CN116803174A - Method and apparatus for configuring repeated transmission and reception of downlink control information in wireless communication system - Google Patents
Method and apparatus for configuring repeated transmission and reception of downlink control information in wireless communication system Download PDFInfo
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Abstract
The present disclosure relates to a communication method and system for fusing internet of things (IoT) technology with a 5 th generation (5G) communication system supporting higher data rates than a 4 th generation (4G) system. The present disclosure may be applied to smart services based on 5G communication technology and IoT-related technology, such as smart home, smart building, smart city, smart car, networking car, healthcare, digital education, smart retail, security and security services. A method performed by a terminal in a wireless communication system is provided. The method comprises the following steps: receiving configuration information for Physical Downlink Control Channel (PDCCH) monitoring; based on the configuration information, identifying a monitoring opportunity related to a first PDCCH candidate and a second PDCCH candidate for first Downlink Control Information (DCI) format detection and a monitoring opportunity related to a third PDCCH candidate for second DCI format detection; and performing PDCCH monitoring based on the identifying. In case that one of the first and second PDCCH candidates overlaps with the third PDCCH candidate, the third PDCCH candidate is not counted to the blind decoding number.
Description
Technical Field
The present disclosure relates to operation of User Equipment (UE) and base stations in a wireless communication system. More particularly, the present disclosure relates to a method of configuring repeated transmission and reception of downlink control information in a wireless communication system, and an apparatus capable of performing the method.
Background
In order to meet the increasing wireless data traffic demands since the deployment of 4G communication systems, efforts have been made to develop improved 5G or quasi 5G communication systems. Therefore, a 5G or quasi 5G communication system is also referred to as a "super 4G network" or a "LTE-after-system". A 5G communication system is considered to be implemented in a higher layer frequency (millimeter wave) band (e.g., 60GHz band) to achieve higher data rates. In order to reduce propagation loss of radio waves and increase transmission distance, beamforming, massive Multiple Input Multiple Output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, massive antenna techniques are discussed in 5G communication systems. In addition, in the 5G communication system, development of improvement of a system network based on an advanced small cell, a cloud Radio Access Network (RAN), an ultra dense network, device-to-device (D2D) communication, a wireless backhaul, a mobile network, cooperative communication, cooperative multipoint (CoMP), reception-side interference cancellation, and the like is underway. In 5G systems, hybrid FSK and QAM modulation (FQAM) as Advanced Code Modulation (ACM) and Sliding Window Superposition Coding (SWSC) have been developed, as well as Filter Bank Multicarrier (FBMC), non-orthogonal multiple access (NOMA) and Sparse Code Multiple Access (SCMA) as advanced access techniques.
The internet is a human-centric connectivity network that human generates and consumes information, now evolving to the internet of things (IoT) in which distributed entities such as things exchange and process information without human intervention. A web of everything combining IoT technology and big data processing technology through a connection with a cloud server has emerged. As IoT implementations require technical elements such as "sensing technology," "wired/wireless communication and network infrastructure," "service interface technology," and "security technology," sensor networks, machine-to-machine (M2M) communications, machine-type communications (MTC), etc. have recently been studied. Such IoT environments may provide intelligent internet technology services that create new value for human life by collecting and analyzing data generated between connections. Through the convergence and combination between existing Information Technology (IT) and various industrial applications, ioT may be applied in a variety of fields including smart homes, smart buildings, smart cities, smart cars or networked cars, smart grids, healthcare, smart appliances, and advanced medical services.
Accordingly, various attempts have been made to apply 5G communication systems to IoT networks. For example, techniques such as sensor networks, machine Type Communications (MTC), and machine-to-machine (M2M) communications may be implemented by beamforming, MIMO, and array antennas. Applications of the cloud Radio Access Network (RAN) as the big data processing technology described above may also be regarded as examples of convergence between 5G technology and IoT technology.
Disclosure of Invention
[ technical problem ]
With the development of the above-described wireless communication system, various services can be provided, and thus a scheme for efficiently providing these services is required. Since the general method does not support repeated transmission of a Physical Downlink Control Channel (PDCCH), it is difficult to achieve a desired reliability in a scene requiring high reliability such as ultra-reliable low-latency communication (URLLC).
Technical scheme
The present disclosure may provide an apparatus and method capable of efficiently providing a service in a mobile communication system.
In an embodiment, a method performed by a terminal in a wireless communication system is provided. The method comprises the following steps: receiving configuration information for Physical Downlink Control Channel (PDCCH) monitoring; based on the configuration information, identifying a monitoring opportunity related to a first PDCCH candidate and a second PDCCH candidate for first Downlink Control Information (DCI) format detection and a monitoring opportunity related to a third PDCCH candidate for second DCI format detection; and performing PDCCH monitoring based on the identifying. In case that one of the first and second PDCCH candidates overlaps with the third PDCCH candidate, the third PDCCH candidate is not counted to the blind decoding number.
In an embodiment, a terminal in a wireless communication system is provided. The terminal includes a transceiver and a controller. The controller is configured to: receiving configuration information for Physical Downlink Control Channel (PDCCH) monitoring via a transceiver; based on the configuration information, identifying a monitoring opportunity related to a first PDCCH candidate and a second PDCCH candidate for first Downlink Control Information (DCI) format detection and a monitoring opportunity related to a third PDCCH candidate for second DCI format detection; and performing PDCCH monitoring based on the identifying. In case that one of the first and second PDCCH candidates overlaps with the third PDCCH candidate, the third PDCCH candidate is not counted to the blind decoding number.
[ advantageous effects ]
According to embodiments of the present disclosure, reception reliability of downlink control information may be effectively improved via a plurality of transmission points (TRPs) in a mobile communication system.
Drawings
The foregoing and other aspects, features, and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings in which:
fig. 1 illustrates a basic structure of a time-frequency domain in a wireless communication system according to an embodiment of the present disclosure;
Fig. 2 illustrates a frame, subframe, and slot structure in a wireless communication system according to an embodiment of the present disclosure;
fig. 3 shows an example of a configuration of a bandwidth part in a wireless communication system according to an embodiment of the present disclosure;
fig. 4 illustrates an example of a configuration of a control resource set of a downlink control channel in a wireless communication system according to an embodiment of the present disclosure;
fig. 5A illustrates a structure of a downlink control channel in a wireless communication system according to an embodiment of the present disclosure;
fig. 5B illustrates a case where multiple PDCCH monitoring opportunities may be present within a slot by a span UE in a wireless communication system according to an embodiment of the present disclosure;
fig. 6 illustrates an example of DRX operation in a wireless communication system according to an embodiment of the present disclosure;
fig. 7 illustrates an example of base station beam allocation according to TCI state configuration in a wireless communication system according to an embodiment of the present disclosure;
fig. 8 illustrates an example of a TCI state allocation method for a PDCCH in a wireless communication system according to an embodiment of the present disclosure;
fig. 9 illustrates a TCI indication MAC CE signaling structure for PDCCH DMRS in a wireless communication system according to an embodiment of the present disclosure;
Fig. 10 illustrates an example of a CORESET and search space beam configuration in a wireless communication system in accordance with an embodiment of the present disclosure;
fig. 11 illustrates an example of frequency domain resource allocation of PDSCH in a wireless communication system according to an embodiment of the disclosure;
fig. 12 illustrates an example of time domain resource allocation of PDSCH in a wireless communication system according to an embodiment;
fig. 13 illustrates an example of time domain resource allocation according to subcarrier spacing of a data channel and a control channel in a wireless communication system according to an embodiment;
fig. 14 illustrates a protocol structure of a base station and a UE in a wireless communication system in a single cell, carrier aggregation, and dual connectivity scenario according to an embodiment of the present disclosure;
fig. 15 illustrates an example of antenna port configuration and resource allocation for cooperative communication in a wireless communication system according to an embodiment of the present disclosure;
fig. 16 shows an example of a configuration of Downlink Control Information (DCI) for cooperative communication in a wireless communication system according to an embodiment of the present disclosure;
fig. 17 shows a flowchart of UE capability reporting during PDCCH repetition transmission and UE operation according to PDCCH repetition transmission configuration and explicit connection configuration conditions of a base station according to an embodiment of the present disclosure;
Fig. 18 shows a flowchart of UE capability reporting during PDCCH repetition transmission and base station operation according to a PDCCH repetition transmission configuration of a base station according to an embodiment of the present disclosure;
fig. 19 illustrates a structure of a UE in a wireless communication system according to an embodiment of the present disclosure; and is also provided with
Fig. 20 illustrates a structure of a base station in a wireless communication system according to an embodiment of the present disclosure.
Detailed Description
Before proceeding with the following detailed description, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms "include" and "comprise," as well as derivatives thereof, are intended to be inclusive and mean inclusion, but not limited to; the term "or" is inclusive, meaning and/or; the phrases "associated with … …" and "associated therewith" and derivatives thereof may mean included within … …, interconnected with … …, contained within … …, connected to or connected with … …, coupled to or coupled with … …, communicable with … …, cooperative with … …, interlaced, juxtaposed, proximate to … …, bound to or bound with … …, having … … properties, and the like; and the term "controller" means any device, system, or portion thereof that controls at least one operation, such device may be implemented in hardware, firmware, or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely.
In addition, the various functions described below may be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer readable program code. The phrase "computer readable program code" includes any type of computer code, including source code, object code, and executable code. The phrase "computer readable medium" includes any type of medium capable of being accessed by a computer, such as Read Only Memory (ROM), random Access Memory (RAM), a hard disk drive, a Compact Disc (CD), a Digital Video Disc (DVD), or any other type of memory. "non-transitory" computer-readable media exclude wired, wireless, optical, or other communication links that transmit transient electrical signals or other signals. Non-transitory computer readable media include media that can permanently store data, as well as media that can store data and subsequently rewrite the data, such as rewritable optical disks or erasable memory devices.
Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.
The figures 1 through 20, discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will appreciate that the principles of the present disclosure may be implemented in any suitably arranged system or apparatus.
Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
In describing embodiments of the present disclosure, descriptions related to technical contents well known in the art and not directly associated with the present disclosure will be omitted. Unnecessary description is omitted so as to prevent obscuring the main idea of the present disclosure and to more clearly communicate the main idea.
For the same reasons, in the drawings, some elements may be exaggerated, omitted, or schematically shown. In addition, the size of each element does not fully reflect the actual size. In the drawings, identical or corresponding elements have identical reference numerals.
Advantages and features of the present disclosure and methods of accomplishing the same may become apparent by reference to the following detailed description of embodiments taken in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments set forth below, but may be embodied in a variety of different forms. The following embodiments are provided solely for the purpose of fully disclosing the present disclosure and informing those skilled in the art the scope of the present disclosure and are limited only by the scope of the appended claims. The same or similar reference numbers will be used throughout the specification to refer to the same or similar elements. In describing the present disclosure, a detailed description of known functions or configurations incorporated herein will be omitted when it may be determined that the description may make the subject matter of the present disclosure unnecessarily unclear. The terms to be described below are terms defined in consideration of functions in the present disclosure, and may be different according to users, intention of users, or custom. Accordingly, the definition of terms should be determined based on the contents throughout the 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 enode B, a node B, a Base Station (BS), a radio access unit, a base station controller, and a node on a network. A terminal may include a User Equipment (UE), a Mobile Station (MS), a cellular telephone, a smart phone, a computer, or a multimedia system capable of performing communication functions. In the present disclosure, "Downlink (DL)" refers to a radio link via which a base station transmits signals to a terminal, and "Uplink (UL)" refers to a radio link via which a terminal transmits signals to a base station. In addition, in the following description, an LTE or LTE-a system may be described by way of example, but embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. Examples of such communication systems may include 5 th generation mobile communication technologies (5G, new radio and NR) that evolve beyond LTE-a, and in the following description, "5G" may be a concept that encompasses existing LTE, LTE-a or other similar services. In addition, embodiments of the present disclosure may also be applied to other communication systems with some modifications, based on the judgment of those skilled in the art, without departing significantly from the scope of the present disclosure.
Herein, it will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart block or blocks. These computer program instructions may also be stored in a computer-usable or computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-usable or computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the flowchart block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.
Additionally, each block of the flowchart illustrations may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.
As used herein, "unit" refers to a software element or a hardware element, such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), that performs a predetermined function. However, the "unit" does not always have a meaning limited to software or hardware. The "unit" may be configured to be stored in an addressable storage medium or to execute one or more processors. Thus, a "unit" includes, for example, software elements, object-oriented software elements, class elements or task elements, procedures, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and parameters. The elements and functions provided by a "unit" may be combined into a fewer number of elements or "units" or divided into a greater number of elements or "units". In addition, the elements and "units" may be implemented as one or more CPUs within a reproduction device or a secure multimedia card. In addition, a "unit" in an embodiment may include one or more processors.
Wireless communication systems have evolved from wireless communication systems providing voice center services to broadband wireless communication systems providing high speed, high quality packet data services, such as High Speed Packet Access (HSPA), long term evolution of 3GPP (LTE or evolved universal terrestrial radio access (E-UTRA)), LTE-advanced (LTE-a) and LTE-Pro, high Rate Packet Data (HRPD) and Ultra Mobile Broadband (UMB) of 3GPP2, and the communication standards of 802.16E of IEEE.
LTE systems, which are representative examples of broadband wireless communication systems, have adopted an Orthogonal Frequency Division Multiplexing (OFDM) scheme in the Downlink (DL) and a single carrier frequency division multiple access (SC-FDMA) scheme in the Uplink (UL). UL refers to a radio link through which a terminal (user equipment (UE) or Mobile Station (MS)) transmits data or control signals to a base station (BS or eNodeB), and DL refers to a radio link through which a base station transmits data or control signals to a terminal. The above-described multiple access scheme generally allocates and operates time-frequency resources including data or control information to be transmitted according to each other to prevent the time-frequency resources from overlapping each other, i.e., establishes orthogonality for distinguishing the data or control information of each user.
As a future communication system after the LTE system, the 5G communication system must be able to freely reflect various demands of users and service providers, and thus it is necessary to simultaneously support services satisfying the various demands. Services considered by 5G communication systems include enhanced mobile broadband (emmbb), mass machine type communication (mctc), ultra reliable low delay communication (URLLC), and the like.
The emmbb is intended to provide a higher data transmission rate than that supported by LTE, LTE-a or LTE-Pro. For example, in a 5G communication system, from the perspective of one base station, an eMBB should be able to provide a peak data rate of 20Gbps in DL and 10Gbps in UL. In addition, the 5G communication system should provide an increased user perceived terminal data rate when providing a peak data rate. To meet such needs, improvements in various transmission/reception techniques are needed, including further improved Multiple Input Multiple Output (MIMO) transmission techniques. In addition, a transmission bandwidth of up to 20MHz is used to transmit signals in a 2GHz band used by LTE, but a 5G communication system uses a bandwidth wider than 20MHz in a frequency band of 3GHz to 6GHz or more than 6GHz, thereby satisfying a data transmission rate required for the 5G communication system.
Meanwhile, mctc is considered to support application services, such as internet of things (IoT) in 5G communication systems. mctc is needed for access support for large-scale terminals in a cell, coverage enhancement of terminals, improved battery time, and cost reduction of terminals to effectively provide IoT. IoT is attached to various sensors and devices to provide communication power when it is attached to It is sometimes desirable to be able to support a large number of terminals in a cell (e.g., 1,000,000 terminals/km 2 ). In addition, since the terminal supporting mctc is likely to be located in a shadow area where a cell is not covered, such as a basement of a building, due to the nature of the service, the terminal requires a wider coverage area than other services provided by the 5G communication system. Terminals supporting mctc should be configured as inexpensive terminals and require very long battery life, such as 10 to 15 years, since the battery of the terminal is difficult to replace frequently.
Finally, URLLC is a cellular-based wireless communication service for mission critical purposes. For example, URLLC may be considered a service for use in remote control of robots or machines, industrial automation, unmanned aerial vehicles, remote healthcare, or emergency alerts. Thus, the communication provided by URLLC should provide very low latency and very high reliability. For example, services supporting URLLC need to meet air interface delays of less than 0.5 milliseconds and at the same time include a pair of 10 -5 Or smaller packet error rate requirements. Thus, for services supporting URLLC, a 5G system may be required to provide a shorter Transmission Time Interval (TTI) than other services, while ensuring a reliable communication link by allocating extensive resources in the frequency band.
The three services considered in the above 5G communication system (i.e., emmbb, URLLC, and mctc) may be multiplexed in one system and may be transmitted. Here, the service may use different transmission/reception methods and transmission/reception parameters in order to satisfy different demands. However, 5G is not limited to the above three services.
[ NR time-frequency resource ]
Hereinafter, a frame structure of the 5G system will be described in more detail with reference to the accompanying drawings.
Fig. 1 illustrates a basic structure of a time-frequency domain, which is a radio resource domain in which data or control channels are transmitted in a 5G system.
Referring to fig. 1, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. In the time-frequency domain, a basic unit of resource may be a Resource Element (RE) 101. The resource element 101 may be formed by 1 orthogonal frequency division multiplexing (OFDM) symbol 102 and is defined by 1 subcarrier 103 in the frequency domain. In the frequency domain of the power supply,(e.g., 12) consecutive REs may configure one Resource Block (RB) 104.
Fig. 2 shows a slot structure considered in a 5G system.
Referring to fig. 2, an example of the structure of a frame 200, a subframe 201, and a slot 202 is shown. One frame 200 may be defined as 10ms. One subframe 201 may be defined as 1ms, and thus one frame 200 may be configured by a total of 10 subframes 201. One slot 202 or 203 may be defined as 14 OFDM symbols (i.e., the number of symbols for one slot One subframe 201 may include one or more slots 202 and 203, and the number of slots 202 and 203 in each subframe 201 may be different according to a configuration value μ 204 or 205 for a subcarrier spacing. In the example of fig. 2, the case where the subcarrier spacing configuration values are μ=0 (indicated by reference numeral 204) and μ=1 (indicated by reference numeral 205) is shown. If μ=0 (indicated by reference numeral 204), one subframe 201 may include one slot 202; and if μ=1 (indicated by reference numeral 205), one subframe 201 may include two slots 203. That is, the number of slots in each subframeMay be different according to the subcarrier spacing configuration values μ, and thus the number of slots in each frameMay be different. Configuring μ, +.>And->Can be defined in table 1 below.
TABLE 1
Bandwidth portion (BWP)
Next, a configuration of a bandwidth part (BWP) in the 5G communication system will be described in detail with reference to the accompanying drawings.
Fig. 3 shows an example of a configuration regarding BWP in a 5G communication system.
Referring to fig. 3, an example is shown in which UE bandwidth 300 is configured by two BWP (i.e., bwp#1 and bwp#2) 302. The base station may configure one or more BWPs for the UE and may configure information as shown in table 2 below for each bandwidth part.
TABLE 2
Embodiments of the present disclosure are not limited to the above examples, and various parameters related to BWP may be configured in the UE in addition to configuration information, and some information may be omitted. The information may be transmitted by the base station to the UE via higher layer signaling (e.g., radio Resource Control (RRC) signaling). At least one BWP of the configured one or more BWP may be activated. Whether or not the configured BWP is activated may be semi-statically transmitted from the base station to the UE via RRC signaling, or may be dynamically transmitted through Downlink Control Information (DCI).
According to some embodiments, before a Radio Resource Control (RRC) connection, a UE may be configured with an initial bandwidth part (BWP) for initial access from a base station through a Master Information Block (MIB). More specifically, the UE may receive configuration information on a search space and a control resource set (CORESET), through which a PDCCH for receiving system information required for initial access may be transmitted through the MIB in an initial access operation, and the system information may correspond to remaining system information (RMSI) or system information block 1 (SIB 1). The control resource set (CORESET) and the search space configured by the MIB can be regarded as an Identification (ID) 0, respectively. The base station may notify the UE of configuration information such as frequency allocation information, time allocation information, and a data method of the control resource set #0 through the MIB. In addition, the base station may notify the UE of configuration information on the monitoring period and timing of the control resource set #0, i.e., configuration information on the search space #0, through the MIB. The UE may consider the frequency domain configured with the control resource set #0 obtained from the MIB as an initial BWP for initial access. Here, the Identifier (ID) of the initial BWP may be regarded as zero.
The configuration of 5G supported BWP may be used for various purposes.
According to some embodiments, the case where the bandwidth supported by the UE is smaller than the system bandwidth may be supported by a BWP configuration. For example, the base station configures a frequency location (configuration information 2) of BWP in the UE so that the UE can transmit or receive data at a specific frequency location within the system bandwidth.
In addition, according to some embodiments, the base station may configure multiple BWP in the UE for the purpose of supporting different parameter sets. For example, in order to support both transmitting data to and receiving data from a predetermined UE by using a subcarrier spacing of 15kHz and a subcarrier spacing of 30kHz, two BWPs may be configured to use a subcarrier spacing of 15kHz and a subcarrier spacing of 30kHz, respectively. The different BWP may be frequency division multiplexed, and when attempting to transmit or receive data at a specific subcarrier interval, the BWP configured with the corresponding subcarrier interval may be activated.
In addition, according to some embodiments, the base station may configure BWP with different bandwidth sizes in the UE for the purpose of reducing power consumption of the UE. For example, when a UE supports a very large bandwidth (e.g., a bandwidth of 100 MHz) and always transmits/receives data with a corresponding bandwidth, transmission or reception may cause very high power consumption in the UE. In particular, when the UE performs unnecessary downlink control channel monitoring for a large bandwidth of 100MHz even when there is no traffic, it may be very inefficient in terms of power consumption. Thus, in order to reduce power consumption of the UE, the base station may configure the UE with a relatively small bandwidth BWP, for example, a 20MHz BWP. In the absence of traffic, the UE may perform a monitoring operation on the BWP of 20 MHz. When data to be transmitted or received occurs, the UE may transmit or receive data in BWP of 100MHz according to an indication of the base station.
In the method of configuring the BWP, the UE may receive configuration information of an initial bandwidth part through a Master Information Block (MIB) in an initial connection operation before RRC connection. More specifically, the UE may be configured with a control resource set (CORESET) for a downlink control channel, through which Downlink Control Information (DCI) for scheduling a System Information Block (SIB) may be transmitted from a MIB of a Physical Broadcast Channel (PBCH). The bandwidth of the control resource set configured through the MIB may be regarded as an initial BWP. The UE may receive a Physical Downlink Shared Channel (PDSCH) for transmitting SIBs through the configured initial BWP. The initial BWP may be used for Other System Information (OSI), paging and random access, and reception of SIBs.
Bandwidth portion (BWP) handoff
When one or more BWP have been configured to the UE, the base station may instruct the UE to change (or switch, transform) the BWP by using the bandwidth part indicator field in the DCI. As an example, in fig. 3, when the BWP currently activated by the UE is bwp#1 301, the base station may indicate bwp#2302 to the UE by using the BWP indicator in the DCI, and the UE may perform BWP handover to bwp#2302, the bwp#2302 being indicated by the BWP indicator in the received DCI.
As described above, since the DCI-based BWP change may be indicated by the DCI scheduling the PDSCH or PUSCH, when a request for switching BWP is received, the UE should smoothly receive or transmit the PDSCH or PUSCH scheduled by the DCI in the switched BWP without difficulty. For this purpose, the standard specifies the delay time (T BWP ) The requirements may be defined, for example, as shown in table 3 below.
TABLE 3
The requirement for BWP handover delay time supports either type 1 or type 2 depending on UE capabilities. The UE may report supportable BWP delay time types to the base station.
