM), DMRS port mapping in TRP A 1080 and TRP B 1085 enables TRP A 1080 to perform transmission using DMRS ports 0 and 1, and enables TRP B 1085 to perform transmission using DMRS ports 2, 3, and 6. That is, with respect to the layers added after the five layers, the layers for CW 1 1075 may be added first, and then the layers for CW 0 1070 may be added. Although Fig.10 The case where the base station transmits two CWs is shown with five-layer transmission and six-layer transmission, but additional cases including seven-layer transmission and eight-layer transmission are not excluded, but can be easily inferred by extending the above description of five-layer transmission and six-layer transmission.

[0232] The UE may transmit ACK / NACK information indicating whether CW 0 (mapped to TB 1) 1020 and 1070 and CW 1 (mapped to TB 2) 1025 and 1075 transmitted from TRP A 1030 and 1080 and TRP B 1035 and 1085 are successfully received to the base station through the PUCCH or PUSCH resources allocated by the base station. In response to TB 1 and TB 2, each ACK / NACK information may be transmitted in units of TBs or in units of multiple CBGs, which are sets of CBs, depending on whether a code block group (CBG) is configured. When the base station configures a CBG retransmission operation, the UE may specify and indicate the CBG to be retransmitted to the base station in a retransmission using the CBG transmission information of DCI format 1_1. Specifically, when the CBG transmission information is zero, it may be assumed that the CBG was originally transmitted or retransmitted in the form of a TB. When the CBG transmission information is N (N=2, 4, 6, 8) bits, the CBG transmission information can sequentially indicate the CBG to be retransmitted among the N CBGs as 1, indicate the CBG not to be retransmitted as 0, and can indicate that the corresponding CBG is retransmitted.

[0233] In various embodiments of the present disclosure, Fig.10 As shown, the base station may map two code words (CW) 1020, 1025, 1070, and 1075 to TRP A 1030 and 1080 and TRP B 1035 and 1085 of the UE, and may transmit data including TB 1 and TB 2 mapped to CW 0 1020 and 1070 and CW 1 1025 and 1075. Depending on the result of receiving the data, the UE may successfully receive both TB 1 and TB 2, or may fail to receive at least one of TB 1 and TB 2.

[0234] Fig.11 A cooperative communication based on two codewords according to another embodiment is shown.

[0235] exist Fig.11In the figures, various methods are shown, in which, as described above, when the UE fails to receive a TB, the base station retransmits a TB (e.g., CW 0, TB 1). 1110 shows a method in which the UE transmits the result of successfully receiving TB 2 and failing to receive TB 1 to the base station, and the base station transmits CW 0 1120 to the UE based on the result using both TRP A 1130 and TRP B 1135TB 1 for retransmission. When CW 0 1120 is repeatedly transmitted from TRP A 1130 and TRP B 1135, the UE can guarantee the highest reception performance in consideration of the channel state or the spatial channel state according to beamforming. In particular, when additional coding gain is obtained in TRP A 1130 and TRPB 1135, the UE can maximize the probability of successful reception. It is assumed that TRP A 1130 transmits a single downlink control channel in both initial transmission and retransmission. However, the present disclosure is not limited thereto, and TRP B 1135 may transmit a single downlink control channel in both initial transmission and retransmission, or TRP A 1130 may transmit a single downlink control channel in initial transmission, and TRP B 1135 that has been successfully received may transmit a single downlink control channel in retransmission. Alternatively, TRP A 1130 and TRP B 1135 may transmit corresponding downlink control channels in both initial transmission and retransmission, or may transmit multiple downlink control channels in initial transmission, and TRP B 1135 that has been successfully received may transmit a single downlink control channel in retransmission.

[0236] 1110 shows a method of indicating repeated transmission of the same CW 0 1120 from TRP A 1130 and TRP B 1135 to the UE in retransmissions after an initial transmission. The base station may configure some control information of DCI format 1_1 in the first PDCCH as follows.

