Method and apparatus for downlink OFDMA with DFT precoding

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates than a 4G communication system (such as LTE). According to an embodiment, a method of a base station in a communication system may include: determining the number of DFT precoding blocks on which DFT precoding is performed; determining a power backoff value of a power amplifier (PA) of the base station; sending information indicating the number of DFT precoding blocks to a terminal; sending downlink control information (DCI) to the terminal, the DCI including a resource allocation field configured according to the number of precoding blocks; and sending data to the terminal according to the resource allocation field included in the DCI.

Description

Technical Field

[0001] The present disclosure relates to methods and apparatus using downlink OFDMA with DFT precoding applied. Background Art

[0002] Generation after generation of wireless communication development has been committed to service technologies for humans (e.g., voice communication, multimedia, and data services). It is expected that after the commercialization of the fifth generation (5G) communication system, networked devices will increase exponentially and be connected to the communication network. Examples of things connected to the network include, for example, vehicles, robots, drones, home appliances, displays, smart sensors installed in various infrastructures, construction machinery, and factory equipment. Mobile devices are expected to develop into various form factors, such as augmented reality glasses, virtual reality head-mounted devices, and holographic devices. In the sixth generation (6G) era, efforts have been made to develop improved 6G communication systems to provide various services by connecting billions of devices and things. Therefore, 6G communication systems are also called super 5G systems.

[0003] The 6G communication system, which is expected to be implemented around 2030, will have a maximum transmission rate of multiples of Tera bps (1,000 giga bps) and a radio latency of 100 μsec. This means that the transmission rate of the 6G communication system is 50 times that of the 5G communication system, while the radio latency is 1 / 10 of that of the 5G communication system.

[0004] To achieve such high data rates and ultra-low latency, 6G communication systems are being considered in the terahertz band (e.g., 95 GHz to 3 THz). Since path loss is more severe and absorption in the atmosphere is more severe than in the millimeter wave band introduced by 5G, it is expected that technologies that can guarantee coverage (the distance the signal reaches) will become more important in the terahertz band. The main technologies being developed to ensure coverage include technologies that outperform radio frequency (RF) components, antennas, and orthogonal frequency division multiplexing (OFDM) in terms of coverage, such as new waveforms, beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), and multi-antenna transmission technologies (e.g., array antennas and massive antennas). Furthermore, new technologies to improve the coverage of terahertz band signals, such as metamaterial-based lenses and antennas, high-dimensional spatial multiplexing technologies utilizing orbital angular momentum (OAM), and reconfigurable smart surfaces (RIS), are currently under discussion.

[0005] Furthermore, to improve frequency efficiency and system networks, the following technologies related to 6G communication systems are currently being developed: full-duplex technology, which allows both uplink and downlink to utilize the same frequency resources simultaneously; network technologies that integrate satellites and high-altitude platform stations (HAPS); innovative network architecture technologies that support mobile base stations and achieve optimized and automated network operations; dynamic spectrum sharing technologies that avoid collisions based on spectrum usage predictions; AI-based communication technologies that leverage artificial intelligence (AI) from the design stage and embed end-to-end AI support functions to achieve system optimization; and next-generation distributed computing technologies that enable services at a level of complexity exceeding the computing capabilities of devices by utilizing ultra-high-performance communication and computing resources (e.g., mobile edge computing (MEC) and the cloud). Furthermore, efforts are underway to design new protocols for use in 6G communication systems, implement hardware-based security environments, develop mechanisms for secure data utilization, and develop technologies for privacy protection methods. These efforts aim to further strengthen connectivity between devices, further optimize networks, promote the trend toward software-based network implementation, and increase the openness of wireless communications.

[0006] This research and development of 6G communication systems is expected to enable the next hyperconnected experience through the hyperconnectivity of 6G communication systems, encompassing not only connections between things but also between people and things. Specifically, it is predicted that 6G communication systems will enable services such as truly immersive extended reality (XR), high-fidelity mobile holograms, and digital replicas. Furthermore, due to improved security and reliability, services such as remote surgery, industrial automation, and emergency response will be provided through 6G communication systems, with applications in various fields such as industry, healthcare, automobiles, and home appliances.

[0007] Meanwhile, research is currently underway on methods of improving the efficiency of a power amplifier (PA) of a base station or a terminal operating in the above-mentioned communication system.

[0008] The above information is provided as background information only to assist in understanding the present disclosure. No judgment or conclusion is made as to whether any of the above content is applicable as prior art to the present disclosure. Summary of the Invention

[0009] Technical issues

[0010] Power amplifier (PA) efficiency may decrease in ultra-high frequency bands, such as the terahertz band (e.g., 95 GHz to 3 THz) considered in 6G communication systems. Generally speaking, the PA's power back-off increases proportionally with the peak-to-average power ratio (PAPR) of the input signal, and the PA's output efficiency decreases accordingly. Therefore, a technology is needed to reduce or appropriately adjust the PAPR of the signal to improve the efficiency of PAs in ultra-high frequency bands.

[0011] Solution to the problem

[0012] According to an embodiment, a method of a base station in a communication system may include: determining the number of DFT precoding blocks associated with the number of terminals performing frequency division multiplexing (FDM); determining a power backoff value of a power amplifier (PA) of the base station; sending information indicating the number of the DFT precoding blocks to the terminal; sending downlink control information (DCI) to the terminal, the DCI including a resource allocation field configured according to the number of the precoding blocks; and sending data to the terminal according to the resource allocation field included in the DCI.

[0013] According to an embodiment, the number of the DFT precoding blocks may be associated with a power back-off value of a power amplifier of the base station.

[0014] According to an embodiment, information indicating the number of DFT precoding blocks may be transmitted to the terminal through at least one of system information, radio resource control (RRC) signaling, and downlink control information (DCI).

[0015] According to an embodiment, the method may further include determining sizes of a determined number of DFT precoding blocks, and the resource allocation field may be configured based on the determined sizes of the DFT precoding blocks.

[0016] According to an embodiment, the DCI may include information related to the size of the DFT precoding block.

[0017] In addition, a method of a terminal in a communication system according to an embodiment may include: receiving information indicating the number of DFT precoding blocks on which DFT precoding is performed from a base station; receiving downlink control information (DCI) from the base station, the DCI including a resource allocation field configured based on the number of DFT precoding blocks; and receiving data from the base station according to the resource allocation field included in the DCI.