When the UE receives DCI including a BWP switch indicator in slot n according to a requirement for a BWP switch delay time, the UE may be not later than slot n+t BWP To a new BWP indicated by the BWP switch indicator, and may perform transmission and reception of a data channel scheduled by the corresponding DCI in the switched new BWP. When the base station intends to schedule the data channel to the new BWP, the base station may perform a handoff by considering the BWP handoff delay time (T BWP ) To determine the time domain resource allocation of the data channel. That is, when the base station schedules a data channel to a new BWP, the base station may schedule the corresponding data channel after a BWP switch delay time according to a method for determining time domain resource allocation of the data channel. Thus, the UE may not expect the DCI indicating BWP handover to indicate less than the BWP handover delay time (T BWP ) Is set to the slot offset (K0 or K2) value.
If the UE receives DCI (e.g., DCI format 1_1 or 0_1) indicating a BWP handover, the UE may not perform transmission or reception during a time interval from a third symbol in a slot in which a PDCCH including the DCI is received to a slot start time indicated by a slot offset (K0 or K2) value indicated by a time domain resource allocation indicator field in the DCI. For example, if the UE receives DCI indicating a BWP handover in the slot n and the slot offset value indicated by the DCI is K, the UE may not perform transmission or reception from the third symbol in the slot n to the symbol before the slot n+k (i.e., the last symbol of the slot n+k-1).
[ SS/PBCH Block ]
Next, a Synchronization Signal (SS)/PBCH block in 5G will be described.
The SS/PBCH block may refer to a physical layer channel block including a primary SS (PSS), a Secondary SS (SSs), and a PBCH. Specifically, the SS/PBCH blocks are as follows:
PSS: a signal that serves as a reference for downlink time/frequency synchronization and provides some information of the cell ID.
SSS: serve as a reference for downlink time/frequency synchronization, and provide a signal of remaining cell ID information not provided by the PSS. In addition, SSS may be used as a reference signal for PBCH demodulation.
PBCH: channels for transmitting or receiving basic system information required for a data channel and a control channel of a UE are provided. The basic system information may include search space related control information indicating radio resource mapping information of the control channel, control information of a separate data channel scheduled for transmitting the system information, and the like.
The SS/PBCH block includes a combination of PSS, SSs and PBCH. One or more SS/PBCH blocks may be transmitted within 5ms, and each of the transmitted SS/PBCH blocks may be distinguished by an index.
The UE may detect PSS and SSS in an initial access operation and may decode PBCH. The UE may obtain MIB from the PBCH and may be configured with a control resource set (CORESET) #0 (which may correspond to a control resource set with CORESET index 0). Assuming that the demodulation reference signal (DMRS) transmitted in the control resource set #0 is quasi co-located (QCLed) at the selected SS/PBCH block, the UE may monitor the control resource set #0. The UE may receive system information based on the downlink control information transmitted by the control resource set #0. The UE may obtain configuration information related to a Random Access Channel (RACH) required for initial access from the received system information. The UE may transmit a Physical RACH (PRACH) to the base station by considering the selected SS/PBCH index, and the base station receiving the PRACH may obtain information about the SS/PBCH block index selected by the UE. The base station may know which block the UE selected among SS/PBCH blocks and may know that the control resource set #0 associated therewith is monitored.
[DRX]
Fig. 6 illustrates Discontinuous Reception (DRX).
Discontinuous Reception (DRX) is an operation in which a UE using a service discontinuously receives data in an RRC connected state in which a radio link is established between a base station and the UE. When DRX is applied, the UE turns on the receiver at a certain point in time to monitor the control channel and turns off the receiver when no data is received for a predetermined period, and thus power consumption of the UE can be reduced. DRX operation may be controlled by the MAC layer device based on various parameters and timers.
Referring to fig. 6, the active time 605 is a time when the UE wakes up every DRX cycle and monitors the PDCCH. The activity time 605 may be defined as follows.
The drx-onDurationTimer, drx-InactivityTimer, drx-RetransmissionTimerDL, drx-retransmission timer UL or ra-ContentionResoltionTimer is running;
the scheduling request is transmitted on PUCCH and in progress; or alternatively
After successful random access response to a random access preamble not selected by the MAC entity among the contention-based random access preambles, a PDCCH indicating a new transmission of the C-RNTI addressed to the MAC entity has not been received.
The drx-onDurationTimer, drx-activity Timer, drx-RetransmissionTimerDL, drx-RetransmissionTimerUL, ra-contentioresolutiontimer, etc. are timers whose values are configured by the base station, and have a function of configuring the UE to monitor the PDCCH if a predetermined condition is satisfied.
The DRX-onduration timer 615 is a parameter used to configure the minimum time the UE is awake in the DRX cycle. The drx-incavitytimer 620 is a parameter for configuring a time when the UE is additionally awake when receiving a PDCCH indicating a new UL transmission or DL transmission (indicated by reference numeral 630). drx-retransmission timerdl is a parameter for configuring the maximum time the UE is awake to receive DL retransmission in DL HARQ process. drx-retransmission timer UL is a parameter for configuring the maximum time the UE is awake to receive UL retransmission grant in UL HARQ process. The drx-onDurationTimer, drx-InactivityTimer, drx-retransmission timerdl and drx-retransmission timersl may be configured as, for example, time, the number of subframes, the number of slots, and the like. ra-contentioresolutiontimer is a parameter for monitoring PDCCH during random access.
The inactive time 610 is a time configured to not monitor the PDCCH and/or a time configured to not receive the PDCCH during the DRX operation, and the remaining time except the active time 605 among the entire time in which the DRX operation is performed may become the inactive time 610. When the PDCCH is not monitored for an active time 605, the UE may enter a sleep or inactive state to reduce power consumption.
The DRX cycle refers to a period in which the UE wakes up and monitors the PDCCH. That is, the DRX cycle refers to an occurrence period or time interval of a duration until the UE monitors the PDCCH and then monitors the next PDCCH. There are two types of DRX cycles, namely a short DRX cycle and a long DRX cycle. A short DRX cycle may optionally be applied.
The long DRX cycle 625 is a longer cycle between two DRX cycles configured in the UE. When operating in long DRX, the UE starts the DRX-onduration timer 615 again after a time of the long DRX cycle 625 from the start point (e.g., start symbol) of the DRX-onduration timer 615. When operating in the long DRX cycle 625, the UE may start the DRX-onduration timer 615 in a slot after DRX-SlotOffset in a subframe satisfying the following equation 1. The drx-SlotOffset refers to the delay before the drx-onduration timer 615 starts. The drx-SlotOffset may be configured as, for example, time, number of slots, etc.
[ equation 1]
[ (SFN x 10) +number of subframes ] module (drx-LongCycle) =drx-StartOffset
Here, DRX-longcyclestatoffset may include a long DRX cycle 625 and DRX-StartOffset, and may be used to define subframes that start the long DRX cycle 625. The drx-longcycletartoffset may be configured as, for example, time, the number of subframes, the number of slots, etc.
[PDCCH：DCI]
Next, downlink Control Information (DCI) in the 5G system will be described in detail.
In a 5G system, scheduling information regarding uplink data (or Physical Uplink Shared Channel (PUSCH) or downlink data (or Physical Downlink Shared Channel (PDSCH)) may be monitored by a UE and a fallback DCI format regarding PUSCH or PDSCH through DCI from a base station.
The DCI may be transmitted through a PDCCH (i.e., a physical downlink control channel) after being performed with channel coding and modulation. A Cyclic Redundancy Check (CRC) may be attached to the DCI message payload, and the CRC may be scrambled by a Radio Network Temporary Identifier (RNTI) corresponding to the UE identification information. Depending on the purpose of the DCI message (e.g., UE-specific data transmission, power adjustment command, or random access response), different RNTIs may be used. That is, the RNTI is included in the CRC calculation process and then transmitted, not explicitly transmitted. When receiving the DCI message transmitted through the PDCCH, the UE may check the CRC by using the allocated RNTI. When the CRC check result is correct, the UE may know that the corresponding message has been transmitted to the UE.
For example, DCI for PDSCH scheduling System Information (SI) may be scrambled by SI-RNTI. DCI for scheduling PDSCH of a Random Access Response (RAR) message may be scrambled by RA-RNTI. The DCI of the PDSCH for scheduling the paging message may be scrambled by the P-RNTI. The DCI for informing the Slot Format Indicator (SFI) may be scrambled by the SFI-RNTI. The DCI for informing the Transmit Power Control (TPC) may be scrambled by a TPC-RNTI. The DCI for scheduling the UE-specific PDSCH or PUSCH may be scrambled by a cell RNTI (C-RNTI).
DCI format 0_0 may be used as a backoff DCI for scheduling PUSCH. Here, the CRC may be scrambled by the C-RNTI. The DCI format 0_0 with CRC scrambled by the C-RNTI may include, for example, information such as Table 4 below.
TABLE 4
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DCI format 0_1 may be used as non-fallback DCI for scheduling PUSCH. Here, the CRC may be scrambled by the C-RNTI. The DCI format 0_1 with CRC scrambled by the C-RNTI may include the information of Table 5 below.
TABLE 5
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DCI format 1_0 may be used as a fallback DCI for scheduling PDSCH. Here, the CRC may be scrambled by the C-RNTI. The DCI format 1_0 in which the CRC is scrambled by the C-RNTI may include the following information as in table 6 below.
TABLE 6
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DCI format 1_1 may be used as non-fallback DCI for scheduling PDSCH. Here, the CRC may be scrambled by the C-RNTI. The DCI format 1_1 in which the CRC is scrambled by the C-RNTI may include the information of table 7 below.
TABLE 7
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[ PDCCH: CORESET, REG, CCE search space ]
Hereinafter, a downlink control channel in a 5G communication system will be described in more detail with reference to the accompanying drawings.
Fig. 4 illustrates an example of a control resource set (CORESET) for transmitting a downlink control channel in a 5G wireless communication system. Fig. 4 shows an example in which a UE BWP 410 is configured in the frequency domain and two control resource sets (control resource set #1 401 and control resource set #2 420) are configured in one slot 402 in the time domain. The control resource sets 401 and 402 may be configured in specific frequency resources 403 within the entire UE BWP 410 in the frequency domain. The control resource set may be configured with one or more OFDM symbols in the time domain and this may be defined as a control resource set duration 404. Referring to the example shown in fig. 4, control resource set #1 401 is configured with a control resource set duration of two symbols, and control resource set #2 402 is configured with a control resource set duration of one symbol.
The above-described control resource set in 5G may be configured to the UE by the base station via higher layer signaling (e.g., system information, master Information Block (MIB), radio Resource Control (RRC) signaling). Configuring the control resource set to the UE may be understood as providing information such as control resource set identification, frequency location of the control resource set, symbol length of the control resource set, etc. These configuration information may include the information of table 8 below.
TABLE 8
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In table 8, TCI-StatesPDCCH (abbreviated as Transmit Configuration Indication (TCI) state) configuration information may include information about one or more Synchronization Signal (SS)/Physical Broadcast Channel (PBCH) block (i.e., synchronization Signal Block (SSB)) indexes or channel state information reference signal (CSI-RS) indexes in quasi co-ordination relation with DMRS transmitted in a corresponding control resource set.
Fig. 5A shows an example of a basic unit of time-frequency resources configuring a downlink control channel that can be used in 5G. Referring to fig. 5A, a basic unit of time-frequency resources configuring a control channel may be referred to as a Resource Element Group (REG) 503.REG 503 may be defined by one OFDM symbol 501 in the time domain and one Physical Resource Block (PRB) 502 (i.e., 12 subcarriers) in the frequency domain. The base station may concatenate REGs 503 to configure the downlink control channel allocation units.
As shown in fig. 5A, when the basic unit allocated to the downlink control channel in 5G is a Control Channel Element (CCE) 504, one CCE 504 may include a plurality of REGs 503. When the REGs 503 shown in fig. 5A are described as examples, the REGs 503 may include 12 Resource Elements (REs), and when one CCE 504 includes six REGs 503, one CCE 504 may include 72 REs. When configuring a set of downlink control resources, a corresponding region may include a plurality of CCEs 504. A particular downlink control channel may be transmitted after being mapped to one or more CCEs 504 according to an Aggregation Level (AL) in the control resource set. CCEs 504 in the control resource set are distinguished by labels. Here, the number of CCEs 504 may be allocated according to a logical mapping scheme.
Referring to fig. 5A, a basic unit of a downlink control channel (i.e., REG 503) may include REs to which DCI is mapped and regions to which DMRS 505, which is a reference signal for decoding the DCI, is mapped. As shown in fig. 5A, three DMRSs 505 may be transmitted in one REG 503. The number of CCEs required to transmit the PDCCH may be 1, 2, 4, 8, or 16 depending on an Aggregation Level (AL). Different numbers of CCEs may be used to implement link adaptation of the downlink control channel. For example, if al=l, one downlink control channel may be transmitted through L CCEs. The UE needs to detect the signal in a state where the UE does not know information related to the downlink control channel, and a search space indicating a set of CCEs has been defined for blind decoding. The search space is a set of candidate downlink control channels including CCEs that the UE must attempt to decode at a given AL. Since there are various ALs that have 1, 2, 4, 8 or 16 CCEs constitute one bundle, the UE may have a plurality of search spaces. The set of search spaces may be defined as the set of search spaces under all configured ALs.
The search space may be classified into a common search space and a UE-specific search space. A predetermined group of UEs or all UEs may check a common search space of the PDCCH to receive cell common control information such as dynamic scheduling of system information or paging messages. For example, PDSCH scheduling allocation information for transmitting SIBs, including cell operator information, etc., may be received by checking a common search space of the PDCCH. In the case of a common search space, since a predetermined UE group or all UEs need to receive PDCCHs, the common search space may be defined as a previously designated set of CCEs. Scheduling allocation information regarding the UE-specific PDSCH or PUSCH may be received by checking the UE-specific search space of the PDCCH. The UE-specific search space may be defined UE-specifically based on the UE identity and various system parameters.
In 5G, parameters for the search space of the PDCCH may be configured to the UE by the base station via higher layer signaling (e.g., SIB, MIB, and RRC signaling). For example, the base station may configure the number of PDCCH candidate sets at each aggregation level L in the UE, the monitoring periodicity of the search space, the monitoring occasions of symbol units in slots of the search space, the search space type (common search space or UE-specific search space), a combination of RNTI and DCI formats to be monitored in the search space, a control resource set index for monitoring the search space, and the like. For example, the configuration information of the search space for the PDCCH may include the following information of table 9 below.
TABLE 9
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The base station may configure one or more search space sets for the UE according to the configuration information. According to some embodiments, the base station may configure search space set 1 and search space set 2 in the UE. The base station may configure search space set 1 in the UE such that DCI format a scrambled by the X-RNTI is monitored in the common search space. The base station may configure search space set 2 in the UE such that DCI format B scrambled by Y-RNTI is monitored in the UE-specific search space.
Depending on the configuration information, there may be one or more sets of search spaces in a common search space or a UE-specific search space. For example, search space set #1 and search space set #2 may be configured as a common search space, and search space set #3 and search space set #4 may be configured as UE-specific search spaces.
In the common search space, the following combination of DCI format and RNTI may be monitored. However, the present disclosure is not limited thereto.
-DCI format 0_0/1_0 with CRC scrambled by C-RNTI, CS-RNTI, SP-CSI-RNTI, RA-RNTI, TC-RNTI, P-RNTI, SI-RNTI;
-DCI format 2_0 with CRC scrambled by SFI-RNTI;
-DCI format 2_1 with CRC scrambled by INT-RNTI;
-DCI format 2_2 with CRC scrambled by TPC-PUSCH-RNTI, TPC-PUCCH-RNTI;
DCI format 2_3 with CRC scrambled by TPC-SRS-RNTI.
In the UE-specific search space, the following combination of DCI format and RNTI may be monitored. However, the present disclosure is not limited thereto.
-DCI format 0_0/1_0 with CRC scrambled by C-RNTI, CS-RNTI, TC-RNTI;
DCI format 1_0/1_1 with CRC scrambled by C-RNTI, CS-RNTI, TC-RNTI.
The specific RNTI may follow the definition and use described below:
C-RNTI (cell RNTI): for UE-specific PDSCH scheduling.
Temporary cell RNTI (TC-RNTI): for UE-specific PDSCH scheduling.
Configured scheduling RNTI (CS-RNTI): UE-specific PDSCH scheduling for semi-static configuration.
Random access RNTI (RA-RNTI): PDSCH scheduling in random access operation.
Paging RNTI (P-RNTI): PDSCH scheduling for transmitting pages.
System information RNTI (SI-RNTI): PDSCH scheduling for transmitting system information.
Interrupt RNTI (INT-RNTI): for informing whether to puncture PDSCH.
Transmit power adjustment of PUSCH RNTI (TPC-PUSCH-RNTI): a power adjustment command for indicating PUSCH.
Transmit power adjustment of PUCCH RNTI (TPC-PUCCH-RNTI): a power adjustment command for indicating PUCCH.
Transmit power adjustment of SRS RNTI (TPC-SRS-RNTI): a power adjustment command for indicating SRS.
The DCI format specified above may follow the definition shown in table 10 below.
TABLE 10
In 5G, the search space at the aggregation level L in the control resource set p and the search space set s may be represented by the following equation 2.
[ equation 2]
-L: aggregation level
-n CI : carrier index
-N CCE，p : controlling the total number of CCEs present in a resource set p
-n μ s，f : time slot index
-M (L) p，s，max : number of candidate PDCCHs at aggregation level L
-m s ，nCI＝0，...，M (L) p，s，max -1: candidate PDCCH set index at aggregation level L
-i＝0、……、L -1
Y p，-1 ＝n RNTI ≠0，A p ＝39827for pmod3＝0，A p ＝39829for pmod3＝1，A p ＝39839for pmod3＝2，D＝65537
-n RNTI : UE identifier
The value may correspond to zero in the common search space.
In the case of a UE-specific search space,the value may correspond to a value that varies according to a UE identity (C-RNTI or ID configured by the base station for the UE) and a time index.
In 5G, multiple search space sets may be configured with different parameters (e.g., parameters in table 9), and thus, at each point in time, the set of search space sets monitored by the UE may be different. For example, if search space set #1 is configured with an X-slot period and search space set #2 is configured with a Y-slot period, and X and Y are different, the UE may monitor both search space set #1 and search space set #2 in a specific slot, and may monitor one of search space set #1 and search space set #2 in a specific slot.
[ PDCCH: scrambling code ID
Next, the scrambling code ID of the downlink control channel in the 5G system will be described in detail. The scrambling sequence generator of the downlink control channel may be initialized as shown in equation 3 below.
[ equation 3]
c init ＝(n RNTI ·2 16 +n ID )mod2 31
In equation 3, n in case of UE-specific search space ID Has an integer value between 0 and 65535, which is configured by pdcch-DMRS-scramblindrid as high-layer signaling, and if pdcch-DMRS-scramblindrid is not configured, n ID Having the same value as the cell ID. In case of the UE-specific search space in equation 3, if the pdcch-DMRS-scramblindrid is configured, n RNTI Having the same as C-RNTIAnd if the pdcch-DMRS-scramblindID is not configured, n RNTI Having a value of 0.
[ PDCCH DMRS: scrambling code ID
Next, the scrambling code ID of the DMRS of the downlink control channel in the 5G system will be described in detail. The scrambling sequence generator of the DMRS of the downlink control channel may be initialized as shown in the following equation 4.
[ equation 4]
In equation 4, N ID Has a value configured by the pdcch-DMRS-scramblindrid as high-layer signaling, and if the pdcch-DMRS-scramblindrid is not configured, n ID Having the same value as the cell ID. In the equation (4) for the case of the optical fiber, And l represents a slot index and an OFDM symbol index, respectively. It follows that the scrambling sequence of PDCCH DMRS is initialized for each slot and for each OFDM symbol.
[ PDCCH: span ]
For each subcarrier spacing, the UE may perform UE capability reporting for the case of having multiple PDCCH monitoring occasions in the slot, and in this case the term "span" may be used. "span" means that the UE can monitor consecutive symbols of the PDCCH in a slot, and each PDCCH monitoring occasion is within one span. The span may be denoted as (X, Y), where X denotes the minimum number of symbols that need to be separated between the first symbols of two consecutive spans, and Y denotes the number of consecutive symbols in one span that the UE can monitor the PDCCH. Here, the UE may monitor the PDCCH for an interval from the first symbol of the span to Y symbols within the span.
Fig. 5B illustrates a case in which a UE may have a plurality of PDCCH monitoring occasions within a slot by a span in a wireless communication system. Spans may be represented as (X, Y) = (7, 4), (4, 3) and (2, 2), and these three cases are indicated by reference numerals (5-1-00), (5-1-05) and (5-1-10), respectively, in fig. 5B. By way of example, (5-1-00) indicates the case where there are two spans in a slot that can be represented by (7, 4). The interval between the first symbols of two spans is denoted as x=7, the pdcch monitoring occasion may exist within a total of Y symbols (y=3) from the first symbol of each span, and the search spaces 1 and 2 may exist within Y symbols (y=3). As another example, (5-1-05) represents the following: a total of three spans exist in the time slot that may be represented as (4, 3), and the interval between the second span and the third span is shown separated by X 'symbols (X' =5) greater than x=4.
[ PDCCH: UE capability report ]
The slot positions where the above common search space and the UE-specific search space are located are indicated by the monitoringslot periodic and offset parameter in table 9, and the symbol positions in the slots are indicated by the bitmap by the monitoringsymbol width slot parameter in table 9. On the other hand, symbol positions where a UE in a slot can monitor a search space can be reported to a base station through the following UE capabilities.
UE capability 1 (hereinafter FG 3-1). As shown in table 11 below, this UE capability represents a UE capability that can monitor a common search space or a UE-specific search space for types 1 and 3 in the slot if one Monitor Occasion (MO) exists in the slot when the corresponding MO occasion is located within the first 3 symbols in the slot. This UE capability is a mandatory capability that all UEs supporting NR should support and does not explicitly report to the base station whether or not such capability is supported.
TABLE 11
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UE capability 2 (hereinafter FG 3-2). As shown in table 12 below, this UE capability represents the UE capability that can be monitored regardless of the start symbol position of the MO in the case where there is a monitor occasion (MO: monitor occasion) for the common search space or the UE-specific search space in the slot. Such UE capabilities may optionally be supported by the UE and explicitly report to the base station whether such capabilities are supported.
TABLE 12
UE capability 3 (hereinafter FG 3-5, 3-5a and 3-5 b). As shown in table 13 below, this UE capability indicates a Monitor Opportunity (MO) mode that the UE may monitor when there are multiple MO's in the slot for a common search space or a UE-specific search space. The pattern includes a spacing X between start symbols between different MOs and a maximum symbol length Y of one MO. The (X, Y) combinations supported by the UE may be one or more of { (2, 2), (4, 3) and (7, 3) }. Such UE capabilities are optionally supported by the UE and it is explicitly reported to the base station whether such capabilities are supported or not and the above-mentioned (X, Y) combination.
TABLE 13
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The UE may report to the base station whether UE capability 2 and/or UE capability 3 and related parameters described above are supported. The base station may perform time domain resource allocation of the common search space and the UE-specific search space based on the reported UE capabilities. When performing resource allocation, the base station may prevent the UE from locating the MO in an unmonitored location.
[ PDCCH: BD/CCE restriction ]
When configuring multiple search space sets for a UE, the following conditions may be considered in a method for determining a search space set configured to be monitored by the UE.
If the UE is configured to monitoringcapability config-r16 as higher layer signaling, which is r15monitoringcapability, the UE defines a maximum value of the number of monitorable candidate PDCCHs and the number of CCEs configuring the entire search space for each slot (here, the entire search space refers to the entire CCE set corresponding to the joint region of the plurality of search space sets). In addition, if the value of monitoringcapability config-r16 is configured as r16monitoringcapability, the UE defines a maximum value of the number of monitorable candidate PDCCHs and the number of CCEs configuring the entire search space for each span (here, the entire search space refers to the entire CCE set corresponding to the joint region of the plurality of search space sets).