[0237] Example 1-1

[0238] Basically, when CBG transmission information (CBGTI) is configured in the DCI transmitted by the base station without changing the number of HARQ processes in retransmission after initial transmission, the CBG corresponding to TB 1 is transmitted, so only a part of the retransmitted CBG is transmitted as 1. For example, when TB 1 includes two CBGs and TB 2 includes two CBGs, the CBGTI field includes four bits. Specifically, when both CBGs of TB 1 are retransmitted, the CBGTI code point may be indicated as 1100, and when the first CBG of the CBG of TB 1 is retransmitted, the CBGTI code point may be indicated as 1000.

[0239] In addition, the base station may provide the UE with the layer for retransmission and the corresponding DMRS antenna port information in the antenna port field of the DCI. For example, the base station may indicate to the UE a code point including DMRS port indexes 0, 1, and 4 and DMRS port indexes 2, 3, and 6 in the antenna port field (4 to 6 bits). According to the configuration of the DMRS port table, the antenna port field may be configured in an associated manner to include various sets or pairs of 0, 1, 2, 3, 4, and 6. Optionally, the base station may indicate only DMRS port indexes 0, 1, and 4 or DMRS port indexes 2, 3, and 6 in the antenna port field (4 to 6 bits). That is, when three layer related information (e.g., including DMRS port indexes 0, 1, and 4) is indicated according to the configuration of the DMRS port table, the transmission of all DMRS port indexes 0, 1, 2, 3, 4, and 6 is implicitly indicated, and the UE may implicitly determine the antenna port of the transmission.

[0240] In addition, in the MCS of TB 1 of the DCI, since the initial transmission fails, the base station may indicate to the UE the same code point as the MCS of TB 1 used for the initial transmission according to the scheduling of the base station in the retransmission, or may change the code point of the MCS according to the resource allocation and the channel change. However, the base station may indicate the reserved code (#29 to #31) for the MCS of TB 2 of the DCI. When the base station transmits the reserved code, the UE may receive the reserved code information in the MCS for TB 2, and may implicitly determine to retransmit TB 1 in the DMRS port for TB 2 based on the value. For example, when the MCS of TB 2 is a value of the reserved code point (e.g., #29), it may be determined that the MCS transmitted from TRP B 1135 is the same as the MCS of TB 1 retransmitted from TRP A 1130. In other examples, when the MCS of TB2 is a value of a reserved code point (e.g., #30), it can be determined that the MCS from TRP B 1135 is the same as the MCS of TB 2 originally transmitted from TRP B 1135.

[0241] In response to the UE failing to receive TB 1, the base station may indicate the same NDI code point value for TB 1 without handing over the NDI code point value. Since the UE has successfully received TB 2 in the initial transmission, when TRP B 1135 repeatedly transmits TB 1, the NDI code point value of TB 2 may be indicated as the handover value.

[0242] In addition, considering the soft combining gain of TB 1 retransmitted from TRP A 1130 on the UE side and TB 1 transmitted from TRP B 1135, the base station may transmit the RV code point of TB 1 of the DCI as 0, and the RV code point of TB 2 as 0 or 3. In contrast, the base station may transmit the RV code point of TB 1 as 3, and the RV code point of TB 2 as 0. In the initial transmission, when a part of the CBG is successfully received (CBG clear information = 1), the base station may transmit the RV code point of TB 1 as 2, and the RV code point of TB 2 as 3.

[0243] That is, based at least on the DMRS port explicitly indicated in the antenna port field and the reserved code point information of the MCS field of TB2, the UE can determine the repeated transmission of instance 11-10.

[0244] Example 1-2

[0245] An additional method is proposed for performing repeated transmission from TRP A 1130 and TRP B 1135 by assuming that the number of HARQ processes, antenna port field and RV in DCI format 1_1 of PDCCH are the same as those in the above-mentioned embodiment 1110, and by changing the MCS, NDI and CBGTI code point values.

[0246] When the initial transmission fails, as in 1110, the base station can flexibly indicate the MCS (0 to 28) of TB 1 transmitted to the UE from TRP A 1130 and the MCS (0 to 28) of TB 2 transmitted to the UE from TRP B 1135, taking into account the TB size and the channel state. When the dynamically changeable MCS field is indicated, the UE cannot identify whether the data of TB 2 transmitted from TRP B 1135 is mapped to CW 0 or CW 1 using only the indicated DMRS port index.