[0018] In addition, a base station in a communication system according to an embodiment may include a transceiver and a controller, wherein the controller is configured to: determine the number of DFT precoding blocks on which DFT precoding is performed; determine a power backoff value of a power amplifier (PA) of the base station; send information indicating the number of DFT precoding blocks to a terminal; send downlink control information (DCI) to the terminal, the DCI including a resource allocation field configured based on the number of precoding blocks; and send data to the terminal according to the resource allocation field included in the DCI.

[0019] In addition, according to an embodiment, a terminal in a communication system may include: a transceiver and a controller, wherein the controller is configured to receive information indicating the number of DFT precoding blocks on which DFT precoding is performed from a base station; receive downlink control information (DCI) from the base station, the DCI including a resource allocation field configured based on the number of DFT precoding blocks; and receive data from the base station according to the resource allocation field included in the DCI.

[0020] Beneficial effects of the present invention

[0021] The base station can determine the amount and size of DFT precoding based on the trade-off between appropriate coverage and multi-user diversity gain required by a given communication environment, and can adjust the PA power backoff accordingly, thereby appropriately adjusting the PA output power. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts.

[0023] Figure 1 The time-frequency domain structure of the LTE communication system according to the embodiment of the present disclosure is described;

[0024] Figure 2 A downlink control channel of an LTE communication system according to an embodiment of the present disclosure is described;

[0025] Figure 3 The basic unit of a downlink control channel in a 5G communication system according to an embodiment of the present disclosure is described;

[0026] Figure 4 A control resource set (CORESET) through which a downlink control channel is transmitted in a 5G communication system according to an embodiment of the present disclosure is described;

[0027] Figure 5 An example of a resource block structure according to an embodiment of the present disclosure is illustrated;

[0028] Figure 6 The structure of a transmitter of a base station according to an embodiment of the present disclosure is described;

[0029] Figure 7 The structure of a digital transmitter of a base station according to an embodiment of the present disclosure is described;

[0030] Figure 8 The structure of a digital receiver of a UE according to an embodiment of the present disclosure is described;

[0031] FIG9A illustrates the operation of a base station according to an embodiment of the present disclosure;

[0032] FIG9B illustrates the operation of a UE according to an embodiment of the present disclosure;

[0033] Figure 10 An example of a PA power backoff value configured by a base station according to the number of DFT precoding blocks (K) according to an embodiment of the present disclosure is illustrated;

[0034] Figure 11 The present invention illustrates a case in which a base station transmits a determined K value as the number of DFT precoding blocks to a UE through a master information block (MIB) according to an embodiment of the present disclosure;

[0035] Figure 12 The present invention illustrates a case where a base station transmits a determined K value as the number of DFT precoding blocks to a UE through a system information block (SIB) according to an embodiment of the present disclosure;

[0036] Figure 13 A case in which a base station transmits a determined K value as the number of DFT precoding blocks to a UE through radio resource control (RRC) according to an embodiment of the present disclosure is described;

[0037] Figure 14 The present invention describes a case in which a base station transmits a determined K value as the number of DFT precoding blocks to a UE through downlink control information (DCI) according to an embodiment of the present disclosure;

[0038] Figure 15 The following describes a case where the sizes of K DFT precoding blocks are controlled to be the same according to an embodiment of the present disclosure.

[0039] Figure 16 The present invention describes a case where the sizes of K DFT precoding blocks are controlled to be different according to an embodiment of the present disclosure.

[0040] Figure 17 is a block diagram illustrating the structure of a base station according to an embodiment of the present disclosure;

[0041] Figure 18 is a block diagram illustrating the structure of a UE according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0042] Before proceeding with the detailed description below, it may be helpful to list the definitions of certain words and phrases used in this patent document. The terms "include" and "comprising," and their derivatives, mean to include without limitation; the term "or" is inclusive, meaning and / or; the phrases "associated with" and "associated with," and their derivatives, may mean to include, be included therein, be interconnected therewith, contain, be contained therein, be connected to or connected therewith, be coupled to or coupled therewith, cooperate with, interleave, be juxtaposed, be proximate, be coupled to or coupled therewith, have, have a certain attribute, etc. The term "controller" means any device, system, or portion thereof that controls at least one operation, which device may be implemented in hardware, firmware, or software, or some combination of at least two thereof. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely.

[0043] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed of 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, instruction sets, programs, functions, objects, classes, instances, related data or a portion thereof, suitable 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 that can be accessed by a computer, such as read-only memory (ROM), random access memory (RAM), hard drive, compact disc (CD), digital video disc (DVD), or any other type of memory. "Non-transitory" computer-readable media does not include wired, wireless, optical or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media that can permanently store data and media that can store data and be overwritten later, such as rewritable optical discs or erasable storage devices.

[0044] Definitions for certain words and phrases are provided in this patent document, which 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.

[0045] Discussed below Figures 1 to 18 The various embodiments used to describe the principles of the present disclosure in this patent document are intended to be illustrative only and should not be construed in any way to limit the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0046] Moving beyond the early stages of providing only voice services, wireless communication systems have evolved into broadband wireless communication systems that provide high-speed and high-quality packet data services, such as communication standards such as High Speed Packet Access (HSPA), Long Term Evolution (LTE or Evolved Universal Terrestrial Radio Access (E-UTRA)) and 3GPP's LTE-Advanced (LTE-A), 3GPP2's High Speed Packet Data (HRPD) and Ultra Mobile Broadband (UMB), IEEE 802.16e, and the like.

[0047] As a representative example of a broadband wireless communication system, the LTE system adopts an orthogonal frequency division multiplexing (OFDM) scheme in the downlink (DL) and a single carrier frequency multiple access (SC-FDMA) scheme in the uplink (UL). The uplink refers to the radio link through which a terminal (user equipment (UE)) or a mobile station (MS) sends data or control signals to a base station (eNode or BS). The downlink refers to the radio link through which a base station sends data or control signals to a terminal. In the multiple access scheme described above, the time-frequency resources for transmitting data or control information to each user are often allocated and managed so as to meet orthogonality, that is, they do not overlap with each other, so that the data or control information of each user can be distinguished.

[0048] Future communication systems following LTE, namely 5G communication systems, will need to freely adapt to various requirements from users, service providers, and others, and therefore need to support services that simultaneously meet these requirements. Services considered for 5G communication systems may include enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC).