[ condition 1: limiting the maximum number of PDCCH candidates
As described above, if the configuration value of the higher layer signaling is configured with 15.2 μ Defining on a time slot basis in a cell of a subcarrier spacing of kHz, then M μ That is, the maximum number of candidate PDCCH sets that the UE can monitor may be defined by the following table 14, and if defined based on span, mu may be defined by the following table 15.
TABLE 14
| μ | Waiting per time slot and per serving cellMaximum number of PDCCH selection (M μ ) |
| 0 | 44 |
| 1 | 36 |
| 2 | 22 |
| 3 | 20 |
TABLE 15
[ condition 2: limiting the maximum number of CCEs ]
As described above, if the configuration value of the higher layer signaling is configured with 15.2 μ Defining on a time slot basis in a cell of a subcarrier spacing of kHz, then C μ That is, the maximum number of CCEs configuring the entire search space (where the entire search space represents the entire CCE set corresponding to the joint region of the multiple search space sets) may be defined by the following Table 16, and if defined based on span, C μ May be defined by table 17 below.
TABLE 16
| μ | Maximum number of non-overlapping CCEs per slot and per serving cell (C μ ) |
| 0 | 56 |
| 1 | 56 |
| 2 | 48 |
| 3 | 32 |
TABLE 17
For convenience of description, a case where both the condition 1 and the condition 2 are satisfied at a specific point in time is defined as "condition a". Therefore, the condition a not being satisfied may mean that at least one of the above-described conditions 1 and 2 is not satisfied.
[ PDCCH: oversubscription
Depending on the configuration of the search space set of base stations, it may occur that condition a is not satisfied at a particular point in time. If the condition a is not satisfied at a specific point of time, the UE may select and monitor only some of the search space sets configured to satisfy the condition a at the corresponding point of time, and the base station may transmit the PDCCH to the selected search space set.
The method of selecting some search spaces from the entire set of configured search spaces may follow the following method.
If condition a of the PDCCH is not satisfied at a specific time point (slot), the UE (or the base station) may select a search space set of which a search space type is configured as a common search space from among search space sets existing at the corresponding time point, in preference to a search space set of which a search space type is configured as a UE-specific search space.
If all sets of search spaces configured as a common search space are selected (i.e., if condition a is satisfied even after all search spaces configured as a common search space are selected), the UE (or the base station) may select the sets of search spaces configured as having UE-specific search spaces. Here, if there are multiple search space sets configured to have a UE-specific search space, a search space set having a lower search space set index may have a higher priority. The UE-specific set of search spaces may be selected within the range that satisfies condition a in consideration of priority.
[ QCL, TCI State ]
In a wireless communication system, one or more different antenna ports (or different antenna ports may be replaced with one or more channels, signals, and combinations thereof, but in the following description of the present disclosure, collectively referred to as different antenna ports for ease of explanation) may be associated with each other through a quasi-co-location (QCL) configuration. The TCI state is used to declare a QCL relationship between the PDCCH (or PDCCH DMRS) and another RS or channel, and the particular reference antenna port (reference rs#a) and another target antenna port B (target rs#b) quasi-co-location representation allows the UE to apply some or all of the large-scale channel parameters estimated by antenna port a to channel measurements from antenna port B. Depending on the situation, QCL needs to be associated with different parameters such as 1) time tracking affected by average delay and delay spread, 2) frequency tracking affected by doppler shift and doppler spread, 3) Radio Resource Management (RRM) affected by average gain, and 4) Beam Management (BM) affected by spatial parameters. Thus, NR supports four types of QCL relationships, as shown in Table 18 below.
TABLE 18
| QCL type | Large scale characteristics |
| A | Doppler shift, doppler spread, average delay, delay spread |
| B | Doppler shift and Doppler spread |
| C | Doppler shift, average delay |
| D | Spatial Rx parameters |
The spatial RX parameters may collectively refer to some or all of various parameters, such as angle of arrival (AoA), power Angle Spectrum (PAS) of AoA, angle of departure (AoD), PAS of AoD, transmit/receive channel correlation, transmit/receive beamforming, and spatial channel correlation.
The QCL relationship may be configured for the UE through RRC parameters TCI-State and QCL-Info, as shown in table 19 below. Referring to table 19, the base station configures one or more TCI states for the UE and informs the UE of at most two QCL relationships (QCL-Type 1, QCL-Type 2) of RSs (i.e., target RSs) related to IDs of the TCI states. Here, the plurality of QCL information (QCL-Info) included in each TCL state includes a serving cell index and a BWP index of the reference RS indicated by the corresponding QCL information, a type and ID of the reference RS, and a QCL type as shown in table 18 above.
TABLE 19
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Fig. 7 illustrates an example of base station beam allocation according to TCI state configuration. Referring to fig. 7, the base station transmits information about N different beams to the UE through N different TCI states. For example, if n=3 as shown in fig. 7, the base station may allow the QCL-Type2 parameters included in the three TCI states 700, 705 and 710 to be associated with CSI-RS or SSB corresponding to different beams and configured with QCL Type D, and thus may provide notification relating to the antenna ports of the different TCI states 700, 705 and 710 being associated with different spatial Rx parameters (i.e., different beams).
Tables 20 to 24 below show the effective TCI state configuration according to the target antenna port type.
Table 20 shows an effective TCI state configuration when the target antenna port is CSI-RS (TRS) for tracking. TRS refers to NZP CSI-RS in which repetition parameters are not configured and TRS-Info is configured as true. Configuration 3 in table 20 can be used for aperiodic TRS.
TABLE 20
Table 21 shows an effective TCI state configuration when the target antenna port is a CSI-RS for CSI. CSI-RS for CSI refers to NZP CSI-RS in which a parameter indicating repetition (e.g., a repetition parameter) is not configured and trs-Info is not configured as true.
TABLE 21
Table 22 shows an effective TCI state configuration when the target antenna port is a CSI-RS for Beam Management (BM) that has the same meaning as the CSI-RS for L1 RSRP reporting. CSI-RS for BM refers to NZP CSI-RS among CSI-RS that are configured with repetition parameters and have on or off values and trs-Info is not configured as true.
TABLE 22
Table 23 shows the effective TCI state configuration when the target antenna port is PDCCH DMRS.
TABLE 23
Table 24 shows the effective TCI state configuration when the target antenna port is PDSCH DMRS.
TABLE 24
In the representative QCL configuration methods according to tables 20 to 24, the target antenna port and the reference antenna port for each stage are configured as "SSB" → "TRS" → "CSI-RS for CSI, CSI-RS for BM, PDCCH DMRS, or PDSCH DMRS". Thus, statistics that may be measured from the SSB and the TRS may be linked with each of the antenna ports to assist the UE in the receive operation.
[ PDCCH: TCI State ]
Specifically, TCI state combinations suitable for PDCCH DMRS antenna ports are shown in table 25 below. In table 25, the fourth row is a combination of assumptions by the UE before RRC configuration, and configuration after RRC is not possible.
TABLE 25
In NR, a hierarchical signaling method as shown in fig. 8 is supported to dynamically allocate PDCCH beams. Referring to fig. 8, a base station may configure N TCI states 805, 810, … …, and 820 for a UE via RRC signaling 800, and may configure some of the TCI states as TCI states of CORESET (indicated by reference numeral 825). Thereafter, the base station may indicate one of the TCI states 830, 835, and 840 of CORESET (indicated by reference numeral 845) to the UE via MAC CE signaling. Thereafter, the UE may receive the PDCCH based on beam information included in the TCI state indicated by the MAC CE signaling.
Fig. 9 shows the TCI indication MAC CE signaling structure for PDCCH DMRS. Referring to fig. 9, TCI for PDCCH DMRS indicates that MAC CE signaling is configured by 2 bytes (16 bits) and includes a serving cell ID 915 formed by 5 bits, a CORESET ID 920 formed by 4 bits, and a TCI status ID 925 formed by 7 bits.
Fig. 10 shows an example of a CORESET and search space beam configuration according to the description above. Referring to fig. 10, the base station may indicate one of the TCI status lists (indicated by reference numeral 1005) included in the CORESET 1000 configuration by MAC CE signaling. Thereafter, the UE considers the same QCL information (beam # 1) 1005 to be applied to one or more search spaces 1010, 1015, and 1020 connected to CORESET before indicating another TCI state to the corresponding CORESET through another MAC CE signaling. According to the PDCCH beam allocation method described above, it is difficult to indicate a beam change faster than a MAC CE signaling delay, and there is an advantage in that the same beam is immediately applied to each CORESET regardless of search space characteristics, and flexible PDCCH beam operation is difficult. Hereinafter, embodiments of the present disclosure provide more flexible PDCCH beam configuration and operation methods. In the following, in describing embodiments of the present disclosure, several different examples are provided for convenience of description, but these are not mutually exclusive and may be applied in combination with each other as appropriate.
The base station may provide the UE with a configuration of one or more TCI states of a particular set of control resources and may activate one of the configured TCI states by a MAC CE activation command. For example, { TCI state #0, TCI state #1, and TCI state #2} are configured as the TCI states in control resource set #1, and the base station may transmit an activate command to the UE through the MAC CE to assume TCI state #0 as the TCI state of control resource set # 1. Based on the activation command for the TCI state received by the MAC CE, the UE may correctly receive the DMRS of the corresponding control resource set based on the QCL information in the activated TCI state.
For the control resource set (control resource set # 0) with index configured to 0, if the UE does not receive the MAC CE activation command for the TCI state of control resource set #0, the UE may assume that the DMRS transmitted in control resource set #0 is quasi co-located with the SS/PBCH block identified during the initial access procedure or the non-contention-based access procedure that is not triggered by the PDCCH command.
Regarding a control resource set (control resource set #x) in which the index is configured to a value other than 0, if the UE has not received the TCI state of the control resource set #x or the UE is configured with one or more TCI states but has not received a MAC CE activation command for activating one of the TCI states, the UE may assume that the DMRS transmitted in the control resource set #x is quasi co-located with the SS/PBCH block identified during the initial access procedure.
[ PDSCH: frequency resource Allocation ]
Fig. 11 illustrates an example of frequency domain resource allocation of a Physical Downlink Shared Channel (PDSCH) in a wireless communication system according to an embodiment of the disclosure.
Fig. 11 shows three frequency domain resource allocation methods of type 0 (11-00), type 1 (11-05) and dynamic handover (11-10) that can be configured by a higher layer in an NR wireless communication system.
Referring to fig. 11, if a UE is configured to use only resource type 0 (indicated by reference numeral 11-00) via higher layer signaling, some Downlink Control Information (DCI) for allocating PDSCH to the corresponding UE includes a bitmap formed of NRBG bits. The conditions thereof will be described again later. In this case, NRBG represents the number of Resource Block Groups (RBGs) determined according to the BWP Size allocated by the BWP indicator and the higher layer parameters RBG-Size as shown in table 26 below, and data is transmitted to the RBG indicated as "1" in the bitmap.
TABLE 26
| Bandwidth portion size | Configuration 1 | Configuration 2 |
| 1-36 | 2 | 4 |
| 37-72 | 4 | 8 |
| 73-144 | 8 | 16 |
| 145-275 | 16 | 16 |
If the UE is configured via higher layer signaling to use only resource type 1 (indicated by reference numeral 11-05), some DCI for allocating PDSCH to the UE includesBit configured frequency domain resource allocation information. The conditions thereof will be described again later. With this information, the base station can configure the starting VRB 11-20 and the length 11-25 of the consecutively allocated frequency domain resources.
If the UE is configured to use both resource type 0 and resource type 1 (indicated by reference numeral 11-10) via higher layer signaling, some DCI for allocating PDSCH to the UE includes frequency domain resource allocation information configured by bits for configuring a larger value 11-35 between payloads 11-15 of resource type 0 and payloads 11-20 and 11-25 of resource type 1, the condition of which will be described later. Here, one bit is added to the Most Significant Bit (MSB) of the frequency domain resource allocation information in the DCI, 0 indicates the use of resource type 0 if the value of the corresponding bit is "0", and 1 indicates the use of resource type 1 if the value of the corresponding bit is "1".
[ PDSCH time Domain resource Allocation ]
Hereinafter, a method of allocating time domain resources for a data channel in a next generation mobile communication system (5G or NR system) will be described.
The base station may configure the UE with a table of time domain resource allocation information for a downlink data channel (physical downlink shared channel (PDSCH)) and an uplink data channel (physical uplink shared channel (PUSCH)) via higher layer signaling (e.g., RRC signaling). For PDSCH, a table including maxNrofDL-allocations= 16 entries may be configured, and for PUSCH, a table including maxNrofUL-allocations= 16 entries may be configured. In an embodiment, the time domain resource allocation information may include PDCCH-to-PDSCH slot timing (corresponding to a time interval in units of slots between a time point at which a PDCCH is received and a time point at which a PDSCH scheduled by the received PDCCH is transmitted, and denoted by K0), PDCCH-to-PUSCH slot timing (corresponding to a time interval in units of slots between a time point at which a PDCCH is received and a time point at which a PUSCH is scheduled by the received PDCCH is transmitted, and denoted by K2), information on a starting symbol position and length of a PDSCH or PUSCH scheduled within a slot, a mapping type of a PDSCH or PUSCH, and the like. For example, information such as table 27 or table 28 below may be transmitted from the base station to the UE.
TABLE 27
TABLE 28
The base station may notify the UE of one of the entries in the above table representing time domain resource allocation information via L1 signaling (e.g., DCI) (e.g., which may be indicated by a "time domain resource allocation" field in the DCI). The UE may obtain time domain resource allocation information for PDSCH or PUSCH based on DCI received from the base station.
Fig. 12 illustrates an example of time domain resource allocation of PDSCH in a wireless communication system according to an embodiment of the disclosure.
Referring to fig. 12, a base station may perform a base station according to subcarrier spacing (SCS) (μ) based on a data channel and a control channel configured using a higher layer PDSCH ，μ PDCCH ) The scheduling offset (K0) value and the starting position 12-00 and length 12-05 of the OFDM symbol in the slot dynamically indicated by the DCI to indicate the time domain position of the PDSCH resource.
Fig. 13 illustrates an example of time domain resource allocation according to subcarrier spacing of a data channel and a control channel in a wireless communication system according to an embodiment of the present disclosure.
Referring to fig. 13, if the data channel and the control channel have the same subcarrier spacing (13 a-00, μ PDSCH ＝μ PDCCH ) The base station and the UE may generate a scheduling offset adjusted according to the predetermined slot offset K0 since the number of data slots and the number of control slots are the same. On the other hand, the subcarrier spacing of the data channel and the subcarrier spacing of the control channel are different (13 a-05, μ PDSCH ≠ PDCCH ) In this case, since the number of data slots and the number of control slots are different, the base station and the UE may generate a scheduling offset adjusted according to the predetermined slot offset K0 based on the subcarrier spacing of the PDCCH.
[ UE capability report ]
In LTE and NR, a UE may perform a procedure of reporting capabilities supported by the UE to a corresponding base station when connected to a serving base station. In the following description, this is referred to as UE capability reporting.
The base station transmits a UE capability query message requesting a capability report to the UE in a connected state. The message may include a UE capability request for each Radio Access Technology (RAT) type of base station. The request for each RAT type may include supported band information, etc. In addition, the UE capability query message may issue a request for UE capability for one of the RAT types through one RRC message container transmitted by the base station, or the base station may transmit a UE capability query message including a UE capability request for each RAT type to the UE. That is, the UE capability query may be repeated a plurality of times, and the UE may configure a UE capability information message corresponding to the repeated UE capability query and make a plurality of reports of the UE capability information message. In the next generation telecommunication system, a UE capability request for multi-RAT dual connectivity (MR-DC) including NR, LTE and E-UTRA-NR dual connectivity (EN-DC) may be issued. In addition, in general, the UE capability query message is transmitted for the first time after the UE establishes a connection with the base station. However, if the base station requires, the UE capability query message may be requested under any condition.
In the above operation, the UE that receives the request for the UE capability report from the base station configures the UE capability according to the band information and RAT type requested by the base station. The method for configuring UE capabilities by a UE in an NR system can be summarized as follows:
1. if the UE receives a list of LTE and/or NR bands according to a UE capability request from the base station, the UE configures a Band Combination (BC) of EN-DC and NR independent (SA). That is, the UE configures the candidate BC list for EN-DC and NR SA based on the frequency band requested from the base station through FreqBandList. In addition, the bands are prioritized in the order described in FreqBandList.
2. If the base station requests the UE capability report by setting the "eutra-NR-only" flag or the "eutra" flag, the UE completely removes matters related to NR SA BC from the configured BC candidate list. This will only occur when an "eutra" capability is requested at the LTE base station (eNB).
3. Thereafter, the UE removes the back-off BC from the candidate BC list configured in the above operation. Here, the fallback BC refers to BC that may be obtained by removing a frequency band corresponding to at least one SCell frequency band from the random BC, and the fallback BC may be omitted since BC before removing the frequency band corresponding to the at least one SCell may already cover the fallback BC. This operation also applies to MR-DC, i.e., LTE band. The BC that remains after performing this operation is included in the final "candidate BC list".
4. The UE selects the BC to report by selecting the BC appropriate to the requested RAT type from the final "candidate BC list". In this operation, the UE configures the supplementadband communication list in a predetermined order. That is, the UE configures BC and UE capabilities to report according to a predetermined order of RAT types (nr→eutra-nr→eutra). In addition, the UE configures featureset combination for the configured supplementadband combination list and configures a list of "candidate feature set combinations" by a candidate BC list from which a list of fallback BC (including the same or lower level capabilities) has been removed. The above "candidate feature set combinations" include all feature set combinations of NR and EUTRA-NA BC, and may be obtained from the feature set combinations of UE-MRDC-Capabilities and UE-MRDC-Capabilities containers.
5. In addition, if the requested RAT type is EUTRA-NR and has some impact, the FeaturesCombinations are included in both UE-MRDC-Capabilities and UE-NR-Capabilities containers. However, the feature set of NR includes only UE-NR-Capabilities.
UE capabilities are configured and then the UE transmits a UE capability information message including the UE capabilities to the base station. Thereafter, the base station performs appropriate scheduling and transmission/reception management for the corresponding UE based on the UE capability received from the UE.
[CA/DC]
Fig. 14 illustrates a radio protocol structure of a base station and a UE in a single cell, carrier aggregation, and dual connectivity scenario in a wireless communication system according to an embodiment of the present disclosure.
Referring to fig. 14, radio protocols of the next generation mobile communication system include NR service data adaptation protocols (NR SDAPs) 1425 and 1470, NR packet data convergence protocols (NR PDCP) 1430 and 1465, and NR radio link control (NR RLC) 1435 and 1460, and NR medium access control (NR MAC) 1440 and 1455 for each of the UE and the NR base station.
The primary functions of NR spads 1425 and 1470 may include some of the following functions.
Transmission of user plane data
Mapping between QoS flows and data bearers (DRBs) of both DL and UL
Marking QoS flow IDs in both DL and UL packets
Reflective QoS flow to DRB mapping for UL SDAP PDU
Regarding the SDAP layer device, the UE may receive a configuration associated with whether to use a header of the SDAP layer device or whether to use a function of the SDAP layer device through an RRC message according to each PDCP layer device, each bearer, and each logical channel. If the SDAP header is configured, a one-bit NAS reflected QoS indicator (NAS reflected QoS) and a one-bit AS reflected QoS indicator (AS reflected QoS) of the SDAP header indicate that the UE updates or reconfigures mapping information between data bearers and QoS flows for the uplink and downlink. The SDAP header can include QoS flow ID information indicating QoS. The QoS information may be used as data processing priority, scheduling information, etc. for supporting the smooth service.
The primary functions of NR PDCP 1430 and 1465 may include some of the following functions.
Header compression and decompression: ROHC only
-transfer of user data
Sequential delivery of higher layer PDUs
Unordered delivery of higher layer PDUs
PDCP PDU reordering for reception
Duplicate detection of lower layer SDUs
Retransmission of PDCP SDUs
-encryption and decryption
Timer based SDU discard in uplink
In the above, the reordering function of the NR PDCP apparatus refers to a function of reordering PDCP PDUs received from a lower layer in order based on a PDCP Sequence Number (SN), and may include a function of transmitting data to a higher layer in the reordered order. Alternatively, the reordering function of the NR PDCP apparatus may include a function of transmitting data regardless of sequence, a function of reordering sequence and recording lost PDCP PDUs, a function of reporting status regarding lost PDCP PDUs to a transmitting end, and a function of requesting retransmission of lost PDCP PDUs.
The primary functions of NR RLC 1435 and 1460 may include some of the following functions:
delivery of higher layer PDUs
Sequential delivery of higher layer PDUs
Unordered delivery of higher layer PDUs
Error correction by ARQ
Concatenation, segmentation and reassembly of RLC SDUs
Re-segmentation of RLC data PDUs
Reordering of RLC data PDUs
-repeated detection
Protocol error detection
RLC SDU discard
RLC re-establishment
The sequential delivery function of the NR RLC device refers to a function of transmitting RLC SDUs received from a lower layer to a higher layer in the order of reception. The sequential delivery function of the NR RLC device may include: a function of reassembling and transmitting a plurality of RLC SDUs in case one RLC SDU is initially divided into a plurality of RLC SDUs and received; a function of reordering received RLC SDUs based on RLC Sequence Numbers (SNs) or PDCP SNs; a function of reordering the sequences and recording missing RLC PDUs; a function of reporting a status regarding the lost RLC PDU to a transmitting end; and a function of requesting retransmission of the missing RLC PDU. If missing RLC SDUs occur, the sequential delivery function of the NR RLC apparatus may include a function of sequentially transmitting RLC SDUs before the missing RLC SDUs only to a higher layer or sequentially transmitting all RLC SDUs received before a timer is started to a higher layer even if there is a missing RLC SDU in case of expiration of the timer. Alternatively, the sequential delivery function of the NR RLC device may include a function of sequentially transmitting all RLC SDUs currently received to a higher layer even if there are missing RLC SDUs if a timer expires. In addition, RLC PDUs may be processed in the order in which RLC PDUs is received (in order of arrival regardless of sequence number and sequence of sequence number), and may be transmitted to the PDCP device in an out-of-order delivery manner. In the case of segmentation, the in-sequence delivery function may include a function of receiving the segments stored in the buffer or segments to be received later, reconfiguring the segments in one complete RLC PDU, processing the RLC PDU, and transmitting the RLC PDU to the PDCP device. The NR RLC layer may not include a concatenation function, and the concatenation function may be performed by the NR MAC layer or may be replaced by a multiplexing function of the NR MAC layer.
In the above, the out-of-order delivery function of the NR RLC apparatus refers to a function of transmitting RLC SDUs received from a lower layer directly to a higher layer regardless of order, and if one RLC SDU is initially segmented into a plurality of RLC SDUs and received, a function of reassembling the plurality of RLC SDUs and transmitting, and a function of storing RLC SN or PDCP SN of received RLC PDUs, reordering sequences, and recording lost RLC PDUs may be included.
NR MACs 1440 and 1455 may be connected to a plurality of NR RLC layer apparatuses configured in one UE, and main functions of the NR MACs may include some of the following functions:
mapping between logical channels and transport channels
Multiplexing/de-multiplexing of MAC SDUs
Scheduling information reporting
Error correction by HARQ
Priority handling between logical channels of a UE
Priority handling between UEs by means of dynamic scheduling
MBMS service identification
Transport format selection
-filling
NR PHY layers 1445 and 1450 may perform the following operations: channel coding and modulating higher layer data, generating higher layer data into OFDM symbols, transmitting OFDM symbols via a radio channel, or demodulating and channel decoding OFDM symbols received via a radio channel, and transmitting OFDM symbols to higher layers.