[0247] In order to distinguish data, the NDI field present in each TB in the DCI is used. NDI is used to determine whether new data is transmitted in units of TB. When the received NDI value is transferred from 0 to 1 and from 1 to 0, the UE determines that new data is received, and when the received NDI value is not transferred from 0 to 0 and from 1 to 1, the UE determines that the previous data is retransmitted. For example, the base station can indicate the same NDI code point value for TB 1 without transferring the NDI code point value in response to the UE's failure to receive TB 1. Since the UE has successfully received TB 2 in the initial transmission, when TRP B 1135 repeatedly transmits TB 1, the base station can indicate the NDI code point value of TB 2 as the value of the transfer. In other examples, when the base station identifies the HARQ ACK / NACK information received from the UE and identifies that the transmission of at least one of TB 1 and TB 2 has failed, the base station may not transfer NDI 1 and NDI 2, but may indicate the same value as the value transmitted in the initial transmission. Finally, considering the result of the initial transmission from the base station (HARQ ACK / NACK information transmitted to the base station), the UE can determine that TB 1, which the UE did not receive, was repeatedly transmitted from TRP A 1130 and TRP B 1135.

[0248] In other examples, when the base station configures CBG retransmission in addition to the NDI information and two CBGs are configured for each TB, the base station may indicate the CBGTI field as 1100, 1000, and 0100 to indicate that TB1 is retransmitted to the UE. Based on the unhanded NDI 1 and NDI 2 and the CBGTI information (e.g., 1100), the UE may determine that TB 1 is retransmitted and TB 2 is not retransmitted.

[0249] In addition, when the base station determines that soft combining of TB 1 originally transmitted from TRP A1130 and retransmitted TB 1 is impossible or unnecessary based on the HARQ ACK / NACK message transmitted by the UE, the base station may perform retransmission by fixing all NDIs or by indicating CBG clear information (CGBFI) as a value of 0. In addition, when the base station cannot identify a NACK response transmitted by the UE or an ACK response of the UE, if transmission of TB 1 or TB 2 fails, the base station may indicate the same value of the NDI code points of TB 1 and TB 2 without handing over the NDI code points.

[0250] That is, the UE may determine the repeated transmission of instance 11-10 based at least on the result of the initial transmission and whether the value of the NDI field is handed over or the indicated CBGTI value.

[0251] 1140 shows a method of retransmitting transmission CW 0 1150 of TB 1 using one TRP (e.g., TRP B 1165) when the UE successfully receives TB 2 (CW1 1155) and fails to receive TB 1 (CW 0 1150). In this embodiment, the base station maps CW 0 1150 to TRP B 1165 and repeatedly transmits CW 0 1150 to avoid the channel where the initial transmission failed, and uses the channel where the initial transmission succeeded when transmitting CW 0 1150. In this embodiment, it is assumed that a single downlink control channel is transmitted from TRP A 1160 or TRP B 1165 in both the initial transmission and the retransmission. However, the present disclosure is not limited to this illustration. 1140 shows a method in which a base station indicates data to be transmitted in a retransmission following an initial transmission by changing from TRP A 1160 (DMRS antenna ports: 0, 1, and 4) to TRP B 1165 (DMRS antenna ports 2, 3, and 6), wherein the base station may configure some control information of DCI format 1_1 in the first PDCCH as follows.

[0252] Example 2

[0253] Basically, when CBG transmission information (CBGTI) is configured in the DCI transmitted by the base station without changing the number of HARQ processes in retransmission after initial transmission, the CBG corresponding to TB 1 is transmitted, so only a part of the retransmitted CBG is transmitted as 1. For example, when TB 1 includes two CBGs and TB 2 includes two CBGs, the CBGTI field includes four bits. Specifically, when both CBGs of TB 1 are retransmitted, the CBGTI code point may be indicated as 1100, and when the second CBG of the CBG of TB 1 is retransmitted, the CBGTI code point may be indicated as 0100.