[0049] eMBB aims to provide data transmission rates that are higher than those supported by conventional LTE, LTE-A, or LTE-pro. For example, in a 5G communication system, from the perspective of the eNB, eMBB needs to provide a maximum transmission rate (peak data rate) of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink. In addition, the 5G communication system needs to provide an enhanced user-perceived data rate for the UE while providing peak data rates. To meet these requirements, it is desirable to improve various transmission or reception technologies, including advanced multiple-input multiple-output (MIMO) transmission technology. In addition, current LTE uses a maximum transmission bandwidth of 20 MHz to transmit signals within the 2 GHz frequency band. However, the 5G communication system uses a frequency bandwidth wider than 20 MHz in the 3 to 6 GHz frequency band or in a frequency band greater than or equal to 6 GHz, thereby meeting the data transmission rates required by the 5G communication system.

[0050] 5G communication systems also incorporate mobile machine type communication (mMTC) to support application services such as the Internet of Things (IoT). mMTC requires supporting access to a large number of UEs within a cell, improving UE coverage, enhancing battery life, and reducing UE costs to effectively deliver the IoT. IoT provides communication capabilities by attaching to various sensors and devices. Therefore, a large number of UEs must be supported within a cell (e.g., 1,000,000 UEs per square kilometer). Furthermore, due to the nature of the services, mMTC-enabled UEs are likely to be located in shadowed areas beyond the cell's coverage, such as building basements. Therefore, wider coverage may be required than for other services offered in 5G communication systems. mMTC-enabled UEs must be configured as inexpensive UEs, and their batteries may not be frequently replaced. Consequently, a long battery life, such as 10 to 15 years, may be required.

[0051] Finally, URLLC is a cellular-based wireless communication service for mission-critical communications. For example, URLLC can be considered for remote control of robots or machinery, industrial automation, unmanned aerial vehicle services, remote healthcare, alarms, and other services. Therefore, the communication provided by URLLC may need to provide significantly low latency and significantly high reliability. For example, services supporting URLLC need to meet an air interface latency of less than 0.5 milliseconds and a reliability of less than or equal to 10 -5 Therefore, for services that support URLLC, the 5G system needs to provide a smaller transmission time interval (TTI) than other services. At the same time, it needs to allocate a wider range of resources within a frequency band to ensure the reliability of the communication link.

[0052] The three 5G services, eMBB, URLLC, and mMTC, can be multiplexed and transmitted in a single system. To meet the requirements of different services, different transmission or reception schemes and parameters can be used for each service.

[0053] Hereinafter, the frame structures of LTE and LTE-A systems will be described in more detail with reference to the accompanying drawings.

[0054] Figure 1 The time-frequency domain structure of the LTE communication system according to the embodiment of the present disclosure is described.

[0055] Reference Figure 1 , the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. In the time domain, the smallest transmission unit is the OFDM symbol. symbOFDM symbols 101 are grouped together to form a time slot 102, and two time slots are grouped together to form a subframe 103. The length of a time slot is 0.5 milliseconds, and the length of a subframe is 1.0 milliseconds. In addition, a radio frame 104 is a time domain unit consisting of 10 subframes. In the frequency domain, the smallest transmission unit is a subcarrier. The entire system transmission bandwidth may include a total of N BW Subcarriers 105. In the time-frequency domain, the basic resource unit is the resource element (RE) 106, which is represented by an OFDM symbol index and a subcarrier index. Resource blocks (RBs) (RBs or physical resource blocks (PRBs) 107 are represented by N in the time domain. symb consecutive OFDM symbols 101 and N in the frequency domain RB Thus, one RB in the continuous subcarriers 108 includes N symb ×N RB RE 106. Generally speaking, the minimum data transmission unit is RB. In LTE system, generally speaking, N symb =7, N RB =12, N BW and N RB It is proportional to the system transmission bandwidth.

[0056] Subsequently, downlink control information (DCI) in LTE and LTE-A systems will be described in detail.

[0057] In the LTE system, scheduling information associated with downlink or uplink data is transmitted from the eNB to the UE via DCI. DCI can operate by defining various formats and applying a DCI format determined by factors such as whether the scheduling information is associated with uplink or downlink data, whether the size of the control information is compact (small) DCI, whether spatial multiplexing using multiple antennas is applied, and whether the DCI is used for power control. For example, DCI format 1, which is scheduling control information associated with downlink data, can be configured to include at least the following control information.

[0058] - Resource Allocation Type 0 / 1 Flag: Indicates whether the resource allocation scheme is Type 0 or Type 1. Type 0 applies a bitmap approach and allocates resources in units of resource block groups (RBGs). In LTE systems, the basic scheduling unit is a resource block (RB), which is represented by time and frequency domain resources. In the Type 0 scheme, an RBG consists of multiple RBs and is used as the basic scheduling unit. Type 1 allows the allocation of predetermined RBs within an RBG.

[0059] - Resource Block Allocation: Indicates the RBs allocated for data transmission. The resources indicated are determined based on the system bandwidth and resource allocation scheme.

[0060] - Modulation and Coding Scheme (MCS): Indicates the modulation scheme used for data transmission and the size of the transport block (data to be transmitted).

[0061] -HARQ process number: indicates the HARQ process number.

[0062] -New data indicator: indicates HARQ initial transmission or retransmission.

[0063] - Redundancy version: indicates the redundancy version of HARQ.

[0064] - Transmit Power Control (TPC) Command for Physical Uplink Control Channel (PUCCH): indicates the transmit power control command of PUCCH (Uplink Control Channel).

[0065] The DCI undergoes channel coding and modulation processes and is then transmitted through the PDCCH (Downlink Physical Control Channel).

[0066] A cyclic redundancy check (CRC) is added to the payload of the DCI message, and the CRC is scrambled by the radio network temporary identifier (RNTI) corresponding to the UE identity. Different RNTIs can be used depending on the purpose of the DCI message, for example, UE-specific data transmission, power control commands, random access responses, etc. That is, the RNTI is not explicitly transmitted, but is transmitted by being included in the CRC calculation process. If the UE receives a DCI message transmitted on the PDCCH, the UE can use the allocated RNTI to identify the CRC. If the result of the CRC identification is correct, the UE can determine that the corresponding message is sent to the UE.

[0067] Figure 2 A downlink control channel of an LTE communication system according to an embodiment of the present disclosure is described.