The detailed structure of the radio protocol structure may be variously changed according to a carrier (or cell) operation method. For example, when the base station performs single carrier (or cell) based data transmission to the UE, the base station and the UE use a protocol structure having a single structure for each layer, such as 1400. On the other hand, when the base station transmits data to the UE based on Carrier Aggregation (CA) using a plurality of carriers in a single TRP, the base station and the UE up to RLC have a single structure, but use a protocol structure such as 1410 that multiplexes the PHY layer through the MAC layer. As another example, when the base station transmits data to the UE based on Dual Connectivity (DC) using a plurality of carriers among a plurality of TRPs, the base station and the terminal up to the RLC have a single structure, but use a protocol structure in which PHY layers are multiplexed through a MAC layer, such as 1420.
[NC-JT]
According to embodiments of the present disclosure, non-coherent joint transmission (NC-JT) may be used for a UE to receive PDSCH from multiple TRPs.
Unlike the conventional communication system, the 5G wireless communication system can support not only a service requiring a high transmission rate but also a service having an extremely short transmission delay and a service requiring a high connection density. In a wireless communication network including a plurality of cells, transmission-reception points (TRPs), or beams, cooperative transmission between the respective cells, TRPs, and/or beams may satisfy various service requirements by increasing signal strength received by a UE or efficiently performing interference control between the respective cells, TRPs, or/and beams.
Joint Transmission (JT) is one representative transmission technique of the above cooperative communication, which performs signal transmission to one UE through a plurality of different cells, TRPs, and/or beams to increase throughput or signal strength received by the UE. Here, the channels between the respective cells, TRPs, and/or beams and the UE may have significantly different characteristics. In particular, non-coherent joint transmission (NC-JT) supporting non-coherent precoding (separate precoding) between cells, TRPs and/or beams may require separate precoding, MCS, resource allocation, TCI indication, etc. depending on the link-specific channel characteristics between each cell, TRP and/or beam and the UE.
The NC-JT transmission described above may be applied to at least one of a downlink data channel (physical downlink shared channel (PDSCH)), a downlink control channel (physical downlink control channel (PDCCH)), an uplink data channel (physical uplink shared channel (PUSCH)), and an uplink control channel (physical uplink control channel (PUCCH)). During PDSCH transmission, transmission information such as precoding, MCS, resource allocation, and TCI is indicated by DL DCI, and in order to perform NC-JT transmission, transmission information needs to be indicated independently for each cell, TRP, and/or beam. This is a major factor that increases the payload required for DL DCI transmission, which may adversely affect the reception performance of the PDCCH for DCI transmission. Therefore, for JT support of PDSCH, it is necessary to carefully design a trade-off between DCI information amount and control information reception performance.
Fig. 15 illustrates an example of an antenna port configuration and resource allocation for PDSCH transmission using cooperative communication in a wireless communication system according to an embodiment of the present disclosure.
Referring to fig. 15, an example for PDSCH transmission according to a Joint Transmission (JT) scheme is shown, and an example of radio resource allocation to each TRP is shown.
In fig. 15, an example of coherent joint transmission (C-JT) supporting phase-interference coding between cells, TRPs, and/or beams is shown (indicated by reference numeral 1500).
In the case of C-JT, TRP a 1505 and TRP B1510 may transmit a single data (PDSCH) to UE 1515, and multiple TRPs may perform joint precoding. This may refer to the same PDSCH transmission using the same DMRS port in TRP a 1505 and TRP B1510. For example, TRP a 1505 and TRP B1510 may transmit DRMS to the UE through DMRS port a and DMRS B, respectively. In this case, the UE may receive one DCI information for receiving one PDSCH demodulated based on DMRS transmitted through DMRS ports a and B.
In fig. 15, an example of incoherent joint transmission (NC-JT) supporting incoherent precoding between individual cells, TRPs and/or beams is shown (indicated by reference numeral 1520).
In the case of NC-JT, PDSCH is transmitted to the UE 1535 for each cell, TRP, or/and beam, and separate precoding may be applied to each PDSCH. Each cell, TRP, and/or beam may be used to transmit a different PDSCH or different PDSCH layer to the UE to improve throughput compared to single cell, TRP, and/or beam transmissions. In addition, each cell, TRP, and/or beam may repeatedly transmit the same PDSCH to the UE to improve reliability compared to single cell, TRP, and/or beam transmissions. For ease of explanation, cells, TRPs and/or beams are hereinafter collectively referred to as TRPs.
Here, when frequency and time resources used for PDSCH transmission by the plurality of TRPs are the same (indicated by reference numeral 1540), when frequency and time resources used by the plurality of TRPs are not overlapped at all (indicated by reference numeral 1545), and when certain frequency and time resources used by the plurality of TRPs are overlapped (indicated by reference numeral 1550), various radio resource allocations may be considered.
In order to simultaneously allocate a plurality of PDSCH to one UE to support NC-JT, DCI of various types, structures, and relationships may be considered.
Fig. 16 illustrates an example configuration of Downlink Control Information (DCI) for NC-JT for transmitting a different PDSCH or a different PDSCH layer to a UE through each TRP in a wireless communication system according to an embodiment of the present disclosure.
Referring to fig. 16, case #1 (1600) shows the following example: in case of transmitting (N-1) different PDSCHs from (N-1) additional TRPs (TRP #1 to trp# (N-1)) other than the service TRP (TRP # 0) for single PDSCH transmission, control information for PDSCH transmitted from (N-1) additional TRPs and control information for PDSCH transmitted in the service TRP are transmitted independently from each other. That is, the UE may obtain control information for PDSCH transmitted from different TRPs (TRP #0 to trp# (N-1)) through independent DCIs (DCI #0 to dci# (N-1)). The formats between the independent DCIs may be the same or different from each other, and the payloads between the DCIs may be the same or different from each other. In case #1 described above, the degree of freedom of control or allocation for each PDSCH may be fully ensured, but when each DCI is transmitted from different TRPs, a difference in coverage of each DCI may occur and reception performance may be degraded.
Case #2 (1605) shows the following example: in case of transmitting (N-1) different PDSCHs from (N-1) additional TRPs (TRP #1 to trp# (N-1)) other than the service TRP (TRP # 0) for single PDSCH transmission, wherein each control information (DCI) of the PDSCH transmitted from (N-1) additional TRPs is transmitted and each DCI depends on the control information for PDSCH transmitted from the service TRP.
For example, in the case of dci#0 as control information for PDSCH transmitted from service TRP (trp#0), all information elements in DCI format 1_0, DCI format 1_1, and DCI format 1_2 are included, but short DCI (hereinafter, sdi) (sdi#0 to sdi# (N-2)) as control information for PDSCH transmitted from cooperative TRP (trp#1 to trp# (N-1)) may include only some information elements in DCI format 1_0, DCI format 1_1, and DCI format 1_2. Accordingly, in the case of a sci for control information transmission for PDSCH transmitted from cooperative TRP, a payload for transmitting control information related to PDSCH transmitted from serving TRP may be smaller than normal DCI (nci), and thus may include reserved bits as compared to nci.
In case #2 described above, the degree of freedom in controlling or allocating each PDSCH may be limited according to the content of the information element included in the sdi, or since the receiving performance of the sdi is better than that of the nci, the probability of coverage difference per DCI may be reduced.
Case #3 (1610) shows the following example: in case of transmitting (N-1) different PDSCHs from (N-1) additional TRPs (TRP #1 to TRP # (N-1)) other than the service TRP (TRP # 0) used when transmitting a single PDSCH, one control information for PDSCH of (N-1) additional TRPs is transmitted and the DCI depends on the control information for PDSCH transmitted from the service TRP.
For example, in the case of dci#0 being control information for PDSCH transmitted from service TRP (trp#0), all information elements in DCI format 1_0, DCI format 1_1, and DCI format 1_2 are included, and in the case of control information for PDSCH transmitted from cooperative TRP (trp#1 to trp# (N-1)), only some of the information elements in DCI format 1_0, DCI format 1_1, and DCI format 1_2 may be included in one "secondary" DCI (sdi) and transmitted. For example, the sdi may include at least one of HARQ related information, such as frequency domain resource allocation, time domain resource allocation, and MCS of cooperative TRP. In addition, in the case where information such as a bandwidth part (BWP) indicator or a carrier indicator is not included in the sdi, DCI (dci#0, normal DCI, ncui) serving TRP may be followed.
In case #3 (1610), the degree of freedom of control or allocation for each PDSCH may be limited according to the content of the information element included in the sdi. However, the reception performance of the sci may be adjusted, and the complexity of DCI blind decoding of the UE may be reduced compared to case #1 (1600) or case #2 (1605).
Case #4 (1615) shows the following example: in case of transmitting (N-1) different PDSCHs from (N-1) additional TRPs (TRP #1 to trp# (N-1)) other than the service TRP (TRP # 0) for single PDSCH transmission, control information for PDSCH transmitted from (N-1) additional TRPs is transmitted through the same DCI (long DCI (LDCI)) as control information for PDSCH transmitted from the service TRP. That is, the UE may obtain control information for PDSCH transmitted from different TRPs (TRP #0 to trp# (N-1)) through a single DCI. In case #4 (1615), the complexity of DCI blind decoding of the UE may not be increased, but the degree of freedom in controlling or allocating PDSCH may be low, so that the number of cooperative TRPs is limited according to a long DCI payload limit.
In the following description and embodiments, scdci may refer to various supplementary DCIs including PDSCH control information transmitted in cooperative TRP, such as shortened DCI, auxiliary DCI, or normal DCI (PDI formats 1_0 to 1_1 described above). If not specified, the above description applies similarly to each piece of supplemental DCI.
In the following description and embodiments, at least one DCI (PDCCH) may be used for NC-JT supported cases #1 (1600), #2 (1605), and #3 (1610) may be classified into NC-JT based on a plurality of PDCCHs, and a single DCI (PDCCH) may be used for NC-JT supported cases #4 (1615) may be classified into NC-JT based on a single PDCCH. In PDSCH transmission based on multiple PDCCHs, CORESET of DCI scheduling a service TRP (trp#0) may be distinguished from CORESET of DCI scheduling cooperation TRP (trp#1 to trp# (N-1)). As a method of distinguishing CORESET, there may be a method of distinguishing by a higher level indicator of each CORESET, a method of distinguishing by a beam configuration of each CORESET, or the like. In addition, in NC-JT based on a single PDCCH, a single DCI schedules a single PDSCH having a plurality of layers instead of scheduling a plurality of PDSCHs, and the plurality of layers may be transmitted from a plurality of TRPs. Here, the connection relationship between a layer and a TRP for transmitting the layer may be indicated by a Transmission Configuration Indicator (TCI) indication indicating the layer.
In embodiments of the present disclosure, when actually used, the "cooperative TRP" may be replaced with various terms including "cooperative panel" or "cooperative beam".
In the embodiments of the present disclosure, for convenience of explanation, the expression "apply NC-JT" is used herein, but may be interpreted differently depending on the context, such as "UE receives one or more PDSCH simultaneously in one BWP", "UE receives PDSCH simultaneously in one BWP based on two or more Transmission Configuration Indicator (TCI) indications in one BWP", "PDSCH received by UE is associated with one or more DMRS port groups", and so on.
In the present disclosure, the radio protocol architecture for NC-JT may be used differently according to TRP development scenarios. For example, when there is no backhaul delay or backhaul delay is small between cooperative TRPs, a MAC layer multiplexing-based structure similar to S10 (CA class method) of fig. 11 may be used. On the other hand, when the backhaul delay between cooperative TRPs is so large that the backhaul delay cannot be ignored (for example, when information exchange such as CSI, scheduling, HARQ-ACK, etc. between cooperative TRPs requires 2ms or more), a robust delay feature can be ensured by using an independent structure (DC-like method) for each TRP from the RLC layer, similarly to S20 of fig. 11.
The UE supporting C-JT/NC-JT may receive C-JT/NC-JT related parameters or set values from a higher layer configuration, and may set RRC parameters of the UE based on the received parameters or values. For higher layer configurations, the UE may utilize UE capability parameters, e.g., tci-StatePDSCH. Here, the UE capability parameter (e.g., TCI-StatePDSCH) may define TCI states for PDSCH transmission purposes, and the number of TCI states may be configured to 4, 8, 16, 32, 64, and 128 in FR1, 64 and 128 in FR2, and up to eight states in the configured number, which may be indicated by the 3 bits of the TCI field in the DCI through a MAC CE message. The maximum value 128 represents a value indicated by maxnumberconfiguredtstatstatepercc included in tci-StatePDSCH parameters in the capability signaling of the UE. Accordingly, a series of configuration procedures from a higher layer configuration to a MAC CE configuration may be applied to a beamforming indication or a beamforming change command of at least one PDSCH in one TRP.
[ multiple TRP based on multiple DCIs ]
According to embodiments of the present disclosure, a downlink control channel for NC-JT transmission may be configured based on multiple PDCCHs.
In NC-JT based on multiple PDCCHs, there may be a CORESET or search space that is not differentiated for each TRP when DCI transmission is performed for PDSCH scheduling of each TRP. The CORESET or search space of each TRP may be configured to be at least one of the following.
Higher level index configuration of CORESET: the CORESET configuration information configured as a higher layer may include an index value, and TRP for transmitting the PDCCH in the corresponding CORESET may be distinguished by the index value of CORESET for each configuration. That is, in the CORESET set having the same higher layer index value, it can be considered that the same TRP transmits PDCCH or PDCCH for scheduling PDSCH in the same TRP is transmitted. The above index of each CORESET may be referred to as coresetpoolndex, and for CORESETs configured with the same coresetpoolndex value, the PDCCH may be considered to be transmitted from the same TRP. In the case where CORESET is not configured with coresetpoolndex value, the default value of coresetpoolndex may be considered to have been configured, and may be 0.
Multiple PDCCH-Config configuration: a plurality of PDCCH-configs are configured in one BWP, and each PDCCH-Config may include a PDCCH configuration for each TRP. That is, one PDCCH-Config may include a TRP-specific CORESET list and/or a search space list of TRPs, and one or more CORESETs and one or more search spaces included in the PDCCH-Config may be considered to correspond to the specific TRPs.
CORESET beam/beam group configuration: the TRP corresponding to a respective CORESET may be distinguished by the beam or beam group configured for each CORESET. For example, when the same TCI state is configured in a plurality of CORESETs, the corresponding CORESETs may be considered to be transmitted through the same TRP, or PDCCHs for scheduling PDSCH in the same TRP may be considered to be transmitted in the corresponding CORESETs.
Search space beam/beam group configuration: beams or beam groups are configured for each search space, and by doing so, TRPs for each search space can be distinguished. For example, when the same beam/beam group or TCI state is configured in a plurality of search spaces, it may be considered that PDCCHs are transmitted in the search spaces with the same TRP or PDCCHs for scheduling PDSCH in the same TRP are transmitted in the search spaces.
By dividing the CORESET or search space of each TRP as described above, PDSCH and HARQ-ACK information of each TRP can be classified, and thus, an independent HARQ-ACK codebook for each TRP can be generated and independent PUCCH resources can be used.
The above configuration may be independent for each cell or for each BWP. For example, where two different coresetpoolndex values are configured in a PCell, coresetpoolndex values may not be configured in a particular SCell. Here, it can be considered that NC-JT transmission is configured in the PCell, and NC-JT transmission is not configured in scells not configured with coreetpolindx values.
[ Single DCI-based multiple TRP ]
According to another embodiment of the present disclosure, a downlink beam for NC-JT transmission may be configured based on a single PDCCH.
In NC-JT based on a single PDCCH, PDSCH transmitted by multiple TRPs may be scheduled by one DCI. Here, the number of TCI states may be used as a method of indicating the number of TRPs for transmitting the corresponding PDSCH. That is, if the number of TCI states indicated in DCI for scheduling PDSCH is 2, NC-JT transmission based on a single PDCCH may be considered, and if the number of TCI states is 1, single TRP transmission may be considered. The TCI state indicated by the DCI may correspond to one or both of the TCI states activated by the MAC-CE. When the TCI state of the DCI corresponds to two TCI states activated by the MAC-CE, a correspondence is established between the TCI code point indicated by the DCI and the TCI state activated by the MAC-CE, and there may be two TCI states activated by the MAC-CE corresponding to the TCI code point.
The above configuration may be independent for each cell or for each BWP. For example, a PCell may have at most two activated TCI states corresponding to one TCI code point, while a particular SCell may have at most one activated TCI state corresponding to one TCI code point. Here, it can be considered that NC-JT transmission is configured in the PCell, whereas NC-JT transmission is not configured in the above SCell.
Meanwhile, referring to the description related to the above PDCCH and beam configuration, since PDCCH repetition transmission is not supported in the general method, it is difficult to achieve desired reliability in a scene where high reliability is required, such as URLLC. Accordingly, the present disclosure proposes a method for improving PDCCH reception reliability by providing a PDCCH repetition transmission method through a plurality of transmission points (TRPs).
Hereinafter, for convenience of explanation in the present disclosure, cells, transmission points, panels, beams, and/or transmission directions, which can be distinguished by higher layer/L1 parameters such as TCI status or spatial relationship information, or indicators such as cell IDs, TRP IDs, panel IDs, etc., are collectively described as Transmission Reception Points (TRPs). Accordingly, in practical applications, TRP may be appropriately replaced with one of the above terms.
Hereinafter, in the present disclosure, when a UE determines whether to apply cooperative communication, the UE may use various methods such as: the PDCCH allocated to the PDSCH to which the cooperative communication is applied has a specific format, and includes a specific indicator indicating whether the cooperative communication is applied or not, the PDCCH allocated to the PDSCH to which the cooperative communication is applied is scrambled by a specific RNTI, or it is assumed that the cooperative communication is applied in a specific interval indicated by a higher layer. Hereinafter, for convenience of description, a case in which the UE receives the PDSCH to which cooperative communication is applied based on the similar conditions as described above will be referred to as an NC-JT case.
On the other hand, the base station according to the embodiments of the present disclosure is a subject to perform resource allocation for the UE, and may be at least one of a gNode B, a gNB, an eNode B, a node B, a Base Station (BS), a radio access unit, a base station controller, or a network node. The UE 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 communication functions. Hereinafter, embodiments of the present disclosure will be described using a 5G system as an example, but may be applied to other communication systems having similar technical backgrounds or channel types. For example, LTE or LTE-a mobile communication and mobile communication technologies developed after 5G may be included therein. Accordingly, embodiments of the present disclosure may be applied to other communication systems by making some modifications within the scope not significantly departing from the scope of the present disclosure as determined by one of ordinary skill in the art. The present disclosure applies to FDD and TDD systems.
In addition, in the description of the present disclosure, if it is determined that detailed descriptions of related functions or configurations may unnecessarily obscure the subject matter of the present disclosure, the detailed descriptions thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present disclosure, which may vary according to intention or convention of a user or operator. Therefore, it should be defined based on the content of the entire specification.
The present disclosure applies to FDD and TDD systems. Hereinafter, in describing the present disclosure, higher layer signaling (or higher layer signaling) is a signal transmission method of transmitting a signal from a base station to a UE using a downlink data channel of a physical layer or transmitting a signal from a UE to a base station using an uplink data channel of a physical layer, and may be referred to as RRC signaling, PDCP signaling, or a Medium Access Control (MAC) control element (MAC CE). In particular, the higher layer signaling may be signaling corresponding to at least one or a combination of one or more of the following signaling.
-Master Information Block (MIB)
-System Information Block (SIB) or SIB X (x=1, 2, … …)
-Radio Resource Control (RRC)
-a Medium Access Control (MAC) Control Element (CE)
In addition, L1 signaling may be a signal corresponding to at least one of the following physical layer channels or signaling methods or a combination of one or more of them.
-Physical Downlink Control Channel (PDCCH)
Downlink Control Information (DCI)
UE-specific DCI
-group common DCI
-common DCI
Scheduling DCI (e.g., DCI for scheduling downlink or uplink data)
Non-scheduling DCI (e.g., DCI not used for the purpose of scheduling downlink or uplink data)
-Physical Uplink Control Channel (PUCCH)
Uplink Control Information (UCI)
Meanwhile, in the present disclosure, transmitting or receiving a PDCCH may be understood as performing transmission or reception of DCI through the PDCCH.
In addition, in the present disclosure, transmitting or receiving PDSCH may be understood as performing transmission or reception of data through PDSCH.
In addition, in the present disclosure, transmitting or receiving PUSCH may be understood as performing transmission or reception of data through PUSCH.
Hereinafter, in the present disclosure, determining the priority between a and B means selecting one of higher priorities and performing an operation corresponding thereto according to a predetermined priority rule, or omitting or discarding an operation corresponding to one of lower priorities.
Hereinafter, in the present disclosure, the above embodiments will be described by a plurality of embodiments, but the embodiments are not independent, and one or more embodiments may be applied simultaneously or in combination.
< first embodiment: PDCCH repeated transmitting method based on multiple TRPs
As an embodiment of the present disclosure, a PDCCH repetition transmission method based on multiple TRPs will be described. The multi-TRP-based PDCCH repetition transmission method may include various methods according to the application of each TCI state, each TCI state to be applied when PDCCH transmission occurs in each TRP being applied to the above-described various parameters for PDCCH transmission. For example, various parameters that apply different TCI states for PDCCH transmission may include CCEs, sets of PDCCH candidates, sets of control resources, search spaces, and so on. In the case of the multi-TRP-based PDCCH repetition transmission method, a soft combining method, a selection method, and the like may be regarded as a reception method of the UE.
The PDCCH repetition transmission through the multi-TRP may include at least the following five methods, and the base station may configure at least one of the five methods for the UE through higher layer signaling, may indicate the method through L1 signaling, or may configure or indicate the method through a combination of higher layer signaling and L1 signaling. Meanwhile, the following methods are provided as examples, and the present disclosure is not limited thereto. That is, PDCCH repetition transmission according to the present disclosure may be performed based on a method obtained by combining the following methods.
Method 1-1 method of repeatedly transmitting multiple PDCCHs having the same payload
One method 1-1 is a method of repeatedly transmitting a plurality of control information having the same DCI format and payload. In each of the above control information, information for scheduling a repeatedly transmitted PDSCH (e.g., { pdsch#1, pdsch#2, … …, pdsch#y } repeatedly transmitted over a plurality of slots) may be indicated. The fact that each control information repeatedly transmitted has the same payload can be expressed as, for example, the number of times PDSCH is repeatedly transmitted, PDSCH allocation information in the time domain (e.g., the number of PDSCH symbols and slot offset (k_0) between control information and pdsch#1), PDSCH resource allocation information in the frequency domain, DMRS port allocation information, PDSCH scheduling information for each control information of PDSCH to HARQ-ACK timing, PUCCH resource indicator, etc., which is the same for each control information. The UE may improve the reception reliability of the control information by soft combining the repeated transmission control information having the same payload.
For the above soft combining, the UE needs to know the resource location of the control information to be repeatedly transmitted, the number of repeated transmissions, and the like in advance. To this end, the base station may instruct in advance at least one of the time domain, frequency domain, and spatial domain resource configurations of the above-described repeated transmission control information.
When the control information is repeatedly transmitted in the time domain, the control information may be repeatedly transmitted on different CORESETs, on different sets of search spaces in one CORESET, or may be repeatedly transmitted on different PDCCH monitoring occasions in one CORESET and one set of search spaces. The resource units (core unit, search space set unit, PDCCH monitoring occasion unit) repeatedly transmitted in the time domain and the positions of the repeatedly transmitted resources (PDCCH index candidates, etc.) may be indicated by a higher layer configuration of the base station, etc. Here, the number of repeated transmissions of the PDCCH and/or a list of TRPs participating in the repeated transmission and a transmission mode may be explicitly indicated, and a higher layer indication, MAC-CE/L1 signaling, etc. may be used as an explicit indication method. Here, the list of TRP may be indicated in the form of the TCI state or QCL hypothesis described above.