[0254] In addition, for example, the base station may indicate to the UE a code point including DMRS port indexes 2, 3, and 6 in the antenna port field (4 to 6 bits). According to the configuration of the DMRS port table, the antenna port field may be configured in an associated manner to include various sets or pairs of 2, 3, and 6. In other examples, the base station may repeatedly indicate the same antenna port field used for initial transmission in retransmissions. That is, a code point including DMRS port indexes 0, 1, and 4 and DMRS port indexes 2, 3, and 6 may be indicated. According to the configuration of the DMRS port table, the antenna port field may be configured in an associated manner to include various sets or pairs of 0, 1, 2, 3, 4, and 6. When the base station indicates the same antenna port as in the initial transmission, the UE may determine the effective DMRS port for actual transmission only after additionally identifying the MCS, NDI, and RV fields of TB 1 or TB 2.

[0255] In addition, considering the resource allocation of the base station and the channel between the base station and the UE, the MCS of TB 1 of the DCI indicates the code point of the appropriate MCS, and the base station can zero-fill, for example, the MCS field (five bits), the RV field (two bits), and the NDI (one bit) field of TB 2. In other examples, the base station can indicate a code point (e.g., #31) among the MCS reserved bits (#29 to #31) of TB 2, thereby indicating that TB 2 mapped to CW 1 1155 is not transmitted from TRP A 1160. In other examples, the base station can indicate the MCS code point of TB 2 as #26 (optionally, #25 to #28) and the RV as 1 (optionally, 3), thereby indicating to the UE that the configuration of TB 2 is disabled, and therefore the transmission of TB 2 is not performed. Specifically, when the higher layer parameter maxNrofCodeWordsScheduled-ByDCI is configured to 2 (the case where two CWs are enabled), the base station can disable the configuration by indicating the MCS of TB2 as 26 and the RV as 1, so that the UE receiving the MCS and RV information can determine that only TB1 is transmitted.

[0256] In addition, since the same data as in the initial transmission is transmitted, the NDI code point value of TB 1 in the DCI can indicate the same value as in the initial transmission. However, since the NDI code point value of TB 2 does not significantly affect the UE's determination, the base station can indicate the NDI code point value with or without handover.

[0257] In addition, considering the soft combining gain of TB 1 retransmitted from TRP A 1160 in the initial transmission and TB 1 transmitted from TRP B 1165 in the retransmission, the base station can transmit the RV code point of TB 2 as 0 or 3.

[0258] That is, in this embodiment, the UE may determine the repeated transmission of 1140 based at least on the DMRS port explicitly indicated in the antenna port field and the code point of the MCS field of the TB 2 that is not transmitted.

[0259] Although this embodiment shows the base station indicating data transmission of CW 0 1150 to TRP B 1165, i.e., DMRS port indices 2, 3, and 6, based on the details presented above, for ease of implementation rather than performance purposes, it can be fully inferred that the indication is to TRP A 1160, i.e., DMRS port indices 0, 1, and 4.

[0260] 1170 shows a method of retransmitting transmission CW 0 of TB 1 using two TRPs of TRP A 1190 and TRP B 1195 when the UE successfully receives TB 2 but fails to receive TB 1. The present embodiment discloses a method of performing retransmission within a restriction range using all two TRPs (TRP A 1190 and TRP B 1195) for retransmitting CW 0, the restriction range being that, as in Embodiment 1, a maximum of four layers can be transmitted to transmit CW 0, and following a sequential sequence of mapping by the antenna port and layer of the base station. In this embodiment, it is assumed that a single downlink control channel is transmitted from TRP A 1190 or TRP B 1195 in both initial transmission and retransmission. However, the present disclosure is not limited to this illustration. 1170 shows a method in which the base station indicates the retransmission to the UE using NC-JT based on TRP A 1190 or TRP B 1195 in the retransmission after the initial transmission, wherein the base station can configure some DCI format 1_1 control information in the first PDCCH as follows.