[0068] Reference Figure 2, PDCCH 201 is time-multiplexed with PDSCH 202, which is a data transmission channel, and transmitted over the entire system bandwidth. The area of PDCCH 201 is expressed as the number of OFDM symbols, which is indicated to the UE by a control format indicator (CFI) transmitted via the physical control format indicator channel (PCFICH). By assigning PDCCH 201 to the OFDM symbol present in the front of the subframe, the UE is able to decode the downlink scheduling assignment as quickly as possible. Therefore, the decoding delay of the downlink shared channel (DL-SCH), that is, the overall downlink transmission delay, can be reduced. One PDCCH transmits one DCI information, and multiple UEs can be scheduled simultaneously in the downlink and uplink, so the transmission of multiple PDCCHs can be carried out simultaneously in each cell. The cell-specific reference signal (CRS) 203 is used as a reference signal for decoding PDCCH 201. CRS203 is transmitted for each subframe over the entire frequency band, and the scrambling and resource mapping may be different for each cell identity (ID). CRS 203 is a reference signal used by all UEs, so UE-specific beamforming may not be used. Therefore, the multi-antenna transmission scheme of LTE's PDCCH may be limited to an open-loop transmit diversity scheme. The UE implicitly obtains the port number of the CRS by decoding the Physical Broadcast Channel (PBCH).

[0069] The resource allocation of PDCCH 201 is carried out in units of control channel elements (CCEs), and one CCE includes 9 resource element groups (REGs), that is, a total of 36 resource elements (REs). The number of CCEs required for a specific PDCCH 201 can be 1, 2, 4 or 8, which can be different depending on the channel coding rate of the DCI message payload. As mentioned above, different numbers of CCEs can be used to implement link adaptation of PDCCH 201. The UE needs to detect the signal without knowing the information associated with the PDCCH 201. In LTE, a search space representing a set of CCEs is defined for blind decoding. The search space includes multiple sets according to the aggregation level (AL) of each CCE, which is not explicitly notified by a signal, but is implicitly defined by a function and subframe number associated with the UE identifier. In each subframe, the UE performs decoding of PDCCH 201 for all available resource candidates that can be formed by the CCEs in the configured search space, and processes the information declared as valid for the corresponding UE through CRC identification.

[0070] The search space can be divided into a UE-specific search space and a common search space. A group of UEs or all UEs can search the common search space of PDCCH 201 to receive cell-common control information, such as paging information or dynamic scheduling associated with system information. For example, scheduling allocation information for the DL-SCH, which transmits the System Information Block (SIB)-1 including cell operator information, can be received by searching the common search space of PDCCH 201.

[0071] In LTE, the entire PDCCH region includes a set of CCEs in a logical region, and there is a search space including a set of CCEs. The search space can be divided into a common search space and a UE-specific search space. The search space of LTE PDCCH can be defined as shown in Table 1.

[0072]

Table 1

[0073]

[0074]

[0075] According to the definition of the search space of the PDCCH shown in Table 1 above, the UE-specific search space is not explicitly notified by a signal, but is implicitly defined by a function associated with the UE identifier and the subframe number. That is, the UE-specific search space changes according to the subframe number, so this shows that the UE-specific search space can change over time. Therefore, the following problem (blocking problem) can be overcome: a specific UE cannot use the search space due to other UEs among multiple UEs. If the UE is not scheduled in the corresponding subframe because all CCEs investigated by the UE are currently used by other scheduled UEs in the same subframe, then since the search space is time-varying, this problem may not occur in subsequent subframes. For example, although the UE-specific search spaces of UE#1 and UE#2 partially overlap in a specific subframe, the overlap may be different in subsequent subframes because the UE-specific search space is different for each subframe.

[0076] According to the definition of the PDCCH search space, since a predetermined group of UEs or all UEs need to receive the PDCCH, the common search space is defined as a set of pre-agreed CCEs. In other words, the common search space does not change due to UE identity, subframe number, etc. Although there is a common search space used to transmit various system information, the common search space can also be used to transmit control information for a single UE. Therefore, the common search space can be used to solve the problem of UEs not being scheduled due to a lack of available resources in the UE-specific search space.

[0077] A search space is a set of candidate control channels formed by CCEs that a UE needs to attempt to decode at a given aggregation level. There are multiple aggregation levels, where one, two, four, and eight CCEs form a bundle, and the UE has multiple search spaces. In the LTE PDCCH, the number of PDCCH candidates a UE needs to monitor in the search space defined by aggregation level is defined in Table 2 below.

[0078]

Table 2

[0079]

[0080] According to Table 2, in the case of UE-specific search space, aggregation levels {1, 2, 4, 8} are supported, where {6, 6, 2, 2} PDCCH candidates can be given respectively. In the case of common search space, aggregation levels {4, 8} are supported, where {4, 2} PDCCH candidates can be given respectively. The reason why the common search space only supports aggregation levels {4, 8} is to improve coverage characteristics, because system information generally needs to reach the edge of the cell.

[0081] DCI transmitted in the common search space is defined as a specific DCI format (e.g., 0 / 1A / 3 / 3A / 1C) corresponding to purposes such as power control for UE groups or system messages. DCI formats with spatial multiplexing are not supported in the common search space. The downlink DCI format to be decoded in the UE-specific search space may vary depending on the transmission mode configured for the corresponding UE. The transmission mode is configured via RRC signaling, so the subframe number is not explicitly specified, which depends on whether the corresponding configuration is valid for the corresponding UE. Therefore, the UE always performs decoding for DCI format 1A regardless of the transmission mode to avoid loss of communication during operation.

[0082] Hereinabove, the search space and method of transmitting or receiving a downlink control channel and downlink control information in conventional LTE and LTE-A have been described.

[0083] Below, the downlink control channel in the 5G communication system will be described in more detail with reference to the accompanying drawings.

[0084] Figure 3 The basic unit of a downlink control channel in a 5G communication system according to an embodiment of the present disclosure is described.

[0085] according to Figure 3The basic unit of time and frequency resources (REG) configured for the control channel consists of one OFDM symbol 301 on the time axis and 12 subcarriers 302 on the frequency axis, i.e., one RB. By assuming one OFDM symbol 301 as the basic unit of time when configuring the basic unit of the control channel, the data channel and the control channel can be time-multiplexed within a subframe. By placing the control channel before the data channel, user processing time can be reduced, making it easier to meet delay requirements. By configuring the basic unit of the control channel on the frequency axis as one RB 302, frequency multiplexing between the control channel and the data channel can be effectively performed.

[0086] By connecting Figure 3 The REG 303 shown in FIG. 3 can configure the control channel region to various sizes. For example, when CCE 304 is the basic unit for allocating downlink control channels in 5G, one CCE 304 can include multiple REGs 303. Figure 3 For example, if REG 303 includes 12 REs and one CCE 304 includes six REGs 303, this means that one CCE 304 includes 72 REs. If a downlink control region is configured, the corresponding region includes multiple CCEs 304, and a specific downlink control channel can be transmitted by being mapped to one or more CCEs 304 in the control region according to an aggregation level (AL). CCEs 304 in the control region can be distinguished by numbers, and the numbers can be allocated according to a logical mapping scheme.