When the control information is repeatedly transmitted in the frequency domain, the control information may be repeatedly transmitted on different CORESETs, on different PDCCH candidates in one CORESET, or for each CCE. The units of the resources to be repeatedly transmitted in the frequency domain and the positions of the repeated transmission resources may be indicated by a higher layer configuration of the base station or the like. In addition, the number of repeated transmissions and/or the list of TRPs and transmission patterns participating in the repeated transmissions may be explicitly indicated, and higher layer indication or MAC-CE/L1 signaling may be used as an explicit indication method. Here, the list of TRP may be indicated in the form of the TCI state or QCL hypothesis described above.
When the control information is repeatedly transmitted in the spatial domain, the control information may be repeatedly transmitted on different CORESETs, or two or more TCI states may be configured in one CORESET, and thus, the repeated transmission may be performed.
Method 1-2 method of repeatedly transmitting a plurality of control information which may have different DCI formats and/or payloads
One method 1-2 is a method of repeatedly transmitting a plurality of control information which may have different DCI formats and/or payloads. The control information schedules repeated transmission of PDSCH, and the number of PDSCH repetition indicated by each control information may be different from each other. For example, pdcch#1 may indicate information for scheduling { pdsch#1, pdsch#2, … …, pdsch#y }, while pdcch#2 indicates information for scheduling { pdsch#2, … …, pdsch#y }, … …, and pdcch#x may indicate information for scheduling { PDSCH Y }. The control information repeated transmission method has an advantage in that the total delay time required for repeated transmission of the control information and PDSCH can be reduced as compared with the method 1-1.
In the above-described method 1-2, the UE may not need to know the resource location and the number of repeated transmissions of the control information to be repeatedly transmitted in advance, and the UE may independently decode and process each of the repeated transmitted control information. If the UE decodes a plurality of repeated transmission control information for scheduling the same PDSCH, only the first repeated transmission control information may be processed and the second and subsequent repeated transmission control information may be ignored. Alternatively, the resource position and the number of repeated transmissions of the control information to be repeatedly transmitted may be indicated in advance, and the indication method may be the same as that described in method 1-1.
Methods 1-3 methods of repeatedly transmitting a plurality of control information, wherein each control information may have a different DCI format and/or payload
A method 1-3 is a method for repeatedly transmitting a plurality of control information, wherein each control information may have a different DCI format and/or payload. Here, each control information repeatedly transmitted may have the same DCI format and the same payload. Method 1-3 is a method that takes advantage of the advantages of methods 1-1 and 1-2, and according to method 1-3, control information can be transmitted with high reliability compared to method 1-2 while reducing the total delay time required for repeatedly transmitting control information and PDSCH compared to method 1-1.
In method 1-3, soft combining of method 1-1 and separate decoding of method 1-2 may be used to decode and soft combine the repeatedly transmitted control information. For example, first transmission control information among repeated transmissions of a plurality of control information, each of which may have a different DCI format and/or payload, may be decoded according to method 1-2, and soft combining may be performed on the repeated transmissions of the decoded control information according to method 1-1 described above.
Meanwhile, the base station may select and configure one of methods 1-1, 1-2, or 1-3 to perform repeated transmission of control information. The control information repeated transmission method may be explicitly indicated to the UE by the base station through higher layer signaling. Alternatively, the control information repeated transmission method may be indicated in combination with other configuration information. For example, a higher layer configuration indicating a PDSCH repeated transmission method may be combined with an indication for control information repeated transmission. When it is instructed to repeatedly transmit PDSCH using a Frequency Division Multiplexing (FDM) method, it can be understood that control information is repeatedly transmitted using only method 1-1. The reason is that the PDSCH repeated transmission according to the FDM scheme, methods 1-2 have no effect of reducing the delay time. For similar reasons, when it is instructed to repeatedly transmit PDSCH using an intra-slot Time Division Multiplexing (TDM) method, it can be understood that control information is repeatedly transmitted using method 1-1. On the other hand, when it is instructed to repeatedly transmit PDSCH using the inter-slot TDM scheme, the above-described method 1-1, method 1-2, or method 1-3 for control information repetition transmission may be selected through higher layer signaling or L1 signaling.
On the other hand, the base station may explicitly indicate the unit of control information repeated transmission to the UE through a higher layer configuration or the like. Alternatively, the unit of repeated transmission of control information may be indicated in combination with other configuration information. For example, a higher layer configuration indicating a PDSCH repeated transmission method may be combined with a unit of control information repeated transmission. When the FDM scheme is instructed to repeatedly transmit PDSCH, it may be interpreted as repeatedly transmitting control information through FDM or Space Division Multiplexing (SDM). The reason is that if the control information is repeatedly transmitted, such as through an inter-slot TDM scheme, there is no effect of reducing delay time due to the repeated transmission of PDSCH using the FDM scheme. For similar reasons, when it is instructed to repeatedly transmit PDSCH using an intra-slot TDM scheme, it may be interpreted as repeatedly transmitting control information in a slot by TDM, FDM, or SDM. On the other hand, when it is instructed to repeatedly transmit PDSCH using the inter-slot TDM scheme, inter-slot TDM, intra-slot TDM, FDM, or SDM may be selected by higher layer signaling or the like to repeatedly transmit control information.
Methods 1-4 PDCCH transmission method in which corresponding TCI states are applied to different CCEs in the same PDCCH candidate
According to one method 1-4, in order to improve the reception performance of a PDCCH without repeatedly transmitting the PDCCH, different TCI states related to from among multi-TRP transmission can be applied to different CCEs in a PDCCH candidate and transmitted. Although this method is not PDCCH repetition transmission, different CCEs in the PDCCH candidates are transmitted by applying different TCI states in each TRP, and thus it may be a method of obtaining spatial diversity of the PDCCH candidates. The different CCEs to which the different TCI states are applied may be separated in the time or frequency dimension, and the UE needs to know the location of the resources to which the different TCI states are applied in advance. The UE may receive different CCEs in the same PDCCH candidate to which different TCI states are applied and decode the received CCEs independently or simultaneously. Here, in order to apply the corresponding TCI state to different CCEs in a specific PDCCH candidate, one or more TCI states are configured in a control resource set where the corresponding PDCCH candidate may exist, or may be activated through MAC-CE.
Methods 1-5 PDCCH transmitting methods (SFN methods) in which a plurality of TCI states are applied to all CCEs in the same candidate PDCCH
According to one method 1-5, in order to improve the reception performance of a PDCCH without repeatedly transmitting the PDCCH, a plurality of TCI states may be applied to different CCEs in a PDCCH candidate and transmitted. Although this method is not PDCCH repetition transmission, it may be a method of obtaining spatial diversity by SFN transmission at the same CCE location in the PDCCH candidate set. The UE may receive CCEs of the same location in the same PDCCH candidate set to which different TCI states are applied, and may decode the received CCEs using some or all of the plurality of TCI states independently or simultaneously. Here, in order to apply a plurality of TCI states to all CCEs in the same PDCCH candidate, one or more TCI states are configured in a control resource set where a corresponding PDCCH candidate may exist, or may be activated through MAC-CE.
In addition, in order to perform multi-TRP-based PDCCH repetition transmission, some configurations or operations between the above-described methods may be selectively combined/combined and applied.
< second embodiment: UE capability reporting related to soft combining during PDCCH repeated transmission >
The UE may report to the base station UE capability reports related to soft combining during PDCCH repetition transmissions, and several methods may exist in this regard. The following specific methods may exist.
UE capability reporting method 1 the UE may report to the base station UE capability related only to whether soft combining is possible during PDCCH repetition transmission in a possible or impossible form.
As an example, if the UE reports information indicating that soft combining is possible during PDCCH repetition transmission as UE capability to the base station, the base station may most flexibly determine whether soft combining is possible for the UE (e.g., the UE determines that soft combining is possible on a Log Likelihood Ratio (LLR) level) and may notify the UE of the configuration related to PDCCH repetition transmission as flexibly as possible during PDCCH transmission related configuration. Here, as an example related to PDCCH repetition configuration, for a UE, a base station assumes that soft combining between control resource sets or search spaces having different configurations, soft combining between candidate PDCCHs having the same aggregation level, or soft combining between candidate PDCCHs having different aggregation levels is possible, and may notify the UE of the corresponding configuration.
As another example, if the UE reports information indicating that soft combining is possible during PDCCH repetition transmission as UE capability to the base station, the base station may most conservatively determine a level at which soft combining is possible for the UE (e.g., determine that soft combining is possible for the UE on an OFDM symbol level), and may notify the UE of the configuration related to PDCCH repetition transmission in a most restrictive manner during PDCCH transmission related configuration. Here, as an example related to PDCCH repetition configuration, the base station may assume that soft combining between a plurality of control resource sets having the same configuration or soft combining between candidate PDCCHs having the same aggregation level is possible for the UE, and may notify the UE of the corresponding configuration.
The UE capability reporting method 2 in order to represent a possible soft combining operation in the UE as the UE capability in more detail, the UE may divide the soft combining possibility during the PDCCH repetition transmission into levels and report the same level as the UE capability to the base station, as compared to the above-described UE capability reporting method 1. For example, the UE may identify a signal level at which soft combining may be applied for PDCCH repetition transmission from among signal levels generated through a UE reception operation procedure, and may report such information as UE capability to the base station. For example, the UE may notify that soft combining is possible on an OFDM symbol level, which is a signal level where soft combining may be applied, may notify that soft combining is possible on a modulation symbol level, and may notify that soft combining is possible on an LLR level. Based on each signal level reported by the UE, the base station may provide a notification of the appropriate configuration so that the UE may perform soft combining based on the reported UE capabilities.
[ UE capability reporting method 3] the UE can report to the base station the restrictions required to enable soft combining at the UE end during PDCCH repeated transmission as UE capability. As an example, the UE may report to the base station that the configuration of each of the control resource sets including the two duplicate PDCCHs should be the same. As another example, the UE may report to the base station that two duplicate PDCCH candidates need to have at least the same aggregation level.
[ UE capability reporting method 4] when PDCCH retransmission is received from a base station, a UE can report information related to a supported PDCCH retransmission method through UE capability. As an example, the UE may report information about supporting methods 1-5 (SFN transmission methods) to the base station. As another example, the UE may report information about intra-slot TDM, inter-slot TDM, or FDM schemes in supporting method 1-1 (a method of repeatedly transmitting a plurality of PDCCHs having the same payload) to the base station. In particular, in the case of TDM, the UE may report the maximum value of the time interval between two duplicate PDCCHs to the base station. As an example, if the UE reports that the maximum value of the time interval between two repeated PDCCHs is 4 OFDM symbols, the base station should adjust the time interval between two repeated PDCCHs to 4 OFDM symbols or less when performing TDM-based PDCCH repeated transmission to the UE according to the corresponding information.
In practical applications, the above-described UE capability reporting method may be configured as a combination of two or more UE capability reporting methods. As an example, it is possible that the UE may report soft combining at the LLR level through [ UE capability reporting method 2], while the UE may report that two repeated PDCCH candidates should have the same aggregation level through [ UE capability reporting method 3], and may report the maximum value of the time interval between the two repeated PDCCHs as 4 OFDM symbols while supporting TDM-based PDCCH repetition transmission through [ UE capability reporting method 4 ]. In addition, applications based on various combinations of UE capability reporting methods are also possible.
< third embodiment: configuration method related to PDCCH repeated emission and explicit linking >
As an embodiment of the present disclosure, a method for configuring PDCCH repetition transmission to enable soft combining during PDCCH repetition transmission will be described. When the base station performs PDCCH repetition transmission to the UE based on method 1-1 (a method of repeatedly transmitting a plurality of PDCCHs having the same payload) among various PDCCH repetition transmission methods, in order to reduce the number of blind decodes by considering whether the UE may perform soft combining, the base station may configure information indicating that there is an explicit link or association between repeated candidate PDCCHs via higher layer signaling, which may be indicated by L1 signaling, or which may be configured and indicated by layer signaling or a combination of L1 signaling. In more detail, there may be various association methods as follows.
There may be various configuration methods related to PDCCH repetition transmission and explicit linking via higher layer signaling as follows.
[ PDCCH repetition configuration method 1] when configuration information exists in a higher layer signaling PDCCH-config
The base station may configure PDCCH-repetition-config among PDCCH-config as higher layer signaling to perform PDCCH repetition transmission and explicit link-related configuration to the UE, and the PDCCH-repetition-config may include at least one of the following information. The information listed below is not all inclusive and some information may be omitted and other information may be included.
-PDCCH repetition transmission method-one of TDM, FDM and SFN
Control resource set-search space combination to be used during PDCCH repeated transmission
■ Control resource set index-optional
■ Search space index-optional
Aggregation level for explicit linking-optional
-PDCCH candidate index for explicit linking-optional
-frequency resources for explicit linking-optional
Based on the above information, the base station may configure PDCCH for the UE to repeat transmission through higher layer signaling. For example, if the PDCCH repetition transmission method is configured through the SFN, the control resource set index is configured to be "1" as a combination of control resource set-search space to be used in PDCCH repetition transmission; and if the search space index is not configured, the UE may expect to repeatedly transmit the PDCCH in the control resource set having index 1 through methods 1-5 (SFN transmission method). Here, the configured control resource set may be configured with one or more different TCI states via higher layer signaling, which may be indicated via L1 signaling or MAC-CE signaling, or which may be configured or indicated with a combination of higher layer signaling and L1 signaling or MAC-CE signaling. In addition, if the PDCCH repetition transmission method is configured through the SFN, the UE may not expect to configure a search space index in a combination of a control resource set-search space to be used for PDCCH repetition transmission.
As another example, by configuring a PDCCH repetition transmission method through TDM or FDM, configuring a total of two combinations of control resource set-search spaces to be used in PDCCH repetition transmission, and configuring a control resource set index 1 and a search space index 1 for a first combination of control resource set-search spaces, and configuring a control resource set index 2 and a search space index 2 for a second combination of control resource set-search spaces, a ue may expect to repeatedly transmit a PDCCH using the two combinations of control resource set-search spaces through method 1-1 using a TDM or FDM scheme. Here, each configured control resource may be configured with one or more different TCI states via higher layer signaling, which may be indicated via L1 signaling or MAC-CE signaling, or which may be configured or indicated with a combination of higher layer signaling and L1 signaling or MAC-CE signaling. In addition, if the PDCCH repetition transmission method is configured through TDM or FDM, the UE may expect to configure at most two combinations of control resource sets-search spaces to be used during PDCCH repetition transmission, and may expect to configure both control resource sets and search space indexes in each combination.
In addition, the above information may have an updated value based on the MAC-CE without reconfiguring the RRC. If the base station does not configure the PDCCH-repetition-configuration for the UE, the UE does not expect the repeated transmission of PDCCH, and may expect only a single PDCCH transmission. The aggregation level, the PDCCH candidate index, and the frequency resource for the explicit link described above may not be all configured, or at least one thereof may be configured according to an explicit linking method to be described later.
PDCCH repetition configuration method 2 when configuration information exists in higher layer signaling for search space
The base station may add higher layer signaling in the searchSpace for higher layer signaling of the search space to perform PDCCH repetition transmission and provide notification thereof to the UE. For example, a parameter called "repetition" in the searchSpace as other higher layer signaling is configured as "on" or "off", and thus the corresponding search space is used for repeated transmission. For each bandwidth portion, there may be one or two search spaces for which "repetition" is configured as "on". For example, when in the searchSpace, which is higher layer signaling for the search space index 1, the searchSpace is configured to 1, the control resource set id is configured to 1, and the repetition is configured to "on", the UE may expect to perform PDCCH repetition transmission in the control resource set 1 connected to the search space 1 according to methods 1-5 (SFN transmission method).
As another example, in the searchSpace as the higher layer signaling of the search space index 1, the searchSpace is configured to 1, the control resource set id is configured to 1 and the repetition is configured to on, and in the searchSpace as the higher layer signaling of the search space index 2, the searchSpace is configured to 2, the control resource set id is configured to 2 and the repetition is configured to on, the UE may recognize that PDCCH repetition transmission is performed between the combination of the control resource set 1+search space 1 and the combination of the control resource set 2+search space 2 via TDM or FDM by using the method 1-1. TDM and FDM may be partitioned by higher layer signaling that controls resource sets 1 and 2 and search spaces 1 and 2 according to time and frequency configurations. In addition, in higher layer signaling of a search space in which repetition is configured to be on, an aggregation level of explicit links or a PDCCH candidate index specified in [ PDCCH reception configuration method 1] may be configured, and either one may not be configured, either one may be configured, or both may be configured according to an explicit link method to be described later.
In addition, in order to perform PDCCH repetition transmission and explicit link-related configuration, some configurations or operations between the above-described methods may be selectively combined/combined and applied.
< embodiment (3-1): configuration method related to single or multiple TRP-based PDCCH repeated transmission
As an embodiment of the present disclosure, when a base station performs PDCCH repetition transmission to a UE based on method 1-1 (a method of repeatedly transmitting a plurality of PDCCHs having the same payload) among various PDCCH repetition transmission methods, the base station may be configured with a combination of a control resource set-search space to be used during PDCCH repetition transmission according to [ PDCCH repetition configuration method 1] described above. In addition, the UE may receive configuration information related to PDCCH repetition in a search space to be used during PDCCH repetition transmission according to [ PDCCH repetition configuration method 2] described above. Here, the following can be considered.
Case 1 when a set of control resources configured with a TCI state is connected to two different search spaces and configured.
As an example, the following can be considered: the UE is configured with search space 1 and search space 2 from the base station and is configured with the same set of control resources connected to each search space. In this example, if the same control resource set (e.g., control resource set 1) is connected to each search space and configured, and one TCI state is configured in the control resource set 1 or activated through MAC-CE, the UE may receive PDCCH repetition transmission based on a single TRP through the corresponding control resource set. For example, in both cases where control resource set 1 is connected to search space 1 and transmitted and where control resource set 1 is connected to search space 2 and transmitted, the UE may receive control resource set 1 assuming one and the same TCI state.
Here, the base station may configure a PDCCH repetition transmission method via TDM for the UE through higher layer signaling, or may perform PDCCH repetition transmission based on a single TRP in an intra-slot or inter-slot TDM scheme by using configuration information of two different search spaces configured for PDCCH repetition transmission through higher layer signaling. Meanwhile, the base station may configure the monitoring slot period and slot offset in two different search spaces to be the same for the UE, wherein the monitoring slot period and slot offset are configuration information in the two different search spaces, and may perform PDCCH repetition transmission based on TDM within the slot based on one control resource set of the two search spaces and the connection.
Here, if the number of PDCCH monitoring positions in two search spaces within a slot is the same, the UE may assume that the PDCCH monitoring positions in two search spaces within one slot have an explicit link with each other. For example, based on configuration information of a base station, configuration information monitoringsymbols withinslot of search space 1 has "10000001000000", configuration information monitoringsymbols withinslot of search space 2 has "00010000001000", and one control resource set connected to two search spaces includes three OFDM symbols. Here, based on the configuration information, the UE may recognize that the first PDCCH monitoring position for search space 1 is provided with 3 symbols (1 to 3) from the first OFDM symbol of the corresponding slot, and the second PDCCH monitoring position for search space 1 is provided with 3 symbols (8 to 10) from the eighth OFDM symbol. In addition, through configuration information of the base station, the UE may recognize that the first PDCCH monitoring position for the search space 2 is provided with 3 symbols (4 to 6) from the fourth OFDM symbol of the corresponding slot, and the second PDCCH monitoring position for the search space 2 is provided with 3 symbols (11 to 13) from the eleventh OFDM symbol.
Here, the UE may assume that the first PDCCH monitoring locations for search space 1 and search space 2 have explicit links to each other, and that the second PDCCH monitoring locations for search space 1 and search space 2 have explicit links to each other. For example, if two search spaces have the same number of PDCCH monitoring positions within one slot, the UE may recognize that the PDCCH monitoring positions have a one-to-one connection relationship in sequence.
As another example, if two search spaces have different numbers of PDCCH monitoring locations within one slot, the UE may assume that some PDCCH monitoring locations have explicit links to each other. For example, if search space 1 and search space 2 have N and M PDCCH monitoring positions, respectively, and N < M, the UE may assume that PDCCH monitoring positions 1 to N in two search spaces have a one-to-one connection relationship in the index order of PDCCH monitoring positions 1 to N. In addition, the UE may assume that the (n+1) -th to M-th PDCCH monitoring locations for search space 2 are for single PDCCH transmission based on a single TRP without explicit linking with the PDCCH monitoring location of search space 1; it may be assumed that the (n+1) -th to M-th PDCCH monitoring positions for search space 2 have explicit links to the first to (M-N) -th PDCCH monitoring positions for search space 1, respectively; or it may be assumed that the (n+1) th to M-th PDCCH monitoring positions in search space 2 have an explicit link with the N-th PDCCH monitoring position of search space 1.
In addition, the base station may perform inter-slot PDCCH repetition transmission based on a single TRP by configuring the monitored slot periods in two different search spaces to be the same and the slot offsets in the two different search spaces to be different for the UE, wherein the monitored slot periods and the slot offsets are configuration information in the two different search spaces. For example, when the slot periods of the search space 1 and the search space 2 are configured to 2, the slot offset of the search space 1 is configured to 1, and the slot offset of the search space 2 is configured to 2, the UE may expect to perform PDCCH repetition transmission based on a single TRP between the two slots. Here, similar to the method of having an explicit link between PDCCH monitoring locations in slots, PDCCH monitoring locations in two search spaces existing in each of two slots may be assumed to have an explicit link.
In addition, the base station configures the monitoring slot period and slot offset in two different search spaces to be different for the UE, wherein the monitoring slot period and slot offset are configuration information in the two different search spaces, and thus in a specific slot, the two search spaces may be configured to have PDCCH monitoring positions, and in other slots, only one search space among the two search spaces may be configured to have a monitoring position. For example, if the slot period of search space 1 is 1 and the slot period of search space 2 is 2, the UE may have a PDCCH monitoring location of search space 1 in each slot and may have PDCCH monitoring locations of search space 1 and search space 2 in every two slots. Here, the UE may assume that a single transmission of a PDCCH based on a single TRP is performed in a slot having only a PDCCH monitoring location of search space 1, and that a repetition transmission of a PDCCH based on a single TRP is performed in a slot having both a PDCCH monitoring location of search space 1 and search space 2 (i.e., every two slots).
Case 2 when one set of control resources configured with two TCI states is connected to two different search spaces and configured.
As an example, the following can be considered: the UE is configured with search space 1 and search space 2 from the base station and is configured with the same set of control resources connected to each search space. In this example, if the same control resource set (e.g., control resource set 1) is connected to each search space and configured, and two TCI states are configured in control resource set 1 or activated through MAC-CE, the UE may receive a multi-TRP-based PDCCH repetition transmission through the corresponding control resource set. For example, in case control resource set 1 is connected to search space 1 and transmitted, the UE may receive control resource set 1 assuming a first TCI state; and in case control resource set 1 is connected to search space 2 and transmitted, the UE may receive control resource set 1 assuming a second TCI state.