[0261] Example 3

[0262] Basically, when the base station configures the CBG transmission information (CBGTI) in the DCI transmitted by the base station in the retransmission after the initial transmission without changing the number of HARQ processes, the CBG corresponding to TB 1 is transmitted, so only a part of the retransmitted CBG is transmitted as 1. For example, when TB 1 includes two CBGs and TB 2 includes two CBGs, the CBGTI field includes four bits. Specifically, when all two CBGs of TB 1 are retransmitted, the CBGTI code point may be indicated as 1100, and when the first CBG of the CBG of TB 1 is retransmitted, the CBGTI code point may be indicated as 1000.

[0263] In addition, for example, the base station may indicate to the UE that the code points of DMRS port indexes 0, 1, and 3 are included in the antenna port field (4 to 6 bits) of the DCI. According to the configuration of the DMRS port table, the antenna port field may be configured in an associated manner to include various sets or pairs of DMRS port indexes 0, 1, and 3. Specifically, this embodiment follows the mapping order of Rel-15 and indicates that the DMRS port table sequence based on the initial transmission includes the highest three port indexes of the port index. In other examples, in 1170, only one layer in CW 0 1180 may be mapped to DMRS port index 0 through TRP A 1190, and two layers in CW 0 1180 may be mapped to DMRS port indexes 2 and 3 through TRP B 1195. When the port mapping (DMRS port indexes 0, 2, and 3) shown in this embodiment may include indexes 0, 2, and 3 in two CW DMRS tables based on NC-JT agreed between the base station and the UE, or the included sets (or pairs) are configured in an associated manner, the base station may perform a flexible layer mapping operation for the UE.

[0264] In addition, considering the resource allocation of the base station and the channel between the base station and the UE, the MCS of TB 1 indicates the code point of the appropriate MCS, and the base station can zero-fill, for example, the MCS field (five bits), the RV field (two bits), and the NDI field (one bit) of TB 2. In other examples, the base station can indicate a code point (e.g., #31) among the MCS reserved bits (#29 to #31) of TB 2, thereby indicating that TB 2 mapped to CW 1 1185 is not transmitted from TRP A 1190. In other examples, the base station can indicate the MCS code point of TB 2 as #26 (optionally, #25 to #28) and the RV as 1 (optionally, 3), thereby indicating to the UE that the configuration of TB 2 is disabled, and therefore the transmission of TB 2 is not performed. Specifically, when the higher layer parameter maxNrofCodeWordsScheduledByDCI is configured to 2 (the case where two CWs are enabled), the base station can disable the configuration by indicating the MCS of TB2 as 26 and the RV as 1, so that the UE receiving the MCS and RV information can determine that only TB1 is transmitted.

[0265] In addition, since the same data as in the initial transmission is retransmitted, the NDI code point value of TB 1 can indicate the same value as in the initial transmission. However, since the NDI code point value of TB 2 does not significantly affect the UE's determination, the base station can indicate the NDI code point value with or without handover.

[0266] In addition, considering the soft combining gain of TB 1 retransmitted from TRP A 11-90 in the initial transmission and TB 1 transmitted from TRP B 1195 in the retransmission, the base station can transmit the RV code point of TB 2 as 0 or 3.

[0267] That is, in this embodiment, the UE may determine the repetition transmission of x+1_3 based at least on the DMRS port explicitly indicated in the antenna port field and the code point of the MCS field of the untransmitted TB 2.

[0268] Although all the above embodiments consider the case where the base station retransmits TB 1, it can be fully inferred from the above embodiments that the UE retransmits TB 2 when it successfully receives TB 1 and fails to receive TB 2 in the initial transmission (or vice versa).

[0269] Fig.12 A cooperative communication based on two codewords according to another embodiment is shown.

[0270] Fig.12 Shows the combination Fig.11 The operations of the UE shown in the described embodiments 1 to 3. In step 1200, the UE may receive configuration for NC-JT and RRC related information for transmitting two CWs by the base station.

[0271] In step 1210, the UE may receive at least one PDCCH transmitted from TRP A or TRP B, and in step 1220, the UE may identify relevant control information.

[0272] The control information is information indicated in DCI format 1_1 of PDCCH, and may include at least an antenna port indicator, a HARQ process number and CBGTI information of NC-JT commonly applied to TB1 and TB 2, and MCS, RV and NDI applied to each TB.