[0087] Figure 3 The basic unit of the downlink control channel, ie, REG 303, may include REs mapped to DCI and an area mapped to a demodulation reference signal (DMRS) 305 as a reference signal for decoding DCI. Figure 3 As shown, DMRS 305 can be transmitted using 6 REs within one REG 303. For reference, since DMRS 305 is transmitted using the same precoding as the control signal mapped in REG 303, the UE can decode the control information without the precoding information applied by the base station.

[0088] Figure 4 A control resource set (CORESET) through which a downlink control channel is transmitted in a 5G communication system according to an embodiment of the present disclosure is described.

[0089] Figure 4An example is described below where two control regions (control region #1 401 and control region #2 402) are allocated to a system bandwidth 410 on the frequency axis and one time slot 420 on the time axis (eg, Figure 4 (Assume that 1 time slot includes 7 OFDM symbols in the example). The control region 401 or 402 can be configured based on a specific subband 403 within the entire system bandwidth 410 on the frequency axis. The control region can be configured based on one or more OFDM symbols, which can be defined as the control region length (control resource set duration 404) in the time axis. Figure 4 In the example of FIG, control region #1 401 is configured based on a control resource set duration of 2 symbols, while control region #2 is configured based on a control resource set duration of 1 symbol.

[0090] As described above, the control region in 5G can be configured through higher-layer signaling (e.g., system information, master information block (MIB), radio resource control (RRC) signaling) from the eNB to the UE. Configuring the control region for the UE means providing information associated with the location of the control region, subbands, resource allocation of the control region, and control region length. For example, as shown in Table 3, this configuration may include the following information.

[0091]

Table 3

[0092]

[0093]

[0094] In addition to the configuration information described above, various information required for transmitting the downlink control channel may also be configured for the UE.

[0095] Next, the downlink control information (DCI) in 5G will be described in detail.

[0096] In the 5G system, scheduling information for uplink data (Physical Uplink Shared Channel (PUSCH)) or downlink data (Physical Downlink Shared Channel (PDSCH)) is transmitted from the base station to the UE via DCI. The UE can monitor the fallback DCI format and the non-fallback DCI format on the PUSCH or PDSCH. The fallback DCI format may include fixed fields between the base station and the UE, and the non-fallback DCI format may include configurable fields.

[0097] The fallback DCI format for scheduling PUSCH may include the following information, for example, as shown in Table 4.

[0098]

Table 4

[0099]

[0100]

[0101] The non-fallback DCI format for scheduling PUSCH may include the following information, for example, as shown in Table 5.

[0102]

Table 5

[0103]

[0104]

[0105] The fallback DCI format for scheduling PDSCH may include the following information, for example, as shown in Table 6-1.

[0106]

Table 6-1

[0107]

[0108]

[0109] The non-fallback DCI format for scheduling PDSCH may include the following information, for example, as shown in Table 6-2.

[0110]

Table 6-2

[0111]

[0112]

[0113] The DCI may undergo a channel coding and modulation process and may then be transmitted via the downlink physical downlink control channel (PDCCH). A cyclic redundancy check (CRC) is attached to the DCI message payload, and the CRC is scrambled by the radio network temporary identifier (RNTI) corresponding to the UE identifier. Different RNTIs are used depending on the purpose of the DCI message, such as UE-specific data transmission, power control commands, random access responses, etc. The RNTI is not transmitted explicitly, but is transmitted by being included in the CRC calculation process. After receiving the DCI message transmitted on the PDCCH, the UE checks the CRC by using the allocated RNTI. If the result of the CRC check is correct, it can be seen that the corresponding message has been transmitted to the UE.

[0114] For example, the DCI used to schedule PDSCH for system information (SI) may be scrambled by the SI-RNTI. The DCI used to schedule PDSCH for random access response (RAR) messages may be scrambled by the RA-RNTI. The DCI used to schedule PDSCH for paging information may be scrambled by the P-RNTI. The DCI providing slot format indicator (SFI) notification may be scrambled by the SFI-RNTI. The DCI providing transmit power control (TPC) notification may be scrambled by the TPC-RNTI. The DCI used to schedule UE-specific PDSCH or PUSCH may be scrambled by the cell RNTI (C-RNTI).

[0115] When a specific UE receives scheduling for a data channel (ie, PUSCH or PDSCH) through the PDCCH, a plurality of pieces of data are transmitted and received together with the DMRS in a scheduled resource region.

[0116] Figure 5 An example of a resource block structure according to an embodiment of the present disclosure is explained.

[0117] Figure 5 A case is described in which 14 OFDM symbols are configured to be used as one slot (or subframe) by a specific UE in the downlink, the first two OFDM symbols are used for PDCCH transmission, and the third symbol is used for DMRS transmission. Figure 5 In the LTE / LTE-A system, in a specific RB where PDSCH is scheduled, PDSCH is transmitted by mapping data to REs, wherein DRMS is not transmitted through REs of the third symbol and from the fourth symbol to the last symbol. Figure 5 The subcarrier spacing Δf can be 15kHz, and in the 5G system it can be one of {15, 30, 60, 120, 240, 480}kHz.

[0118] Meanwhile, in a cellular system, a base station needs to send a reference signal to measure the channel state of the downlink. In a 3GPP Long Term Evolution Advanced (LTE-A) system, a UE can measure the channel state between the base station and the UE by using a CRS or CSI-RS sent from the base station. The measurement of the channel state must take into account various factors and may include the amount of interference in the downlink. The amount of interference in the downlink may include interference signals generated by antennas belonging to neighboring base stations and thermal noise, which is very important for the UE to determine the channel condition of the downlink. For example, when a base station with one transmitting antenna sends a signal to a UE with one receiving antenna, the UE needs to determine Es / Io based on the reference signal received from the base station by determining the energy of each symbol that can be received through the downlink and the amount of interference received simultaneously in the portion where the corresponding symbol is received. The determined Es / Io can be converted into a data transmission speed or a numerical value corresponding thereto and sent to the base station in the form of a channel quality indicator (CQI) value, and can be used by the base station to determine the data transmission rate at which the base station performs data transmission to the UE.