Here, the base station may configure a PDCCH repetition transmission method via TDM for the UE through higher layer signaling, or may perform multi-TRP-based PDCCH repetition transmission in an intra-slot or inter-slot TDM scheme by using configuration information of two different search spaces configured for PDCCH repetition transmission through higher layer signaling. Meanwhile, the base station may configure the monitoring slot period and slot offset in two different search spaces to be the same for the UE, wherein the monitoring slot period and slot offset are configuration information in the two different search spaces, and may perform PDCCH repetition transmission based on TDM within the slot based on one control resource set of the two search spaces and the connection.
Here, if the number of PDCCH monitoring positions in two search spaces within a slot is the same, the UE may assume that the PDCCH monitoring positions in two search spaces within one slot have an explicit link with each other. For example, based on configuration information of a base station, configuration information monitoringsymbols withinslot of search space 1 has "10000001000000", configuration information monitoringsymbols withinslot of search space 2 has "00010000001000", and one control resource set connected to two search spaces includes three OFDM symbols. Here, based on the configuration information, the UE may recognize that the first PDCCH monitoring position for search space 1 is provided with 3 symbols (1 to 3) from the first OFDM symbol of the corresponding slot, and the second PDCCH monitoring position for search space 1 is provided with 3 symbols (8 to 10) from the eighth OFDM symbol. In addition, through configuration information of the base station, the UE may recognize that the first PDCCH monitoring position for the search space 2 is provided with 3 symbols (4 to 6) from the fourth OFDM symbol of the corresponding slot, and the second PDCCH monitoring position for the search space 2 is provided with 3 symbols (11 to 13) from the eleventh OFDM symbol.
Here, the UE may assume that the first PDCCH monitoring locations for search space 1 and search space 2 have explicit links to each other, and that the second PDCCH monitoring locations for search space 1 and search space 2 have explicit links to each other. For example, if two search spaces have the same number of PDCCH monitoring positions within one slot, the UE may recognize that the PDCCH monitoring positions have a one-to-one connection relationship in sequence.
As another example, if two search spaces have different numbers of PDCCH monitoring locations within one slot, the UE may assume that some PDCCH monitoring locations have explicit links to each other. For example, if search space 1 and search space 2 have N and M PDCCH monitoring positions, respectively, and N < M, the UE may assume that PDCCH monitoring positions 1 to N in two search spaces have a one-to-one connection relationship in the index order of PDCCH monitoring positions 1 to N. In addition, the UE may assume that the (n+1) -th to M-th PDCCH monitoring locations for search space 2 are for single PDCCH transmission based on a single TRP without explicit linking with the PDCCH monitoring location of search space 1; it may be assumed that the (n+1) -th to M-th PDCCH monitoring positions for search space 2 have explicit links to the first to (M-N) -th PDCCH monitoring positions for search space 1, respectively; or it may be assumed that the (n+1) th to M-th PDCCH monitoring positions in search space 2 have an explicit link with the N-th PDCCH monitoring position of search space 1.
Here, as described above, the first TCI state of the control resource set may be applied to the PDCCH monitoring location of the search space 1, the second TCI state may be applied to the PDCCH monitoring location of the search space 2, or the first TCI state and the second TCI state may be applied to the PDCCH monitoring location of the search space 1 or the search space 2 alternately with each other.
In addition, the base station may perform inter-slot PDCCH repetition transmission based on the multi-TRP by configuring the monitored slot periods in the two different search spaces to be the same and the slot offsets in the two different search spaces to be different for the UE, wherein the monitored slot periods and the slot offsets are configuration information in the two different search spaces. For example, when the slot periods of the search space 1 and the search space 2 are configured to 2, the slot offset of the search space 1 is configured to 1, and the slot offset of the search space 2 is configured to 2, the UE may expect to perform PDCCH repetition transmission based on a single TRP between the two slots. Here, similar to the method of having an explicit link between PDCCH monitoring locations in slots, PDCCH monitoring locations in two search spaces existing in each of two slots may be assumed to have an explicit link.
In addition, the base station configures the monitoring slot period and slot offset in two different search spaces to be different for the UE, wherein the monitoring slot period and slot offset are configuration information in the two different search spaces, and thus in a specific slot, the two search spaces may be configured to have PDCCH monitoring positions, and in other slots, only one search space among the two search spaces may be configured to have a monitoring position. For example, if the slot period of search space 1 is 1 and the slot period of search space 2 is 2, the UE may have a PDCCH monitoring location of search space 1 in each slot and may have PDCCH monitoring locations of search space 1 and search space 2 in every two slots. Here, the UE may assume that a single transmission of a PDCCH based on a single TRP is performed in a slot having only a PDCCH monitoring location of search space 1, and that repeated transmission of a PDCCH based on multiple TRP is performed in a slot having both PDCCH monitoring locations of search space 1 and search space 2 (i.e., every two slots).
Case 3 when two control resource sets configured with the same TCI state are connected to two different search spaces and configured, respectively.
As an example, the following can be considered: the UE is configured with search space 1 and search space 2 from the base station and is configured with a different set of control resources connected to each search space. In this example, if a different control resource set is connected to each search space (e.g., control resource set 1 and control resource set 2 are connected to search space 1 and search space 2, respectively), and control resource set 1 and control resource set 2 are configured with one and the same TCI state or the TCI state is activated through MAC-CE, the UE may receive PDCCH repetition transmission based on a single TRP through the corresponding control resource set. For example, in both cases where control resource set 1 is connected to search space 1 and transmitted and where control resource set 2 is connected to search space 2 and transmitted, the UE may receive control resource set 1 and/or control resource set 2 assuming one and the same TCI state.
Here, the base station may configure a PDCCH repetition transmission method via TDM for the UE through higher layer signaling, or may perform PDCCH repetition transmission based on a single TRP in an intra-slot or inter-slot TDM scheme by using configuration information of two different search spaces configured for PDCCH repetition transmission through higher layer signaling. Meanwhile, the base station may configure the monitoring slot period and slot offset in two different search spaces to be the same for the UE, wherein the monitoring slot period and slot offset are configuration information in the two different search spaces, and may perform PDCCH repetition transmission based on intra-slot TDM based on the two different search spaces and the connected two different control resource sets.
Here, if the number of PDCCH monitoring positions in two search spaces within a slot is the same, the UE may assume that the PDCCH monitoring positions in two search spaces within one slot have an explicit link with each other. For example, based on configuration information of a base station, configuration information monitoringsymbols withinslot of search space 1 has "10000001000000", configuration information monitoringsymbols withinslot of search space 2 has "00010000001000", and two control resource sets connected to two search spaces include three OFDM symbols. Here, based on the configuration information, the UE may recognize that the first PDCCH monitoring position for search space 1 is provided with 3 symbols (1 to 3) from the first OFDM symbol of the corresponding slot, and the second PDCCH monitoring position for search space 1 is provided with 3 symbols (8 to 10) from the eighth OFDM symbol. In addition, through configuration information of the base station, the UE may recognize that the first PDCCH monitoring position for the search space 2 is provided with 3 symbols (4 to 6) from the fourth OFDM symbol of the corresponding slot, and the second PDCCH monitoring position for the search space 2 is provided with 3 symbols (11 to 13) from the eleventh OFDM symbol.
Here, the UE may assume that the first PDCCH monitoring locations for search space 1 and search space 2 have explicit links to each other, and that the second PDCCH monitoring locations for search space 1 and search space 2 have explicit links to each other. For example, if two search spaces have the same number of PDCCH monitoring positions within one slot, the UE may recognize that the PDCCH monitoring positions have a one-to-one connection relationship in sequence.
As another example, if two search spaces have different numbers of PDCCH monitoring locations within one slot, the UE may assume that some PDCCH monitoring locations have explicit links to each other. For example, if search space 1 and search space 2 have N and M PDCCH monitoring positions, respectively, and N < M, the UE may assume that PDCCH monitoring positions 1 to N in two search spaces have a one-to-one connection relationship in the index order of PDCCH monitoring positions 1 to N. In addition, the UE may assume that the (n+1) -th to M-th PDCCH monitoring locations for search space 2 are for single PDCCH transmission based on a single TRP without explicit linking with the PDCCH monitoring location of search space 1; it may be assumed that the (n+1) -th to M-th PDCCH monitoring positions for search space 2 have explicit links to the first to (M-N) -th PDCCH monitoring positions for search space 1, respectively; or it may be assumed that the (n+1) th to M-th PDCCH monitoring positions of search space 2 have an explicit link with the N-th PDCCH monitoring position of search space 1.
In addition, the base station may perform inter-slot PDCCH repetition transmission based on a single TRP by configuring the monitored slot periods in two different search spaces to be the same and the slot offsets in the two different search spaces to be different for the UE, wherein the monitored slot periods and the slot offsets are configuration information in the two different search spaces. For example, when the slot periods of the search space 1 and the search space 2 are configured to 2, the slot offset of the search space 1 is configured to 1, and the slot offset of the search space 2 is configured to 2, the UE may expect to perform PDCCH repetition transmission based on a single TRP between the two slots. Here, similar to the method of having an explicit link between PDCCH monitoring locations in slots, PDCCH monitoring locations in two search spaces existing in each of two slots may be assumed to have an explicit link.
In addition, the base station configures the monitoring slot period and slot offset in two different search spaces to be different for the UE, wherein the monitoring slot period and slot offset are configuration information in the two different search spaces, and thus in a specific slot, the two search spaces may be configured to have PDCCH monitoring positions, and in other slots, only one search space among the two search spaces may be configured to have a monitoring position. For example, if the slot period of search space 1 is 1 and the slot period of search space 2 is 2, the UE may have a PDCCH monitoring location of search space 1 in each slot and may have PDCCH monitoring locations of search space 1 and search space 2 in every two slots. Here, the UE may assume that a single transmission of a PDCCH based on a single TRP is performed in a slot having only a PDCCH monitoring location of search space 1, and that a repetition transmission of a PDCCH based on a single TRP is performed in a slot having both a PDCCH monitoring location of search space 1 and search space 2 (i.e., every two slots).
Case 4 when two sets of control resources configured with different TCI states are connected to two different search spaces and are configured.
As an example, the following can be considered: the UE is configured with search space 1 and search space 2 from the base station and is configured with a different set of control resources connected to each search space. In this example, if a different set of control resources is connected to each search space (e.g., set of control resources 1 and set of control resources 2 are connected to search space 1 and search space 2, respectively), and set of control resources 1 and set of control resources 2 are configured with one different TCI state or activated by MAC-CE (e.g., when TCI state 1 is configured in set of control resources 1 or activated by MAC-CE, and TCI state 2 is configured in set of control resources 2 or activated by MAC-CE), the UE may receive a multi-TRP based PDCCH repetition transmission through the corresponding set of control resources. For example, in case control resource set 1 is connected to search space 1 and transmitted, the UE may receive control resource set 1 assuming a first TCI state; and in case control resource set 2 is connected to search space 2 and transmitted, the UE may receive control resource set 2 assuming a second TCI state.
Here, the base station may configure a PDCCH repetition transmission method via TDM for the UE through higher layer signaling, or may perform PDCCH repetition transmission in an intra-slot or inter-slot TDM scheme by using configuration information of two different search spaces configured for PDCCH repetition transmission through higher layer signaling. Meanwhile, the base station may configure the monitoring slot period and slot offset in two different search spaces to be the same for the UE, wherein the monitoring slot period and slot offset are configuration information in the two different search spaces, and may perform PDCCH repetition transmission based on intra-slot TDM based on the two different search spaces and the connected two different control resource sets.
Here, if the number of PDCCH monitoring positions in two search spaces within a slot is the same, the UE may assume that the PDCCH monitoring positions in two search spaces within one slot have an explicit link with each other. For example, based on configuration information of a base station, configuration information monitoringsymbols withinslot of search space 1 has "10000001000000", configuration information monitoringsymbols withinslot of search space 2 has "00010000001000", and each of control resource sets connected to two search spaces may include three OFDM symbols. Here, based on the configuration information, the UE may recognize that the first PDCCH monitoring position for search space 1 is provided with 3 symbols (1 to 3) from the first OFDM symbol of the corresponding slot, and the second PDCCH monitoring position for search space 1 is provided with 3 symbols (8 to 10) from the eighth OFDM symbol. In addition, through configuration information of the base station, the UE may recognize that the first PDCCH monitoring position for the search space 2 is provided with 3 symbols (4 to 6) from the fourth OFDM symbol of the corresponding slot, and the second PDCCH monitoring position for the search space 2 is provided with 3 symbols (11 to 13) from the eleventh OFDM symbol.
Here, the UE may assume that the first PDCCH monitoring locations for search space 1 and search space 2 have explicit links to each other, and that the second PDCCH monitoring locations for search space 1 and search space 2 have explicit links to each other. For example, if two search spaces have the same number of PDCCH monitoring positions within one slot, the UE may recognize that the PDCCH monitoring positions have a one-to-one connection relationship in sequence.
As another example, if two search spaces have different numbers of PDCCH monitoring locations within one slot, the UE may assume that some PDCCH monitoring locations have explicit links to each other. For example, if search space 1 and search space 2 have N and M PDCCH monitoring positions, respectively, and N < M, the UE may assume that PDCCH monitoring positions 1 to N in two search spaces have a one-to-one connection relationship in the index order of PDCCH monitoring positions 1 to N. In addition, the UE may assume that the (n+1) -th to M-th PDCCH monitoring locations for search space 2 are for single PDCCH transmission based on a single TRP without explicit linking with the PDCCH monitoring location of search space 1; it may be assumed that the (n+1) -th to M-th PDCCH monitoring positions for search space 2 have explicit links to the first to (M-N) -th PDCCH monitoring positions for search space 1, respectively; or it may be assumed that the (n+1) th to M-th PDCCH monitoring positions of search space 2 have an explicit link with the N-th PDCCH monitoring position of search space 1.
In addition, the base station may perform inter-slot PDCCH repetition transmission based on the multi-TRP by configuring the monitored slot periods in the two different search spaces to be the same and the slot offsets in the two different search spaces to be different for the UE, wherein the monitored slot periods and the slot offsets are configuration information in the two different search spaces. For example, when the slot periods of search space 1 and search space 2 are configured to 2, the slot offset of search space 1 is configured to 1, and the slot offset of search space 2 is configured to 2, the UE may expect to perform PDCCH repetition transmission between the two slots. Here, similar to the method of having an explicit link between PDCCH monitoring locations in slots, PDCCH monitoring locations in two search spaces existing in each of two slots may be assumed to have an explicit link.
In addition, the base station configures the monitoring slot period and slot offset in two different search spaces to be different for the UE, wherein the monitoring slot period and slot offset are configuration information in the two different search spaces, and thus in a specific slot, the two search spaces may be configured to have PDCCH monitoring positions, and in other slots, only one search space among the two search spaces may be configured to have a monitoring position. For example, if the slot period of search space 1 is 1 and the slot period of search space 2 is 2, the UE may have a PDCCH monitoring location of search space 1 in each slot and may have PDCCH monitoring locations of search space 1 and search space 2 in every two slots. Here, the UE may assume that a single transmission of a PDCCH based on a single TRP is performed in a slot having only a PDCCH monitoring location of search space 1, and that repeated transmission of a PDCCH based on multiple TRP is performed in a slot having both PDCCH monitoring locations of search space 1 and search space 2 (i.e., every two slots).
Meanwhile, for technical convenience, it is assumed that at most two search spaces, control resource sets, or TCI states are configured for the above-described combination of control resource sets-search spaces. However, the above method may be applied even when two or more search spaces, control resource sets, or TCI states are configured. In addition, in this case, the above methods may be selectively combined. In addition, although the above method is mainly described with respect to the TDM scheme, it may be applied to a method of PDCCH repetition transmission through the FDM scheme according to the configuration information in the search space and the control resource set.
< fourth embodiment: PDCCH repeated transmission configuration method considering soft combining during PDCCH repeated transmission >
In the 5G wireless communication system, information related to the PDCCH may have different degrees of freedom to have a specific value. In particular, the parameters present to obtain inter-cell interference control, diversity performance improvement, or scheduling gain, etc., may have different values for each set of control resources, each search space, each slot, or each OFDM symbol in a slot. Table 29 below shows configuration information related to the PDCCH, which has a degree of freedom level or in which resource unit the information has randomization or may be initialized.
TABLE 29
As an example in table 29, the PDCCH scrambling sequence may have different values according to different sets of control resources according to a higher layer signaling configuration, and the scrambling sequence of PDCCH DMRS may have different values according to different sets of control resources according to a higher layer signaling configuration, and may also have different values in different slots and different OFDM symbols. In addition, according to higher-level configuration information in the control resource set or in the search space, the following can be freely configured for each control resource set and each search space: the location of the resource set on the frequency domain, whether interleaving is performed, the unit of precoding, the aggregation level of the search space and the number of PDCCH candidates, and the location of the start symbol in the slot of the search space, the number of slots occurring consecutively, and the period of the slot are controlled.
Based on the information configured by the base station for PDCCH retransmission, the UE may receive PDCCH retransmission, where the UE may determine, depending on UE capabilities or implementation, whether to perform individual single decoding of PDCCH retransmission, whether to perform soft combining, and even at which level to perform soft combining if soft combining is performed. Thus, the base station may need to configure some of the configuration information related to the PDCCH described above according to the limitations of UE capabilities related to soft combining.
Hereinafter, according to the detailed description of the second embodiment, specific restrictions on information from a base station to a UE configured via higher layer signaling will be described in detail according to [ UE capability reporting method 1] and [ UE capability reporting method 2] related to soft combining of the UE. According to [ UE capability reporting method 3], the UE reports restrictions required by the UE during PDCCH repetition transmission configuration through capability reporting, and thus the base station can naturally configure PDCCH repetition transmission based on the corresponding restrictions, a detailed description of which will be omitted. According to the above-described [ UE capability reporting method 4], the UE reports the supported PDCCH repeated transmission configuration method through capability reporting, and detailed description similar to [ UE capability reporting method 3] will be omitted.
If the base station performs configuration such that the information reported through [ UE capability reporting method 1] to [ UE capability reporting method 4] does not match, the UE may ignore the corresponding configuration and not receive the two PDCCHs during the PDCCH repetition transmission, may select one of the PDCCHs and not receive the PDCCH, or may perform separate decoding for each PDCCH (such as a single transmission) only even in the case of the PDCCH repetition transmission.
< embodiment (4-1): PDCCH repeated emission configuration restriction according to UE capability reporting method 1 >
According to [ UE capability reporting method 1], the UE may report to the base station UE capabilities related only to whether soft combining is possible during PDCCH repetition transmission in a possible or impossible form, and the base station may receive the corresponding UE capabilities and then may inform the UE of PDCCH repetition configuration related information as follows.
[ determination 1 by base station according to UE capability reporting method 1]
As an example, if the UE reports information indicating that soft combining is possible during PDCCH repetition transmission as UE capability to the base station, the base station may most flexibly determine whether soft combining is possible for the UE (e.g., the UE determines that soft combining is possible at a level of Log Likelihood Ratio (LLR)), and may notify the UE of the configuration related to PDCCH repetition transmission as flexibly as possible during PDCCH transmission related configuration. Here, as an example related to PDCCH repetition configuration, for a UE, a base station assumes that soft combining between control resource sets or search spaces having different configurations, soft combining between candidate PDCCHs having the same aggregation level, or soft combining between candidate PDCCHs having different aggregation levels is possible, and may notify the UE of the corresponding configuration. More specifically, since the base station assumes that the UE may perform the most flexible soft combining, the base station may notify the UE of higher layer signaling with the highest degree of freedom for the information in the above table 29.
If the base station intends to configure PDCCH repetition transmission based on an intra-slot TDM scheme for the UE, the base station may configure monitoring slot periods and slot offsets (e.g., monitoringslotperiodic and offset) as configuration information and the number of consecutive slots (e.g., duration) for monitoring in different search spaces to be the same; and for both search spaces, the position of the starting OFDM symbol of the control resource set in the slot (e.g., monitoringsymbol withinslot) may be configured to not overlap on the OFDM symbols according to the OFDM symbol length of each control resource set connected to both search spaces. For example, monitoringsymbols withinslot of search space set 1 is configured as "10000000000000", OFDM symbol length of control resource set 1 connected to search space 1 is 3, monitoringsymbols withinslot of search space 2 is configured as "00000100000000", and OFDM symbol length of control resource set 2 connected to search space 1 is 3, the ue may expect control resource set 1 connected to search space 1 to exist in first to third OFDM symbols in a slot monitoring two search spaces, and control resource set 2 connected to search space 2 to exist in sixth to eighth OFDM symbols.
If the base station intends to configure PDCCH repetition transmission based on an inter-slot TDM scheme for the UE, the base station may configure a monitoring slot period and slot offset (e.g., monitoringSlotPeriodicityAndOffset) as configuration information to be the same and different in monitoring slot periods in different search spaces, may configure the number of consecutive slots (e.g., duration) for monitoring to be the same or configure two repeated PDCCHs to not be in the same slot by considering monitoringSlotPeriodicityAndOffset, and may freely configure the position of a starting OFDM symbol of a control resource set in a slot (e.g., monitoringsymbolswisloop) without limitation.
If the base station intends to configure PDCCH repetition transmission for the UE based on the FDM scheme, the base station may perform configuration for two control resource sets configured for PDCCH repetition transmission such that frequency resource positions (e.g., frequency domain resources) as higher layer configurations in the control resource set configuration do not overlap with each other. For example, by configuring a bitmap of frequencydomalnresource as a mutually exclusive bitmap associated with configuration information of two control resource sets, a base station may perform PDCCH repetition transmission to a UE through an FDM scheme. For example, if there is a predetermined bitmap for frequencydomalnresources associated with control resource set 1, frequencydomalnresources associated with the remaining control resource set 2 may have a form in which bits are shifted in a particular direction with respect to frequencydomalnresources associated with control resource set 1. More specifically, if the frequencyDomainResources of control resource set 1 has bitmaps with MSB 1 to MSB 5 of 1 and the remaining bits of 0, the frequencyDomainResources of control resource set 2 may be bitmaps with MSB 8 to MSB 12 of 1 and the remaining bits of 0, and this may be regarded as a form in which the frequencyDomainResources of control resource set 1 are shifted by 7.
[ determination 1 by base station according to UE capability reporting method 2 ]
As another example, if the UE reports to the base station information that soft combining is possible during PDCCH repetition transmission as UE capability, the base station may most conservatively determine the level of soft combining possible by the UE (e.g., determine that soft combining is possible by the UE on the OFDM symbol level) and may notify the UE of the configuration related to PDCCH repetition transmission in the most restrictive manner during PDCCH transmission related configuration. Here, as an example related to PDCCH repetition configuration, the base station may assume that soft combining between a plurality of control resource sets having the same configuration or soft combining between candidate PDCCHs having the same aggregation level is possible for the UE, and may notify the UE of the corresponding configuration. More specifically, the base station may assume that soft combining, which is most restrictive for the UE, is also possible and thus has the lowest degree of freedom for the information in table 29, and may inform the UE of higher layer signaling.
If the base station configures the UE with the PDCCH repetition transmission method via TDM through higher layer signaling and also configures a combination of the control resource set+search space in which the PDCCH repetition transmission is to be performed through higher layer signaling, the base station may need to set a limit such that at least one of the following information for information between the two control resource sets is the same to enable soft combining in the UE.
PDCCH-DMRS-scrambling ID for each control resource set of PDCCH scrambling ID and PDCCH DMRS scrambling ID
Aggregation level as a higher layer configuration in the search space, number of PDCCH candidates per aggregation level, and maximum of number of PDCCH candidates per aggregation level
Frequency resource location (e.g., frequencydomain resources) configured as a higher layer in a control resource set, the number of OFDM symbols in a control resource set (e.g., duration), CCE-REG mapping method of a control resource set (e.g., CCE-REG-MappingType), precoder application unit (e.g., precoding granularity)
The information to be provided below may be information for which a specific constraint should exist, not just the same information.