[0273] In step 1230, the UE may determine whether to transmit one TB (TB 1 or TB 2) or multiple TBs (TB 1 and TB 2) based on the control information. In step 1240, based on some of the control information, the UE determines whether the transmission is an initial transmission (first transmission) or a retransmission (second transmission), may store data transmitted from one or more TRPs (TRP A and / or TRP B), and may perform a decoding operation or a soft combining operation. Specifically, in the soft combining operation, when two CWs are first transmissions, the UE may obtain a decoding gain between TRP A and TRP B in the same order transmission (if possible). In retransmission, the UE may determine whether to obtain a decoding gain between the first transmission and the second transmission, whether to obtain a decoding gain between TRPA and TRP B in the same order transmission, or whether to obtain the above two decoding gains for the two CWs.

[0274] The various embodiments described above show that, considering a single PDCCH-based NC-JT, the UE receives one PDCCH for NC-JT from TRP A or TRP B based on the PDCCH, and receives TB 1 and TB 2 from multiple TRPs. However, the UE can receive one PDCCH for NC-JT from each of TRP A and TRPB (receiving multiple PDCCHs), and can receive data from multiple TRPs based on the PDCCH. In this case, depending on the resource conditions of the first PDSCH and the second PDSCH to which the data is allocated, the UE may be able to receive multiple TBs, or may be restricted from receiving multiple TBs.

[0275] For example, when a first PDSCH transmitted from TRP A and a second PDSCH transmitted from TRP B are allocated to at least some overlapping symbols (eg, symbol 1 and symbol 2) in the same slot, the UE may operate as follows.

[0276] The UE may not expect to receive TB 1 and TB 2 transmitted on the first PDSCH and TB 1' and TB 2' transmitted on the second PDSCH from the base station. Alternatively, according to the UE capability of the UE, the UE may receive TB 1 and TB 2 transmitted on the first PDSCH and TB 1' and TB 2' transmitted on the second PDSCH. Alternatively, according to the UE capability of the UE, the UE may selectively receive the first PDSCH or the second PDSCH among TB 1 and TB 2 transmitted on the first PDSCH and TB 1' and TB 2' transmitted on the second PDSCH.

[0277] In other examples, when the first PDSCH transmitted from TRP A and the second PDSCH transmitted from TRP B are assigned to at least some symbols (e.g., symbol 1 and symbol 2) that are time-spaced in the same time slot, the UE may operate as follows. The UE may not expect to receive TB 1 and TB 2 transmitted on the first PDSCH and TB 1' and TB 2' transmitted on the second PDSCH from the base station. Alternatively, depending on the UE capabilities of the UE, the UE may receive TB 1 and TB 2 transmitted on the first PDSCH and TB 1' and TB 2' transmitted on the second PDSCH. Alternatively, depending on the UE capabilities of the UE, the UE may selectively receive the first PDSCH or the second PDSCH among TB 1 and TB 2 transmitted on the first PDSCH and TB 1' and TB 2' transmitted on the second PDSCH.

[0278] In other examples, when the first PDSCH transmitted from TRP A and the second PDSCH transmitted from TRP B are allocated to different time slots, the UE may operate as follows. The UE may not expect to receive TB 1 and TB 2 transmitted on the first PDSCH and TB 1' and TB 2' transmitted on the second PDSCH from the base station. Alternatively, the UE may receive TB 1 and TB 2 transmitted on the first PDSCH and TB 1' and TB 2' transmitted on the second PDSCH according to the UE capability of the UE.

[0279] Fig.13 A structure of a UE in a wireless communication system according to an embodiment is shown.

[0280] refer to Fig.13 , the UE may include a UE receiver 1300 , a UE transmitter 1310 and a UE processor 1305 .

[0281] The UE receiver 1300 and the UE transmitter 1310 may be collectively referred to as a transceiver. The UE receiver 1300, the UE transmitter 1310, and the UE processor 1305 of the UE may operate according to the aforementioned communication method of the UE. However, the components of the UE are not limited to the aforementioned examples. For example, the UE may include additional components (e.g., memory) or fewer components than the aforementioned components. In addition, the UE receiver 1300, the UE transmitter 1310, and the UE processor 1305 may be configured as a single chip.