[0119] In LTE-A systems, the UE can feed back information about the downlink channel state to the base station so that the base station can use this information for downlink scheduling. Specifically, the UE measures the reference signal transmitted by the base station in the downlink and feeds back information extracted from the reference signal to the base station in a format defined in the LTE / LTE-A standards. In LTE / LTE-A, the information fed back by the UE is called channel state information, which can include the following three pieces of information:

[0120] Rank Indicator (RI): The number of spatial layers that the UE can receive under the current channel state.

[0121] Precoding Matrix Indicator (PMI): an indicator of the precoding matrix preferred by the UE under the current channel state; and / or

[0122] Channel Quality Indicator (CQI): The maximum data rate at which a UE can receive data under the current channel conditions.

[0123] The CQI may be replaced by a signal-to-interference-plus-noise ratio (SINR), which may be used similarly to the maximum data rate, the maximum error correction code rate and modulation method, the data efficiency per frequency, and the like.

[0124] RI, PMI, and CQI are interrelated. For example, the precoding matrix supported in LTE / LTE-A has a different definition for each rank. Therefore, the PMI value "X" when the RI value is 1 and the PMI value "X" when the RI value is 2 may be interpreted differently. In addition, it is assumed that even if the UE determines the CQI, the rank and PMI notified to the base station by the UE itself will be applied in the base station. That is, if the UE notifies the base station of RI_X, PMI_Y, and CQI_Z, when the rank is RI_X and the PMI is PMI_Y, the UE can receive the data rate corresponding to CQI_Z. Therefore, the UE can assume a transmission method by which the UE performs transmission to the base station in the CQI calculation, thereby obtaining optimized performance when the corresponding transmission method is used for actual transmission.

[0125] In LTE / LTE-A, RI, PMI and CQI as channel state information fed back by the UE can be fed back periodically or aperiodically. When the base station wants to periodically obtain the channel state information of a specific UE, the base station can be configured to perform aperiodic feedback (or aperiodic channel state information report) by using a periodic feedback indicator (or channel state information request field, channel state information request information) included in the downlink control information (DCI) for the UE. In addition, when the UE receives an indicator configured to perform aperiodic feedback in the nth subframe, the UE can perform UL transmission by including aperiodic feedback information (or channel state information) in the data transmission of the (n+k)th subframe. Here, k is a parameter defined in the 3GPP LTE Release 11 standard, which can be 4 in frequency division duplex (FDD) and can be defined as shown in Table 7 in time division duplex (TDD).

[0126] Table 7: k value for each subframe number n in TDD UL / DL configuration

[0127]

[0128] When aperiodic feedback is configured, the feedback information (or channel state information) includes RI, PMI, and CQI, and according to the feedback configuration (or channel state report configuration), RI and PMI may not be fed back.

[0129] Below, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Below, the embodiments of the present disclosure will be described using LTE or LTE-A systems as examples, but the embodiments of the present disclosure can be applied to other communication systems with similar technical backgrounds or channel types. For example, 5G mobile communication technology (5G, New Radio (NR)) developed after LTE-A may be included therein. Therefore, the embodiments of the present disclosure can be applied to other communication systems with some modifications without significantly deviating from the scope of the present disclosure determined by those skilled in the art.

[0130] In addition, when it is determined that a detailed description of a related function or configuration may unnecessarily obscure the subject matter of the present disclosure, the detailed description thereof will be omitted. In addition, the terms to be described below are defined in consideration of the functions in the present disclosure, and these functions may vary according to the intentions or habits of the user or operator. Therefore, the definition needs to be made based on the content of the entire specification.

[0131] In the present disclosure, a method for using an OFDMA scheme that applies DFT precoding in the downlink is provided. In ultra-high frequency bands such as the terahertz band (e.g., from 95 GHz to 3 THz band) considered in 6G communication systems, the efficiency of the power amplifier (PA) may decrease. Generally speaking, the higher the peak-to-average power ratio (PAPR) of the signal input to the PA, the higher the output power backoff of the PA, and accordingly, the lower the output efficiency of the PA. Therefore, a technology for reducing or appropriately adjusting the signal PAPR is needed to improve the efficiency of the PA in ultra-high frequency bands. To this end, the downlink OFDMA method applying DFT precoding according to the embodiment includes a method for using DFT precoding for downlink transmission in a base station, a method for adjusting the size of the PAPR of the transmitted signal by adjusting the number and size of DFT precoding blocks, and a method for adjusting the backoff value of the power amplifier (PA) in the base station transmitter according to the size of the adjusted PAPR and adjusting the output power of the PA accordingly. All embodiments and combinations of embodiments disclosed herein are not limited to ultra-high frequency bands (e.g., the terahertz band) and can be applied to any frequency band in which a base station or UE operates.

[0132] Figure 6 The structure of a transmitter of a base station according to an embodiment of the present disclosure is explained.

[0133] Reference Figure 6, the transmitter of the base station may include a base station digital transmitter 601, a digital-to-analog converter (DAC) 602, and a radio frequency (RF) transmitter 603. The signal output from the digital transmitter 601 of the base station may be input to the digital-to-analog converter (DAC) 602 and converted into a baseband analog signal. The converted analog signal may be converted into a bandpass signal after being processed by the radio frequency (RF) transmitter 603, and then may be transmitted to the UE. The RF transmitter 603 of the base station may include a mixer, a phase shifter, and a PA for up-converting the baseband analog signal through a carrier frequency. The present disclosure includes a method for converting and controlling a PA back-off value in a base station according to the PAPR size of the baseband analog signal.

[0134] Figure 7 The structure of a digital transmitter of a base station according to an embodiment of the present disclosure is explained.

[0135] According to an embodiment, the digital transmitter of the base station may include: K ) for each of the UEs, which receives frequency division multiplexing (FDM); and a serial-to-parallel (S / P) converter, through which the signal output from the data modulator passes (indicated by reference numeral 701). The signals output from the data modulator and the S / P converter can be DFT-precoded in units of K blocks (indicated by reference numeral 702). According to an embodiment, the digital transmitter of the base station can adjust the number of DFT-precoding blocks (i.e., the number of UEs passing through FDM) and their respective sizes. The number of DFT-precoding blocks affects the PAPR of the transmitted signal. The PAPR value of each signal increases as the number of DFT-precoding blocks increases, and the PAPR value of each signal decreases as the number of DFT-precoding blocks decreases. For example, when a PA output of a specific size or greater is required, the base station can reduce the PAPR value of each signal by configuring the number of DFT-precoding blocks to be smaller and adjusting the PA back-off value accordingly to be smaller, thereby increasing the PA output. The base station can control each DFT-precoding block to have the same size, or can control each DFT-precoding block to have different sizes. The DFT-precoded signal for each UE may undergo a subcarrier mapping process and may be set on the frequency band scheduled for each UE (indicated by reference numeral 703). Here, the scheduling for each UE may be allocated to contiguous resource blocks or non-contiguous resource blocks. The subcarrier-mapped signal may undergo an IDFT process and then be converted into a time domain signal (indicated by reference numeral 704). The converted signal includes a cyclic prefix (CP) signal added thereto and may undergo a parallel-to-serial (P / S) converter process before being transmitted (indicated by reference numeral 705).