If the base station intends to configure PDCCH repetition transmission based on an intra-slot TDM scheme for the UE, the base station may configure monitoring slot periods and slot offsets (e.g., monitoringslotperiodic and offset) as configuration information and the number of consecutive slots (e.g., duration) for monitoring in different search spaces to be the same; and for both search spaces, the position of the starting OFDM symbol of the control resource set in the slot (e.g., monitoringsymbol withinslot) may be configured to not overlap on the OFDM symbols according to the OFDM symbol length of each control resource set connected to both search spaces. For example, monitoringsymbols withinslot of search space set 1 is configured as "10000000000000", OFDM symbol length of control resource set 1 connected to search space 1 is 3, monitoringsymbols withinslot of search space 2 is configured as "00000100000000", and OFDM symbol length of control resource set 2 connected to search space 1 is 3, the ue may expect control resource set 1 connected to search space 1 to exist in first to third OFDM symbols in a slot for monitoring two search spaces, and control resource set 2 connected to search space 2 to exist in sixth to eighth OFDM symbols. In addition, since the PDCCH DMRS scrambling sequence has randomness for each OFDM symbol, the UE may expect to configure the same pdcch-DMRS-scrambling id value for both control resource sets for the PDCCH DMRS scrambling sequence. In addition, the UE may use equation 4 by repositioning it to a new function that takes information such as monitoringsymbol wiswisthinslot as input.
If the base station intends to configure PDCCH repetition transmission based on an inter-slot TDM scheme for the UE, the base station may configure a monitoring slot period and slot offset (e.g., monitoringSlotPeriodicityAndOffset) as configuration information to be the same and different in monitoring slot periods in different search spaces, may configure the number of consecutive slots (e.g., duration) for monitoring to be the same or configure two repeated PDCCHs to not be in the same slot by considering monitoringSlotPeriodicityAndOffset, and may freely configure the position of a starting OFDM symbol of a control resource set in a slot (e.g., monitoringsymbolswisloop) without limitation. In addition, since the PDCCH DMRS scrambling sequence has randomness for each slot and each OFDM symbol, the UE can expect to configure the same pdcch-DMRS-scrambling id value for the two control resource sets described above for the PDCCH DMRS scrambling sequence. In addition, the UE may use equation 4 by redefining it as a new function that takes as input information such as OFDM symbol position represented by monitoringsymbols within slot in a slot and slot offset represented by monitoringslot periodic and offset. In addition, for the hash function for each search space represented by equation 2 above, due to According to A p And has a different value for each slot and thus may have the same a p The index p of two different sets of control resources of values may be used for PDCCH repetition transmissions. For example, PDCCH repetition transmission may be performed in an inter-slot TDM scheme using a combination of p, which may have the same p mod 3, e.g., two control resource sets corresponding to p=0, 3, or p=1, 4.
If the base station configures the UE with the PDCCH repetition transmission method using FDM through higher layer signaling and also configures a combination of a control resource set+search space in which PDCCH repetition transmission is to be performed via higher layer signaling, the base station may need to set restrictions such that at least one of the following information for information between the two control resource sets is the same to enable soft combining in the UE.
PDCCH-DMRS-scrambling ID for each control resource set of PDCCH scrambling ID and PDCCH DMRS scrambling ID
Aggregation level as a higher layer configuration in the search space, number of PDCCH candidates per aggregation level, maximum number of PDCCH candidates per aggregation level, monitoring slot period and slot offset (e.g., monitoringSlotPeriodicityAndOffset), number of consecutive slots for monitoring (e.g., duration), and location of the starting OFDM symbol of the control resource set in the slot (e.g., monitoringsymbol witlinslot)
-number of OFDM symbols (e.g. duration) of control resource set in control resource set, CCE-REG mapping method (e.g. CCE-REG-MappingType) of control resource set, precoder application unit (e.g. precoding granularity)
The information to be shown below may be information for which a specific constraint should exist, not just the same information.
The base station may perform configuration for two control resource sets configured for PDCCH repetition transmission such that frequency resource positions (e.g., frequencydomain resources) as higher layer configurations in the control resource set configuration do not overlap with each other. For example, by configuring a bitmap of frequencydomalnresource as a mutually exclusive bitmap associated with configuration information of two control resource sets, a base station may perform PDCCH repetition transmission to a UE through an FDM scheme. For example, if there is a predetermined bitmap for frequencydomalnresources associated with control resource set 1, frequencydomalnresources associated with the remaining control resource set 2 may have a form in which bits are shifted in a particular direction with respect to frequencydomalnresources associated with control resource set 1. More specifically, if the frequencyDomainResources of control resource set 1 has bitmaps with MSB 1 to MSB 5 of 1 and the remaining bits of 0, the frequencyDomainResources of control resource set 2 may be bitmaps with MSB 8 to MSB 12 of 1 and the remaining bits of 0, and this may be regarded as a form in which the frequencyDomainResources of control resource set 1 are shifted by 7.
In addition, when PDCCH DMRS is mapped to the frequency position of each control resource set such that the scrambling sequences of PDCCH DMRS of the two control resource sets are identical, the base station may adjust the PDCCH DMRS value mapped to the frequency position based on the frequencydomain resources information of the two control resource sets.
< embodiment (4-2): PDCCH repeated emission configuration restriction according to UE capability reporting method 2 >
The base station may provide a restriction on PDCCH reception configuration according to [ UE capability reporting method 2] to report the possible level of soft combining in the UE.
[ base station configuration for UE capable of Soft combining at OFDM symbol level ]
Similar to [ base station according to determination 1 by UE capability reporting method 1] of the (4-1) th embodiment, if the UE has reported that soft combining on the OFDM symbol level is possible based on [ UE capability reporting method 2], the base station assumes that the UE is likely to perform the most restrictive soft combining and thus can notify the UE of higher layer signaling with the lowest degree of freedom for the information in table 29.
[ base station configuration for UE capable of Soft combining at modulation symbol level ]
If the UE has reported that soft combining at the modulation symbol level is possible based on [ UE capability reporting method 2], the base station assumes that the UE may be partially flexible soft combining and may be informed of higher layer signaling with a constraint on some of the information in table 29.
If the base station configures the UE with the PDCCH repetition transmission method via TDM through higher layer signaling and also configures a combination of the control resource set+search space in which the PDCCH repetition transmission is to be performed through higher layer signaling, the base station may need to set restrictions such that at least one of the following pieces of information about information between the two control resource sets is the same to enable soft combining in the UE.
PDCCH-DMRS-scrambling ID for each control resource set of PDCCH scrambling ID and PDCCH DMRS scrambling ID
Aggregation level as a higher layer configuration in the search space, number of PDCCH candidates per aggregation level, and maximum of number of PDCCH candidates per aggregation level
Control the number of OFDM symbols (e.g. duration) in the resource set
Unlike the case of [ base station configuration for UE capable of soft combining on OFDM symbol level ], for two control resource sets where PDCCH repetition transmission occurs, frequency resource locations (e.g., frequency domain resources) configured as a higher layer in each control resource set may have the same number of CCEs but different locations on the frequency domain, and CCE-REG mapping methods (e.g., CCE-REG-MappingType) and precoder application units (e.g., precoder granularity) of the control resource sets may be configured differently.
The information to be shown below may be information for which there should be a specific limitation, not just the same information.
If the base station intends to configure PDCCH repetition transmission based on an intra-slot TDM scheme for the UE, the base station may configure monitoring slot periods and slot offsets (e.g., monitoringslotperiodic and offset) as configuration information and the number of consecutive slots (e.g., duration) for monitoring in different search spaces to be the same; and for both search spaces, the position of the starting OFDM symbol of the control resource set in the slot (e.g., monitoringsymbol withinslot) may be configured to not overlap on the OFDM symbols according to the OFDM symbol length of each control resource set connected to both search spaces. For example, monitoringsymbols withinslot of search space set 1 is configured as "10000000000000", OFDM symbol length of control resource set 1 connected to search space 1 is 3, monitoringsymbols withinslot of search space 2 is configured as "00000100000000", and OFDM symbol length of control resource set 2 connected to search space 1 is 3, the ue may expect control resource set 1 connected to search space 1 to exist in first to third OFDM symbols in a slot for monitoring two search spaces, and control resource set 2 connected to search space 2 to exist in sixth to eighth OFDM symbols.
If the base station intends to configure PDCCH repetition transmission based on an inter-slot TDM scheme for the UE, the base station may configure a monitoring slot period and slot offset (e.g., monitoringSlotPeriodicityAndOffset) as configuration information to be the same and different in monitoring slot periods in different search spaces, may configure the number of consecutive slots (e.g., duration) for monitoring to be the same or configure two repeated PDCCHs to not be in the same slot by considering monitoringSlotPeriodicityAndOffset, and may freely configure the position of a starting OFDM symbol of a control resource set in a slot (e.g., monitoringsymbolswisloop) without limitation.
If the base station configures the UE with the PDCCH repetition transmission method using FDM through higher layer signaling and also configures a combination of a control resource set+search space in which PDCCH repetition transmission is to be performed via higher layer signaling, the base station may need to set restrictions such that at least one of the following information for information between the two control resource sets is the same to enable soft combining in the UE.
PDCCH-DMRS-scrambling ID for each control resource set of PDCCH scrambling ID and PDCCH DMRS scrambling ID
Aggregation level as a higher layer configuration in the search space, number of PDCCH candidates per aggregation level, maximum number of PDCCH candidates per aggregation level, monitoring slot period and slot offset (e.g., monitoringSlotPeriodicityAndOffset), number of consecutive slots for monitoring (e.g., duration), and location of the starting OFDM symbol of the control resource set in the slot (e.g., monitoringsymbol witlinslot)
-number of OFDM symbols (e.g. duration) of control resource set in control resource set
Unlike the case of [ base station configuration for UE capable of soft combining on OFDM symbol level ], CCE-REG mapping method (e.g., cc-REG-MappingType) and precoder application unit (e.g., precoding granularity) of the control resource set may be configured differently.
The information to be shown below may be information for which a specific constraint should exist, not just the same information.
The base station may perform configuration for two control resource sets configured for PDCCH repetition transmission such that frequency resource positions (e.g., frequencydomain resources) as higher layer configurations in the control resource set configuration do not overlap with each other. For example, by configuring a bitmap of frequencydomalnresource as a mutually exclusive bitmap associated with configuration information of two control resource sets, a base station may perform PDCCH repetition transmission to a UE through an FDM scheme. For example, if there is a predetermined bitmap for frequencydomalnresources associated with control resource set 1, frequencydomalnresources associated with the remaining control resource set 2 may have a form in which bits are shifted in a particular direction with respect to frequencydomalnresources associated with control resource set 1. More specifically, if the frequencyDomainResources of control resource set 1 has bitmaps with MSB 1 to MSB 5 of 1 and the remaining bits of 0, the frequencyDomainResources of control resource set 2 may be bitmaps with MSB 8 to MSB 12 of 1 and the remaining bits of 0, and this may be regarded as a form in which the frequencyDomainResources of control resource set 1 are shifted by 7.
In addition, when PDCCH DMRS is mapped to the frequency position of each control resource set such that the scrambling sequences of PDCCH DMRS of the two control resource sets are identical, the base station may adjust the PDCCH DMRS value mapped to the frequency position based on the frequencydomain resources information of the two control resource sets.
[ base station configuration for UE capable of Soft combining on LLR level ]
Similar to the [ determination 2 by the base station according to UE capability reporting method 1 ] of the (4-1) th embodiment, if the UE has reported that soft combining on the LLR level is possible based on the [ UE capability reporting method 2], the base station assumes that the UE is likely to perform the most flexible soft combining and thus can notify the UE of higher layer signaling with the highest degree of freedom for the information of table 29.
In addition, some configurations or operations between the above-described methods may be selectively combined/combined and applied to perform configuration of PDCCH repeated transmission in consideration of soft combining during PDCCH repeated transmission.
Fig. 17 shows a flowchart of UE capability reporting during PDCCH repetition transmission and UE operation according to a PDCCH repetition transmission configuration of a base station according to an embodiment of the present disclosure. This is for ease of explanation and not necessarily all operations described below are included, and some operations may be omitted, depending on the configuration and/or definition on the system.
Referring to fig. 17, in operation 1700, a UE may report UE capabilities related to PDCCH repetition transmission to a base station. Here, the possible UE capability report may be at least one of a PDCCH repeated transmission method supported by the UE (for example, may be one of methods 1-1 to 1-5), and a UE capability reporting method related to soft combining (whether soft combining is possible, a possible level of soft combining, a limitation required for soft combining, etc.) considered in the second embodiment, or a part thereof. In another embodiment, operation 1700 may be omitted when information about UE capabilities is preconfigured for the corresponding UE. In addition, when information on UE capabilities is equally applied to a predetermined group of UEs as default information, operation 1700 may be omitted.
Thereafter, in operation 1701, the UE may receive first configuration information for PDCCH from the base station, and in operation 1702, may also receive second configuration information for PDCCH repetition transmission. Here, the second configuration information may include information about at least one of: repeated transmission method, number of repeated transmissions, repeated transmission interval, repeated transmission period, PDCCH monitoring opportunity assuming repeated transmission, whether link or association between repeated transmissions can be checked, and information on control resource set+search space configured with repeated transmission. In addition, the UE may also receive third configuration information in operation 1703. Here, the third configuration information may include information on at least one of an aggregation level, a PDCCH candidate set, and frequency resources, or may not configure any one thereof according to the method of the third embodiment. In addition, the UE may receive at least a portion of the first to third configuration information through L1 signaling, or may implicitly determine at least a portion thereof based on other configuration information. In addition, the first to third configuration information may be included in one configuration information and provided to the UE.
Upon receiving the configuration information, the UE recognizes that transmission is performed using a plurality of control resource sets+search spaces configured with repeated transmission by the base station in operation 1704, and if the UE receives the PDCCH using a control resource set and/or a search space other than the control resource set+search space configured with repeated transmission, the procedure proceeds to operation 1707, and the UE may perform an operation using a single PDCCH reception and a single decoding (a third reception operation) as an existing PDCCH reception operation. Meanwhile, if the UE receives the PDCCH using the control resource set+search space configured with repeated transmissions in operation 1704, the UE may compare the reported UE capability with the base station configuration to determine that the base station configuration is a configuration method in which the UE may perform reception by reflecting the UE capability in operation 1708, e.g., if it may be determined that the base station configuration matches the UE capability report, the process proceeds to operation 1705 to perform the first reception operation in operation 1705. The first receiving operation can be understood as: the UE may determine that repeated transmission of the PDCCH is performed by the base station according to the configuration information and using a single PDCCH receiving method as an existing PDCCH receiving operation, or perform soft combining between candidate PDCCHs that are assumed to be capable of soft combining and explicitly connected to each other. Meanwhile, if it is determined in operation 1708 that the base station configuration does not match the UE capability report, the UE may perform a second reception operation in operation 1706. The second receiving operation can be understood as: as described above, the UE ignores the configuration of the base station and does not receive two PDCCHs during PDCCH repetition transmission, or selects either one of the two PDCCHs and does not receive, or performs individual decoding only on each PDCCH as if a single transmission is performed even if PDCCH repetition transmission is performed.
Fig. 18 illustrates a flowchart of UE capability reporting during PDCCH repetition transmission and base station operation according to a PDCCH repetition transmission configuration of a base station according to an embodiment of the present disclosure. This is for convenience of explanation, and not necessarily including all operations described below, and some operations may be omitted, depending on the configuration and/or definition of the system.
Referring to fig. 18, in operation 1800, a base station may receive UE capabilities related to PDCCH repetition transmission from a UE. Here, the possible UE capability report may be at least one of a PDCCH repeated transmission method supported by the UE (for example, may be one of methods 1-1 to 1-5), and a UE capability reporting method related to soft combining (whether soft combining is possible, a possible level of soft combining, a limitation required for soft combining, etc.) considered in the second embodiment, or a part thereof. In another embodiment, operation 1800 may be omitted when information about UE capabilities is preconfigured for the respective UE. In addition, when information on UE capabilities is equally applied to a predetermined group of UEs as default information, operation 1800 may be omitted.
Thereafter, in operation 1801, the base station may transmit first configuration information for PDCCH to the UE, and in operation 1802, may further perform transmission of second configuration information for PDCCH repetition transmission. Here, the second configuration information may include information about at least one of: repeated transmission method, number of repeated transmissions, repeated transmission interval, repeated transmission period, PDCCH monitoring opportunity assuming repeated transmission, whether link or association between repeated transmissions can be checked, and information on control resource set+search space configured with repeated transmission. In addition, the base station may also perform transmission of third configuration information in operation 1803. Here, the third configuration information may include information on at least one of an aggregation level, a PDCCH candidate set, and frequency resources, or may not configure any one thereof according to the method of the third embodiment. In addition, the base station may transmit at least a portion of the first to third configuration information through L1 signaling, or may implicitly determine at least a portion thereof based on other configuration information. In addition, the first to third configuration information may be included in one configuration information and provided to the UE.
After transmitting the configuration information, the base station recognizes that transmission is performed using a plurality of control resource sets + search spaces configured with repeated transmission in operation 1804, and if the base station transmits a PDCCH using a control resource set and/or a search space other than the control resource set + search space configured with repeated transmission, the process proceeds to operation 1806, and the base station may operate based on a single PDCCH transmission as an existing PDCCH transmission operation (second transmission operation). Meanwhile, if the base station transmits the PDCCH using the control resource set+search space configured with repeated transmission in operation 1804, the process proceeds to operation 1805, and the base station may perform a first transmission operation in operation 1805. The first transmit operation may be understood as: the UE may determine that repeated transmission of the PDCCH is performed by the base station according to the configuration information and using a single PDCCH receiving method as an existing PDCCH receiving operation, or may assume that soft combining is performed between candidate PDCCHs that are assumed to be capable of soft combining and are explicitly connected to each other, and the base station performs PDCCH repeated transmission to the UE.
< fifth embodiment: method of operation of base station and UE when multiple different PDCCH candidates overlap >
As an embodiment of the present disclosure, a detailed method of operation of a base station and a UE when a plurality of different PDCCH candidates overlap will be described. In the following (5-1) embodiment, the operations of the base station and the UE in the case where a plurality of different PDCCH candidates for a single transmission overlap are described, and in the (5-2) embodiment, the operations of the base station and the UE in the case where a PDCCH candidate for a single transmission and two PDCCH candidates for a repeated transmission overlap are described.
< embodiment (5-1): case where multiple different candidate PDCCHs for a single transmission overlap >
In case that the first PDCCH candidate in the nth search space and the second PDCCH candidate in the mth search space are transmitted at the same CCE location, the same scrambling code (e.g., a specific RNTI) is used and DCI bit sizes of the same length, wherein both the nth search space and the mth search space are connected to the same control resource set, the UE may not perform Blind Decoding (BD) counting on the first PDCCH candidate in the nth search space if n > m. For example, when the first PDCCH candidate and the second PDCCH candidate are not completely distinguished with respect to the UE, the UE may perform BD only once. In addition, in the above example, the UE may perform monitoring on the first PDCCH candidate and the second PDCCH candidate. Here, monitoring may be understood as descrambling PDCCH data obtained by performing BD, for example, through a specific RNTI. In the above case, the same scrambling code is used, and thus the UE may not know the search space from which the PDCCH candidates are derived.
In addition, in case that the nth and mth PDCCH candidates in the xth search space are transmitted at the same CCE location, the same scrambling code (e.g., specific RNTI) is used, DCI bit sizes having the same length, and are transmitted from the same control resource set, the UE may not perform BD counting on the nth PDCCH candidate if n < m. For example, when the nth candidate PDCCH and the mth candidate PDCCH are not completely distinguished with respect to the UE, the UE may perform BD only once. In addition, in the above example, the UE may perform monitoring on the nth and mth PDCCH candidates. Here, monitoring may be understood as descrambling PDCCH data obtained by performing BD, for example, through a specific RNTI. In the above case, the same scrambling code is used, and thus the UE may not know the search space from which the PDCCH candidates are derived.
< embodiment (5-2): case where two candidate PDCCHs for a single transmission overlap with each other
According to an embodiment of the present disclosure, an operation of a base station and a UE in the case where a candidate PDCCH for a single transmission and two candidate PDCCHs for repeated transmission overlap will be described. In this embodiment, at least two cases can be considered as follows. The operation of the base station and the UE in each case will be described in detail.
Case 5-2-1 case where one of two candidate PDCCHs for repeated transmission overlaps with one candidate PDCCH for single transmission
This situation may take into account the following: the a-th and b-th search spaces are linked to each other through higher layer signaling to perform PDCCH retransmission and perform PDCCH retransmission, and thus the first and second PDCCH candidates are transmitted in the a-th and b-th search spaces, respectively; both the a-th and b-th search spaces are connected to the same set of control resources (e.g., a first set of control resources) or to different sets of control resources (e.g., the a-th search space is connected to the first set of control resources and the b-th search space is connected to a second set of control resources); and a c-th search space for a single PDCCH transmission is connected to the first set of control resources and transmits a third PDCCH candidate. Here, if the first PDCCH candidates transmitted in the first control resource set connected to the a-th search space and the third PDCCH candidates transmitted in the same first control resource set connected to the c-th search space are transmitted at the same CCE location, DCI bit sizes having the same length and transmitted in the same control resource set are used with the same scrambling code (e.g., a specific RNTI), the UE may not perform BD counting on the third PDCCH candidates for single transmission. That is, when the first PDCCH candidate and the third PDCCH candidate are not completely distinguished with respect to the UE, the UE may perform the same number of BD counts as the number of BD counts consumed for transmission of the two PDCCHs for repeated transmission, for the two PDCCHs for repeated transmission and one PDCCH candidate for single transmission. Here, the number of BD counts consumed for two PDCCH transmissions for repeated transmissions may be reported as UE capability, and its value may be, for example, 2 or 3. If the UE does not report to the base station the UE capability related to the BD count number, the base station may assume, for example, 2 or 3 as a default value for the BD count number consumed for repeated transmission of two candidate PDCCHs for the corresponding UE. If the UE interprets information of the PDCCH that has been successfully decoded, the UE may perform interpretation based on a reference candidate PDCCH considered during PDCCH repetition transmission (e.g., when scheduling of PDSCH or aperiodic CSI-RS is performed, the UE may perform scheduling based on a candidate PDCCH having a later start time among two repeated candidate PDCCHs).
Regarding the above, it may be determined whether to perform monitoring on the third PDCCH candidate for a single transmission, considering the following method.
Regardless of the specific conditions, the UE may perform monitoring on the third PDCCH candidate for a single transmission. Here, the specific condition may refer to a condition in consideration of: the number of BD counts consumed for the two PDCCH candidates for repeated transmission as a UE capability report, whether the a-th to c-th search spaces are configured as a common search space or a UE-specific search space, and the number of control resource sets connected to the a-th and b-th search spaces via a higher layer signaling connection.
The UE may not perform monitoring of the third PDCCH candidate for a single transmission, regardless of the specific conditions. Here, the specific condition may refer to a condition in consideration of: the number of BD counts consumed for the two PDCCH candidates for repeated transmission as a UE capability report, whether the a-th to c-th search spaces are configured as a common search space or a UE-specific search space, and the number of control resource sets connected to the a-th and b-th search spaces via a higher layer signaling connection.
The UE may determine whether to perform monitoring on the third PDCCH candidate for a single transmission according to the number of BD counts consumed by the two PDCCH candidates for repeated transmission as a UE capability report. If the number of BD counts consumed for two PDCCH candidates for repeated transmission as a UE capability report is 3, the UE may perform monitoring on a third PDCCH candidate for a single transmission. Alternatively, if the number of BD counts consumed for two candidate PDCCHs for repeated transmission as a UE capability report is 2, the UE may not perform monitoring on the third candidate PDCCH for a single transmission.