[0282] The UE receiver 1300 and the UE transmitter 1310 (or transceiver) can send signals to and receive signals from the base station. The signals may include control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying the transmitted signal frequency and an RF receiver for low-noise amplification of the received signal and down-converting the received signal frequency. However, this is only one embodiment of the transceiver, and the components of the transceiver are not limited to the RF transmitter and the RF receiver.

[0283] In addition, the transceiver may receive a signal through a radio channel to output the signal to the UE processor 1305 , and may transmit a signal output from the UE processor 1305 through the radio channel.

[0284] The memory (not shown) may store programs and data required for the operation of the UE. In addition, the memory may store control information or data included in the signal obtained by the UE. The memory may be configured as a storage medium such as a ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media.

[0285] The UE processor 1305 may control a series of processes so that the UE may operate according to the aforementioned embodiments. The UE processor 1305 may be configured as a controller or one or more processors.

[0286] Fig.14 is a block diagram showing a structure of a base station in a wireless communication system according to an embodiment.

[0287] refer to Fig.14 , the base station may include a base station receiver 1400, a base station transmitter 1410 and a base station processor 1405.

[0288] The base station receiver 1400 and the base station transmitter 1410 may be collectively referred to as a transceiver. The base station receiver 1400, the base station transmitter 1410, and the base station processor 1405 of the base station may operate according to the aforementioned communication method of the base station. However, the components of the base station are not limited to the above examples. For example, the base station may include additional components (e.g., memory) or fewer components than the aforementioned components. In addition, the base station receiver 1400, the base station transmitter 1410, and the base station processor 1405 may be configured as a single chip.

[0289] The base station receiver 1400 and the base station transmitter 1410 (or transceiver) can send signals to and receive signals from the UE. The signals may include control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying the transmitted signal frequency and an RF receiver for low-noise amplification and down-converting the received signal frequency. However, this is only one embodiment of the transceiver, and the components of the transceiver are not limited to the RF transmitter and the RF receiver.

[0290] In addition, the transceiver may receive a signal through a radio channel to output the signal to the base station processor 1405, and may transmit a signal output from the base station processor 1405 through the radio channel.

[0291] The memory (not shown) may store programs and data required for the base station operation. The memory may store control information or data included in the signal obtained by the base station. The memory may be configured as a storage medium such as a ROM, RAM, hard disk, CD-ROM, and DVD, or a combination of storage media.

[0292] The base station processor 1405 may control a series of processes so that the base station can operate according to the aforementioned embodiments. The base station processor 1405 may be configured as a controller or one or more processors.

[0293] The embodiments of the present disclosure described and shown in the specification and the drawings are only specific examples, which are presented to easily explain the technical content of the present disclosure and help understand the present disclosure, and are not intended to limit the scope. That is, it is obvious to those skilled in the art that other variations based on the technical concept of the present disclosure can be implemented. As needed, the above-mentioned various embodiments can be applied in combination. For example, embodiments 1 to 3 of the present disclosure can be partially combined to operate a base station and a terminal.

Claims

1. A method performed by a terminal in a wireless communication system, the method comprising: receiving, from a base station, control information for scheduling downlink transmission using at least one transmit-receive point TRP; identifying, based on the control information, that at least a portion of a signal transmitted by a first TRP of at least one TRP is to be retransmitted by a second TRP of the at least one TRP; identifying, based on the control information, at least one demodulation reference signal (DMRS) port associated with a code division multiplexing (CDM) group of the second TRP for receiving the at least a portion of the signal; receiving the at least a portion of the signal from the second TRP based on at least one DMRS port associated with a CDM group of the second TRP; as well as Combine the signal received from the first TRP and at least a portion of the signal received from the second TRP.

2. The method according to claim 1, wherein: The control information includes information about the CDM group of the second TRP, DMRS port information indicating at least one DMRS port associated with the CDM group of the second TRP, modulation and coding scheme MCS information, new data indicator NDI, code block group transmission information CBGTI and at least one of code block group clearing information CBGFI.