[0136] Figure 8The structure of a digital receiver of a UE according to an embodiment of the present disclosure is explained.

[0137] The time-domain digital signal received from the base station is converted to a frequency-domain signal by removing the CP, processing it through an S / P converter (indicated by reference numeral 801), and then through a DFT (indicated by reference numeral 802). The converted signal then passes through a subcarrier demapper 803 to allow the UE to select only its own signal. Since the corresponding signal is transmitted by the base station, after DFT precoding, it undergoes an IDFT process 804 before being sent to a demodulator 805.

[0138] FIG. 9A illustrates the operation of a base station according to an embodiment, and FIG. 9B illustrates the operation of a UE according to an embodiment of the present disclosure.

[0139] According to Figure 9A, the base station can determine the K value, which is the appropriate number of DFT precoding blocks in the digital transmitter (indicated by reference numeral 901). The base station can determine the PA back-off value of the RF transmitter based on the PAPR value of the transmitted signal, which is configured by the determined K value (indicated by reference numeral 902). The base station can send the determined K value to the UE (indicated by reference numeral 903), perform resource allocation based on the determined K value, configure DCI accordingly, and send the DCI to the UE (indicated by reference numeral 904). Thereafter, the base station can send the PDSCH to the UE based on the resource allocation configured in the DCI (indicated by reference numeral 905).

[0140] According to FIG9B , the UE may receive the determined K value from the base station (indicated by reference numeral 906). The UE may receive DCI including a resource allocation field from the base station and may interpret the resource allocation field in the DCI based on the received K value (indicated by reference numeral 907). The UE may receive the PDSCH based on the resource allocation field in the DCI (indicated by reference numeral 908).

[0141] Hereinafter, an example of a process in which the base station determines K, which is the number of DFT precoding blocks, will be described.

[0142] Figure 10 The following describes an example of a PA power backoff value configured by a base station according to the number K of DFT precoding blocks according to an embodiment. For a given number K of DFT precoding blocks in theory, when all DFT precoding blocks have the same size, the PAPR is the largest. In one embodiment, when all blocks have the same size, the PA power backoff value can be configured according to the PAPR, but is not limited thereto. The PA power backoff value can also be configured according to other standards. Figure 10As shown in Figure 1, as the number of DFT precoding blocks, K, increases, the corresponding PA rate backoff value also increases, and accordingly, the PA output can be reduced. Conversely, as the number of DFT precoding blocks, K, decreases, the corresponding PA power backoff value also decreases, and accordingly, the PA output can be increased. The base station can adjust the PA output according to the required PA output level by selecting an appropriate K value and the associated PA power backoff value. Figure 10 The specific values of K values and corresponding PA power back-off values disclosed in are only examples and do not limit the scope of the present disclosure.

[0143] Typically, if the K value is configured to be large and the PA power backoff value increases, the base station's PA output power will decrease accordingly, reducing communication coverage. However, since frequency domain resources can be more closely spaced, multi-user diversity gain can be increased through techniques such as channel-dependent scheduling. Conversely, if the K value is configured to be small and the PA power backoff value is reduced, the base station's PA output power will increase accordingly, thereby improving communication coverage. However, in the frequency domain, resources have no choice but to be operated in larger units, so the multi-user diversity gain may be reduced. Therefore, the base station can determine the optimal K value based on the trade-off between the required coverage and multi-user diversity gain in a given communication environment, and adjust the PA power backoff and PA output power accordingly. As an example of a given communication environment, if a small number of UEs are distributed at the cell edge, the base station can increase coverage by configuring a smaller K value. Furthermore, if a large number of UEs are distributed in close proximity, the base station can allocate resources to increase the multi-user diversity effect by configuring a larger K value.

[0144] under, Figures 11 to 14 Various embodiments of a method in which a base station notifies a UE of a determined K value, which is the number of DFT precoding blocks, are described.

[0145] The base station can perform scheduling or resource allocation for K UEs based on the K value, that is, the number of DFT precoding blocks. In addition, since the scheduling of the UE is performed based on the K value determined by the base station according to a given communication environment, the base station needs to notify the UE of the determined K value. As an example of a method for the base station to notify the UE of the determined K value, when referring to Figures 11 to 14 The K value, that is, the number of DFT precoding blocks determined by the base station, can be sent to the UE through system information (such as master information block (MIB) and system information block (SIB)), higher layer signaling (such as radio resource control (RRC)), or downlink control information (DCI).

[0146] Figure 11The present invention illustrates a case where a base station transmits a K value determined as the number of DFT precoding blocks to a UE through an MIB according to an embodiment of the present disclosure;

[0147] Figure 12 The present invention illustrates a case where a base station transmits a K value determined as the number of DFT precoding blocks to a UE through an SIB according to an embodiment of the present disclosure;

[0148] Figure 13 The present invention illustrates a case where a base station transmits a determined K value as the number of DFT precoding blocks to a UE through RRC according to an embodiment of the present disclosure;

[0149] Figure 14 The present invention illustrates a case where a base station transmits a determined K value as the number of DFT precoding blocks to a UE through a DCI according to an embodiment of the present disclosure;

[0150] The base station can be used Figures 11 to 14 Any one of the methods disclosed in or a combination of these methods is used to notify the UE of the K value determined as the number of DFT precoding blocks.

[0151] like Figure 14 As shown, when the UE receives the K value through DCI, the UE may not know the K value configured by the base station until it receives the PDCCH (through which the DCI is transmitted). Here, the base station can operate based on the value of K=1 when the PDCCH is transmitted. In addition, when a value of K>1 is used, for all K values, the UE can receive the PDCCH through blind decoding by using blocks of the same size.

[0152] Hereinafter, an embodiment of a method for determining the sizes of K DFT precoding blocks determined by a base station and configuring a resource allocation field included in a DCI accordingly will be described.

[0153] Figure 15 The case where the sizes of K DFT precoding blocks are controlled to be the same according to an embodiment of the present disclosure is described.