The UE may determine whether to perform monitoring on the third PDCCH candidate for a single transmission according to the number of BD counts consumed by the two PDCCH candidates for repeated transmission as a UE capability report. If the number of BD counts consumed for two PDCCH candidates for repeated transmission as a UE capability report is 3, the UE may not perform monitoring on the third PDCCH candidate for single transmission. Alternatively, if the number of BD counts consumed for two PDCCH candidates for repeated transmission as a UE capability report is 2, the UE may perform monitoring on a third PDCCH candidate for single transmission.
-the UE may perform monitoring on a third PDCCH candidate for a single transmission when the number of BD counts consumed for two PDCCH candidates for repeated transmission as a UE capability report is 3. Alternatively, when the number of BD counts consumed for two candidate PDCCHs for repeated transmission as a UE capability report is 2, the UE may report whether to perform monitoring on a third candidate PDCCH for a single transmission as an additional UE capability. Here, the value reported as the additional UE capability may indicate whether monitoring is being performed, and if the additional UE capability is not reported, the base station may consider that the UE may not perform monitoring on the third candidate PDCCH as a default value. In addition, the value reported as the additional UE capability may indicate that monitoring is being performed, and if the additional UE capability is not reported, the base station may consider that the UE does not perform monitoring on the third candidate PDCCH as a default value.
-the UE may perform monitoring on a third PDCCH candidate for a single transmission when the number of BD counts consumed for two PDCCH candidates for repeated transmission as a UE capability report is 3. Alternatively, when the number of BD counts consumed for two candidate PDCCHs for repeated transmission as a UE capability report is 2, and according to whether the above-described a-th to c-th search spaces are configured as UE-specific search spaces or common search spaces, the UE may report whether to perform monitoring on a third candidate PDCCH for a single transmission as additional UE capability. Here, the value reported as the additional UE capability may indicate whether monitoring is being performed, and if the additional UE capability is not reported, the base station may consider that the UE may perform monitoring on the third candidate PDCCH as a default value, or may consider that the UE may not perform monitoring. In addition, the value reported as the additional UE capability may indicate that monitoring is being performed, and if the additional UE capability is not reported, the base station may consider that the UE does not perform monitoring on the third candidate PDCCH as a default value. In addition, in case that the number of BD counts consumed for two candidate PDCCHs for repeated transmission as a UE capability report is 2 and the c-th search space is a common search space, if the UE does not report to the base station whether to monitor the third candidate PDCCH for single transmission, the base station may consider that the UE performs monitoring on the third candidate PDCCH as a default value as an additional terminal capability. In addition, in the case where the number of BD counts consumed for two candidate PDCCHs for repeated transmission as a UE capability report is 2 and the c-th search space is a common search space, if the UE does not report to the base station whether to monitor the third candidate PDCCH for single transmission, the base station may consider that the UE does not perform monitoring on the third candidate PDCCH as a default value as an additional terminal capability.
The UE may report to the base station whether monitoring is performed on the third PDCCH candidate for a single transmission as an additional UE capability according to certain conditions. Here, the specific condition may refer to the number of BD counts consumed for two candidate PDCCHs for repeated transmission as a UE capability report, whether the a-th to c-th search spaces are configured as UE-specific search spaces, the number of control resource sets connected with the a-th and b-th search spaces via a high layer signaling connection, and the number of search space pairs via a high layer signaling connection.
■ As an example, whether to perform monitoring on the third PDCCH candidate for a single transmission may be reported as additional UE capability according to the number of BD counts consumed by the two PDCCH candidates for repeated transmissions as UE capability reports. Here, the value reported as the additional UE capability may indicate whether monitoring is being performed, and in the case where the additional UE capability is not reported, if the number of BD counts consumed for two candidate PDCCHs for repeated transmission reported as the UE capability is 3 or 2, the base station may consider that the UE does not perform monitoring on the third candidate PDCCH as a default item in both cases. Based on the case that the number of BD counts consumed for two PDCCH candidates for repeated transmission as a UE capability report is 3 and 2, the base station may consider that the UE has performed monitoring on the third PDCCH candidate or has not performed monitoring on the third PDCCH candidate as a default item, respectively. Based on the case that the number of BD counts consumed for two PDCCH candidates for repeated transmission as a UE capability report is 3 and 2, the base station may consider that the UE does not perform monitoring on the third PDCCH candidate and the UE performs monitoring on the third PDCCH candidate as default items, respectively. If the number of BD counts consumed for two PDCCH candidates for repeated transmission as a UE capability report is 3 and 2, the base station may consider that the UE performs monitoring on the third PDCCH candidate as a default item.
■ As an example, whether to perform monitoring on the third candidate PDCCH for a single transmission may be reported as an additional UE capability, depending on whether the a-th to c-th search spaces are configured as a common search space or a UE-specific search space. Here, the value reported as additional UE capabilities may indicate whether monitoring is being performed. Here, the UE may report a total of four types of values according to the following case: 1) The a-th search space and the b-th search space are UE-specific search spaces, and the c-th search space is a common search space; 2) The a-th search space and the b-th search space are common search spaces, and the c-th search space is a UE-specific search space; 3) All of the a-th search space to the c-th search space are common search spaces; 4) All of the a-th to c-th search spaces are UE-specific search spaces, and the UE may report values only in some of these cases. If additional UE capability is not reported, the base station may consider as a default one of the case where the UE performs monitoring on the third PDCCH candidate and the case where the UE does not perform monitoring on the third PDCCH candidate, each of the above four cases. For example, regarding two cases where the c-th search space is a common search space, if additional UE capabilities are not reported, the base station may consider the UE to perform monitoring on the third PDCCH candidate for a single transmission.
■ As an example, when the UE reports whether to perform monitoring on the third PDCCH candidate for single transmission as additional UE capability, the UE may report the additional UE capability to the base station by considering the number of BD counts consumed by the two PDCCH candidates for repeated transmission as UE capability reports, and whether the above-described a-th to c-th search spaces are configured as a common search space or a UE-specific search space. For example, in case that the UE has reported that the number of BD counts consumed for two candidate PDCCHs for repeated transmission is 2, the a-th search space and the b-th search space are UE-specific search spaces, and the c-th search space is a common search space, the UE may report to the base station that monitoring is performed on the third candidate PDCCH as an additional UE capability. In addition, in the above example, when the UE does not report additional UE capabilities, the base station may consider that the UE does not perform monitoring on the third PDCCH candidate as a default value. Alternatively, for another combination (e.g., the number of BD counts consumed by two candidate PDCCHs for repeated transmission by different UEs, and whether the a-th to c-th search spaces are configured as a combination of UE-specific search spaces or common search spaces), it may be reported separately as additional UE capabilities, and if the additional UE capabilities of each combination are not reported, the base station may consider it to be one of the case where the UE performs monitoring on the third candidate PDCCH and the case where the UE does not perform monitoring on the third candidate PDCCH.
Case 5-2-2 when one of two candidate PDCCHs for repeated transmission overlaps one candidate PDCCH for single transmission and the other of the two candidate PDCCHs for repeated transmission overlaps one candidate PDCCH for single transmission.
This situation may take into account the following: the a-th and b-th search spaces are linked to each other via higher layer signaling for PDCCH retransmission and PDCCH retransmission is performed such that the first and second PDCCH candidates are transmitted in the a-th and b-th search spaces, respectively; both the a-th and b-th search spaces are connected to the same set of control resources (e.g., a first set of control resources) or to different sets of control resources (e.g., the a-th search space is connected to the first set of control resources and the b-th search space is connected to a second set of control resources); a c-th search space for single PDCCH transmission is connected to the first set of control resources and transmits a third PDCCH candidate; and the d-th search space is connected to the first control resource set (or the second control resource set when the above-mentioned b-th search space is connected to the second control resource set) and transmits the fourth PDCCH candidate. Here, if the first PDCCH candidates transmitted in the first control resource set connected to the a-th search space and the third PDCCH candidates transmitted in the same first control resource set connected to the c-th search space are transmitted at the same CCE location, DCI bit sizes having the same length and transmitted in the same control resource set are used with the same scrambling code (e.g., a specific RNTI), the UE does not perform BD counting on the third PDCCH candidates for single transmission. Meanwhile, if a second PDCCH candidate transmitted in a first control resource set (or a second control resource set) connected to a b-th search space and a fourth PDCCH candidate transmitted in the same first control resource set (or second control resource set) connected to a d-th search space are transmitted at the same CCE location, DCI bit sizes having the same length and transmitted in the same control resource set are used with the same scrambling code (e.g., a specific RNTI), the UE does not perform BD counting on the third PDCCH candidate, and the third PDCCH candidate is for single transmission. That is, when the first and third candidate PDCCHs and the second and fourth candidate PDCCHs are not completely distinguished with respect to the UE, for the two candidate PDCCHs for repeated transmission and the two candidate PDCCHs for single transmission, the same BD count as the number of BD counts consumed for the two candidate PDCCHs for repeated transmission may be performed. Here, the number of BD counts consumed for two PDCCH transmissions for repeated transmissions may be reported as UE capability, and its value may be, for example, 2 or 3. If the UE does not report UE capability related to the BD count number to the base station, the base station may assume 2 or 3 as a base value for the BD count number consumed by the two candidate PDCCHs for repeated transmission by the corresponding UE.
This case takes into account the following: the first PDCCH candidate, which is one of the two PDCCH candidates for repeated transmission, overlaps with the third PDCCH candidate for single transmission, while the second PDCCH candidate, which is one of the two PDCCH candidates for repeated transmission, overlaps with the fourth PDCCH candidate for single transmission. Here, if the UE may perform separate decoding at the positions of two overlapping candidate PDCCHs in order to obtain information indicating that decoded PDCCHs are identical or different from each other, and when interpreting information in PDCCHs that have been successfully decoded, if the two decoded PDCCHs are identical, information interpretation may be performed based on a reference candidate PDCCH considered during PDCCH repetition transmission (for example, when scheduling of PDSCH or aperiodic CSI-RS is performed, scheduling may be performed based on a candidate PDCCH having a later start time among the two repeated candidate PDCCHs). If the two PDCCHs are different, information in the PDCCH can be interpreted based on each PDCCH for a single transmission. If the UE cannot perform separate decoding on the positions of the two overlapping PDCCH candidates or can perform separate decoding only on a portion thereof, or if it is impossible to check whether the two overlapping PDCCH candidates are identical, the UE may perform interpretation based on the reference PDCCH candidates considered during the PDCCH repetition transmission.
For the above case, regarding whether to perform monitoring on the third PDCCH candidate for a single transmission, the method considered in [ case 5-2-1] may be similarly considered. In addition, the UE may determine whether to perform monitoring on the third and fourth PDCCH candidates by considering whether the time position where the first and third PDCCH candidates overlap is the same or different from the time position where the second and fourth PDCCH candidates overlap, or may report whether to perform monitoring as an additional UE capability by the above-described various methods. Here, it may be determined whether to differently perform monitoring on the third candidate PDCCH and the fourth candidate PDCCH, and whether to differently perform monitoring may be reported as an additional UE capability.
The PDCCH candidates considered in the above [ case 5-2-1] and [ case 5-2-2] overlap for single transmission and for repeated transmission, are transmitted at the same CCE location, use the same scrambling code (e.g., specific RNTI), have the DCI bit size of the same length, and in case of the same control resource set transmission, the UE may report at least one of the following to the base station: whether to allow overlap between PDCCH candidates as an additional UE capability, and the number of overlapping PDCCH candidates allowed within a specific time resource (per OFDM symbol, per monitoring occasion, per slot, or per span) when allowed. In conjunction with each of [ case 5-2-1] and [ case 5-2-2], the UE may report the maximum number of overlaps of PDCCH candidates allowed within a particular time resource by adding UE capabilities. Additional UE capabilities may be reported for each individual cell and may be reported for all cells. When reporting is performed for each individual cell, additional UE capability reporting may be performed for each parameter set by considering the parameter set of each cell; and when reporting is performed for all cells, additional UE capabilities may be reported based on the minimum parameter set or the maximum parameter set. Here, the reported value may be 0, and the UE having reported "0" may be understood as not allowing [ case 5-2-1] or [ case 5-2-2]. In addition, regarding additional UE capabilities, information of each type combination of a search space for transmitting a repetition candidate PDCCH and a search space for transmitting a single transmission candidate PDCCH may be reported separately. For example, in the case of [ case 5-2-1], for < search space 1, search space 2>, there may be a total of four types (i.e., < common, common >, < common, UE-specific >, < UE-specific, common >, < UE-specific, UE-specific >), and search spaces 1 and 2 may correspond to repeated transmissions and a single transmission, respectively. In the case of [ case 5-2-2], there may be a total of eight types (i.e., < public, public >, < public, UE-specific >, < public, UE-specific, public >, < public, UE-specific, UE-specific >, < UE-specific, common >, < UE-specific, common, UE-specific >, < UE-specific, common >, < UE-specific, UE-specific >), and search spaces 1, 2, and 3 correspond to repeated transmissions, single transmission 1, and single transmission 2, respectively.
Meanwhile, each of the configurations or operations may be selectively combined/combined and applied among the above-described embodiments and methods of the present disclosure, and each of the examples is for technical convenience, and the scope of the present disclosure is not limited thereto.
Fig. 19 illustrates a structure of a UE in a wireless communication system according to an embodiment of the present disclosure.
Referring to fig. 19, the UE may include a transceiver, a memory (not shown), and a UE processor 19-05 (or UE controller or processor) involving a UE receiver 19-00 and a UE transmitter 19-10. The transceivers 19-00 and 19-10, the memory and the UE processor 19-05 of the UE may operate according to the communication methods of the UE described above. However, elements of the UE are not limited to the above examples. For example, the UE may include more or fewer elements than those described above. In addition, the transceiver, memory and processor may be implemented in the form of one chip.
The transceiver may transmit signals to/receive signals from the base station. Here, the signal may include control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low noise amplifying and down-converting the received signal. However, this is merely an exemplary embodiment of a transceiver, and elements of a transceiver are not limited to RF transmitters and RF receivers.
In addition, the transceiver may receive signals through a wireless channel and output the received signals to the processor, and may transmit signals output from the processor through the wireless channel.
The memory may store programs and data necessary for the operation of the UE. In addition, the memory may store control information or data included in signals transmitted and received by the UE. The memory may be configured as a storage medium or combination of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. In addition, there may be multiple memories.
In addition, the processor may control a series of processes so that the UE may operate according to the above-described embodiments. For example, the processor may receive DCI including two layers, and an element controlling the UE receives multiple PDSCH simultaneously. There may be a plurality of processors, and the processors may perform operations of controlling the UE elements by executing programs stored in the memory.
Fig. 20 illustrates a structure of a base station in a wireless communication system according to an embodiment of the present disclosure.
Referring to fig. 20, a base station may include transceivers, memory (not shown), and a base station processor 20-05 (or a base station controller or processor) involving a base station receiver 20-00 and a base station transmitter 20-10. The transceivers 20-00 and 20-10, the memory, and the base station processor 20-05 of the base station may operate according to the communication methods of the base station described above. However, elements of the base station are not limited to the above examples. For example, a base station may include more or fewer elements than those described above. In addition, the transceiver, memory and processor may be implemented in the form of one chip.
The transceiver may transmit/receive signals to/from the UE. Here, the signal may include control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low noise amplifying and down-converting the received signal. However, this is merely an exemplary embodiment of a transceiver, and elements of a transceiver are not limited to RF transmitters and RF receivers.
In addition, the transceiver may receive signals through a wireless channel and output the received signals to the processor, and may transmit signals output from the processor through the wireless channel.
The memory may store programs and data necessary for operation of the base station. In addition, the memory may store control information or data included in signals transmitted and received by the base station. The memory may be configured as a storage medium or combination of storage media such as ROM, RAM, hard disk, CD-ROM, and DVD. In addition, there may be multiple memories.
The processor may control a series of processes so that the base station may operate according to the above-described embodiments. For example, the processor may configure layers of two types of DCI, the DCI including allocation information for a plurality of PDSCH, and may control each element of the base station to transmit the DCI. There may be a plurality of processors, and the processors may perform the operations of controlling the base station elements by executing programs stored in the memory.
The methods according to the embodiments described in the claims or the present disclosure may be implemented by hardware, software, or a combination of hardware and software.
When the method is implemented by software, a computer readable storage medium for storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured to be executed by one or more processors within the electronic device. At least one program may comprise instructions that cause an electronic device to perform a method according to various embodiments of the present disclosure as defined by the appended claims and/or disclosed herein.
Programs (software modules or software) may be stored in non-volatile memory including random access memory and flash memory, read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), magnetic disk storage, compact disc ROM (CD-ROM), digital Versatile Disks (DVD), or other types of optical storage or magnetic tape. Alternatively, any combination of some or all of them may form a memory in which the program is stored. In addition, a plurality of such memories may be included in the electronic device.
In addition, the program may be stored in an attachable storage device that can access the electronic device through a communication network such as the internet, an intranet, a Local Area Network (LAN), a Wide LAN (WLAN), and a Storage Area Network (SAN), or a combination thereof. Such storage devices may access the electronic device via an external port. In addition, a separate storage device on the communication network may access the portable electronic device.
In the above detailed embodiments of the present disclosure, elements included in the present disclosure are expressed as singular or plural according to the presented detailed embodiments. However, for convenience of description, a singular form or a plural form is appropriately selected for the presented case, and the present disclosure is not limited to the elements expressed in the singular or the plural. Accordingly, elements expressed in plural may also include a single element, or elements expressed in singular may also include a plurality of elements.
The embodiments of the present disclosure described in the specification and shown in the drawings are merely specific embodiments presented for ease of explaining the technical content of the present disclosure and to aid in understanding the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it is apparent to those skilled in the art that other variations based on the technical ideas of the present disclosure may be implemented. In addition, the respective embodiments described above may be used in combination as necessary. For example, one embodiment of the present disclosure may be combined in part with another embodiment to operate a base station and a terminal. As an example, embodiments 1 and 2 of the present disclosure may be partially combined to operate a base station and a terminal. In addition, although the above embodiments have been described by an FDD LTE system, other variations in implementation-based techniques may be implemented in other systems, such as TDD LTE and 5G or NR systems.
In the drawings describing the methods of the present disclosure, the order of description does not necessarily always correspond to the order of steps of performing each method, and the sequential relationship between the steps may be changed or the steps may be performed in parallel.
Alternatively, in the drawings describing the method of the present disclosure, some elements may be omitted, and only some elements may be included, without departing from the true spirit and scope of the present disclosure.
Additionally, in the methods of the present disclosure, some or all of the contents of each embodiment may be implemented in combination without departing from the present disclosure.
Various embodiments of the present disclosure have been described. The foregoing description of the present disclosure is for illustrative purposes only and is not intended to limit the disclosed embodiments to the embodiments set forth herein. It will be understood by those skilled in the art that other specific modifications and changes can be readily made to the present disclosure without changing the technical spirit or essential features of the present disclosure. The scope of the present disclosure should be determined not by the above description but by the appended claims, and all changes and modifications that come within the meaning and range of the claims and their equivalents should be construed to be within the scope of the present disclosure.
While the present disclosure has been described with various embodiments, various changes and modifications may be suggested to one skilled in the art. The disclosure is intended to embrace such alterations and modifications that fall within the scope of the appended claims.
Claims (15)
1. A method performed by a terminal in a wireless communication system, the method comprising:
receiving configuration information for Physical Downlink Control Channel (PDCCH) monitoring;
identifying, based on the configuration information, a monitoring opportunity related to a first PDCCH candidate and a second PDCCH candidate for first downlink control information, DCI, format detection, and a monitoring opportunity related to a third PDCCH candidate for second DCI format detection; and
the PDCCH monitoring is performed based on the identifying,
wherein, in case that one of the first and second PDCCH candidates overlaps with the third PDCCH candidate, the third PDCCH candidate is not counted to a blind decoding number.
2. The method of claim 1, wherein the configuration information comprises information indicating that a first search space associated with the first PDCCH candidate and a second search space associated with the second PDCCH candidate are linked for repeated PDCCH transmissions.
3. The method of claim 1, wherein the second DCI format has a same size as the first DCI format, and
wherein one of the first PDCCH candidate and the second PDCCH candidate overlapping the third PDCCH candidate and the third PDCCH are associated with the same scrambling code, the same set of control channel elements CCEs, and the same set of control resources CORESET.
4. The method of claim 1, further comprising transmitting first capability information indicating the number of blind decodes counted for monitoring candidate PDCCHs for repeated PDCCH transmission,
wherein the first capability information indicates 2 or 3.
5. The method of claim 1, further comprising transmitting second capability information indicating whether the terminal monitors a single PDCCH candidate,
and monitoring the third PDCCH candidate under the condition that the second capability information indicates that the terminal monitors the single PDCCH candidate.
6. The method of claim 1, further comprising transmitting third capability information indicating a maximum amount of overlap between one of the PDCCH candidates for repeated PDCCH transmissions and a single PDCCH candidate.
7. The method of claim 1, further comprising determining a detected DCI format as the first DCI format.
8. A terminal in a wireless communication system, the terminal comprising:
a transceiver; and
a controller configured to:
configuration information for physical downlink control channel PDCCH monitoring is received via the transceiver,
identifying, based on the configuration information, a monitoring opportunity related to a first candidate PDCCH and a second candidate PDCCH for first downlink control information DCI format detection, and a monitoring opportunity related to a third candidate PDCCH for second DCI format detection, and
the PDCCH monitoring is performed based on the identifying,
wherein, in case that one of the first and second PDCCH candidates overlaps with the third PDCCH candidate, the third PDCCH candidate is not counted to a blind decoding number.
9. The terminal of claim 8, wherein the configuration information includes information indicating that a first search space associated with the first PDCCH candidate and a second search space associated with the second PDCCH candidate are linked for repeated PDCCH transmissions.
10. The terminal of claim 8, wherein the second DCI format has a same size as the first DCI format.
11. The terminal of claim 8, wherein one of the first PDCCH candidate and the second PDCCH candidate overlapping the third PDCCH candidate and the third PDCCH are associated with a same scrambling code, a same set of control channel element CCEs, and a same set of control resources CORESET.
12. The terminal of claim 8, wherein the controller is further configured to transmit, via the transceiver, first capability information indicating the number of blind decodes counted for monitoring candidate PDCCHs for repeated PDCCH transmission, and
wherein the first capability information indicates 2 or 3.
13. The terminal of claim 8, wherein the controller is further configured to transmit second capability information via the transceiver, the second capability information indicating whether the terminal monitors a single PDCCH candidate, and
and monitoring the third PDCCH candidate under the condition that the second capability information indicates that the terminal monitors the single PDCCH candidate.
14. The terminal of claim 8, wherein the controller is further configured to transmit third capability information via the transceiver, the third capability information indicating a maximum amount of overlap between one of the PDCCH candidates for repeated PDCCH transmission and a single PDCCH candidate.
15. The terminal of claim 8, wherein the controller is further configured to determine the detected DCI format as the first DCI format.
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| KR10-2021-0006333 | 2021-01-15 | ||
| KR10-2021-0011826 | 2021-01-27 | ||
| KR1020210114198A KR20220103610A (en) | 2021-01-15 | 2021-08-27 | Method and apparatus for configuration of repetitive transmission and reception for downlink control information in a wireless communication system |
| KR10-2021-0114198 | 2021-08-27 | ||
| PCT/KR2022/000744 WO2022154582A1 (en) | 2021-01-15 | 2022-01-14 | Method and apparatus for configuration of repetitive transmission and reception of downlink control information in wireless communication system |
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