3. The method according to claim 1, in, At least a portion of the signal received from the second TRP is demodulated based on the at least one DMRS port.

4. The method according to claim 1, wherein: Receive the entirety of the signal from the second TRP.

5. The method according to claim 1, wherein: The at least a portion of the signal is mapped to the same codeword.

6. A method performed by a base station in a wireless communication system, the method comprising: Generate control information for scheduling downlink transmission using at least one transmission reception point TRP, wherein the control information indicates that at least a portion of a signal transmitted by a first TRP of the at least one TRP is retransmitted by a second TRP of the at least one TRP, and indicates at least one demodulation reference signal (DMRS) port associated with a code division multiplexing (CDM) group of the second TRP for transmitting the at least a portion of the signal; sending the control information to the terminal; and The at least a portion of the signal is sent to the terminal using the second TRP based on at least one DMRS port associated with the CDM group of the second TRP.

7. The method according to claim 6, wherein: The control information includes information about the CDM group of the second TRP, DMRS port information indicating at least one DMRS port associated with the CDM group of the second TRP, modulation and coding scheme MCS information, new data indicator NDI, code block group transmission information CBGTI and at least one of code block group clearing information CBGFI.

8. The method according to claim 6, in, At least a portion of the signal sent from the second TRP is demodulated based on the at least one DMRS port.

9. The method according to claim 6, wherein: All of the signals are sent to the terminal using the second TRP.

10. The method according to claim 6, wherein: The at least a portion of the signal is mapped to the same codeword.

11. A terminal in a wireless communication system, the terminal comprising: Transceiver; and The controller is configured as: receiving, via the transceiver, from a base station control information for scheduling downlink transmission using at least one transmission reception point TRP; identifying, based on the control information, that at least a portion of a signal transmitted by a first TRP of at least one TRP is to be retransmitted by a second TRP of the at least one TRP; Based on the control information, identifying at least one demodulation reference signal (DMRS) port associated with a code division multiplexing (CDM) group of the second TRP for receiving the at least a portion of the signal; receiving, via a transceiver, the at least a portion of the signal from the second TRP based on at least one DMRS port associated with a CDM group of the second TRP; as well as Combine the signal received from the first TRP and at least a portion of the signal received from the second TRP.

12. The terminal according to claim 11, wherein: The control information includes information about the CDM group of the second TRP, DMRS port information indicating at least one DMRS port associated with the CDM group of the second TRP, modulation and coding scheme MCS information, new data indicator NDI, code block group transmission information CBGTI and at least one of code block group clearing information CBGFI.

13. The terminal according to claim 11, wherein: The controller is also configured to demodulate at least a portion of the signal received from the second TRP based on the at least one DMRS port.

14. The terminal according to claim 11, wherein: Receive the entirety of the signal from the second TRP.

15. The terminal according to claim 11, wherein: The at least a portion of the signal is mapped to the same codeword.

16. A base station in a wireless communication system, the base station comprising: Transceiver; and The controller is configured as: Generate control information for scheduling downlink transmission using at least one transmission reception point TRP, wherein the control information indicates that at least a portion of a signal transmitted by a first TRP of the at least one TRP is retransmitted by a second TRP of the at least one TRP, and indicates at least one demodulation reference signal (DMRS) port associated with a code division multiplexing (CDM) group of the second TRP for transmitting the at least a portion of the signal, sending the control information to the terminal via the transceiver, and Based on at least one DMRS port associated with the CDM group of the second TRP, at least a portion of the signal is sent to the terminal via a transceiver using the second TRP.

17. The base station according to claim 16, wherein: The control information includes information about the CDM group of the second TRP, DMRS port information indicating at least one DMRS port associated with the CDM group of the second TRP, modulation and coding scheme MCS information, new data indicator NDI, code block group transmission information CBGTI and at least one of code block group clearing information CBGFI.

18. The base station according to claim 16, wherein: At least a portion of the signal received from the second TRP is demodulated based on the at least one DMRS port.

19. The base station according to claim 16, wherein: The entirety of the signal is sent to the terminal using the second TRP.

20. The base station according to claim 16, wherein: The at least a portion of the signal is mapped to the same codeword.

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