[0154] When the base station controls each DFT precoding block to have the same size and performs resource allocation for consecutive resource blocks, the base station can configure the frequency resource allocation field in the DCI based on the determined K DFT precoding blocks. Here, the base station can use a 1-bit field in the DCI to inform the UE that the respective block sizes are the same. The UE can determine the size of the inverse discrete Fourier transform (IDFT) of the receiving terminal based on the received K value and the size of the block. In an embodiment, the base station can configure the number of bits required for the resource allocation field in the DCI to be an integer greater than or equal to log2K. Here, each number of bits configuring the resource allocation field is an integer greater than or equal to log2K, which can represent the sequential position of the resource block group in the system bandwidth, and the specific UE is scheduled to this position.

[0155] When the base station controls each DFT precoding block to have the same size and allocates resources to consecutive resource blocks, the base station can configure the frequency resource allocation field in the DCI based on the determined K DFT precoding blocks. Here, the base station can use a 1-bit field in the DCI to inform the UE that the respective block sizes are the same. The UE can determine the size of the inverse discrete Fourier transform (IDFT) of the receiving terminal based on the received K value and block size. In an embodiment, the base station can use a bitmap scheme to configure the resource allocation field in the DCI. Here, the required number of bits can be configured to be the same as the number of blocks controlled by the base station. Each bit of the bitmap configuring the resource allocation field can represent the sequential position of the resource block group in the system bandwidth, and a specific UE is scheduled to this position.

[0156] Figure 16 A case where the sizes of K DFT precoding blocks are controlled to be different according to an embodiment of the present disclosure is described.

[0157] When the base station controls each DFT precoding block to have a different size and performs resource allocation for consecutive resource blocks, the base station can configure the frequency resource allocation field in the DCI according to the determined K DFT precoding blocks. Here, the base station can use a 1-bit field in the DCI to inform the UE that the block size is different. The UE can determine the size of the inverse discrete Fourier transform (IDFT) of the receiving terminal based on the received K value and block size. Here, the base station can transmit frequency domain scheduling information to a specific UE by using the resource block (RB) number or resource element (RE) number of the start and end point of the frequency band scheduled for the specific UE in the resource allocation field in the DCI.

[0158] When the base station controls the respective DFT precoding blocks so that they all have different sizes and performs resource allocation for non-contiguous resource blocks, the base station can configure the frequency resource allocation field in the DCI based on the determined K DFT precoding blocks. Here, the base station can use a 1-bit field in the DCI to inform the UE that the block sizes are different. The UE can determine the size of the inverse discrete Fourier transform (IDFT) of the receiving terminal based on the received K value and the block size. Here, the base station can use a bitmap scheme to configure the resource allocation field in the DCI. Here, the number of bits configuring the bitmap can be configured to be the same as the total number of RBs in the system bandwidth. Each bit of the bitmap configuring the resource allocation field can represent the sequential position of the resource block group in the system bandwidth, and the specific UE is scheduled to this position.

[0159] Figure 17 is a block diagram illustrating the structure of a base station according to an embodiment of the present disclosure.

[0160] Reference Figure 17 , the base station may include a base station receiver 1702, a base station transmitter 1703, and a base station processor 1701. The base station receiver 1702 and the base station transmitter 1703 may be referred to as a transceiver. The base station receiver 1702, the base station transmitter 1703, and the base station processor 1701 may operate according to the communication method of the above-mentioned base station. However, the elements of the base station are not limited to the above-mentioned examples. For example, the base station may include more or fewer elements than the above-mentioned elements (e.g., memory, etc.). In addition, the base station receiver 1702, the base station transmitter 1703, and the base station processor 1701 may be implemented in the form of a single chip.

[0161] The base station receiver 1702 and the base station transmitter 1703 (or transceiver) can transmit or receive signals to or from the UE. Here, the signals may include control information and data. To this end, the transceiver may include an RF transmitter that up-converts and amplifies the frequency of the transmitted signal and an RF receiver that performs low-noise amplification and down-converts the frequency of the received signal. However, the transceiver may be an example, and the components of the transceiver are not limited to the RF transmitter and RF receiver.

[0162] In addition, the transceiver can receive a signal through a wireless channel and can output the signal to the base station processor 1701, and can transmit a signal output from the base station processor 1701 through a wireless channel.

[0163] The memory (not shown) can store programs and data required for base station operation. In addition, the memory can store control information or data included in signals received from the base station. The memory includes a storage medium such as ROM, RAM, hard disk, CD-ROM, DVD, or a combination of storage media.

[0164] The base station processor 1701 may control a series of processes so that the base station can operate according to the above embodiments. The base station processor 1701 may be implemented by a controller or one or more processors.

[0165] Figure 18 is a block diagram illustrating the structure of a UE according to an embodiment of the present disclosure.

[0166] Reference Figure 18 , the UE may include a UE receiver 1802, a UE transmitter 1803, and a UE processor 1801. The UE receiver 1802 and the UE transmitter 1803 may be referred to as a transceiver. The UE receiver 1802, the UE transmitter 1803, and the UE processor 1801 of the UE may be operated by the UE according to the above communication method. However, the elements of the UE are not limited to the above examples. For example, the UE may include more or fewer elements than the above elements (e.g., memory, etc.). In addition, the UE receiver 1802, the UE transmitter 1803, and the UE processor 1801 may be implemented in the form of a single chip.

[0167] The UE receiver 1802 and the UE transmitter 1803 (or transceiver) can transmit or receive signals to or from the base station. Here, the signals may include control information and data. To this end, the transceiver may include an RF transmitter that up-converts and amplifies the frequency of the transmitted signal and an RF receiver that performs low-noise amplification and down-converts the frequency of the received signal. However, this is only one embodiment of a transceiver, and the components of the transceiver are not limited to an RF transmitter and an RF receiver.

[0168] In addition, the transceiver can receive a signal through a wireless channel, output the signal to the UE processor 1801, and can transmit a signal output from the UE processor 1801 through a wireless channel.

[0169] The memory (not shown) can store programs and data required for the UE to operate. In addition, the memory can store control information or data included in signals received from the UE. The memory can include a storage medium such as ROM, RAM, hard disk, CD-ROM, DVD, or a combination of storage media.

[0170] The UE processor 1801 may control a series of processes so that the UE can operate according to the above embodiments. The UE processor 1801 may be implemented by a controller or one or more processors.

[0171] At the same time, the embodiments disclosed in the specification and drawings are provided only as specific examples to facilitate explanation of the technical content of the present disclosure and to aid understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. In other words, it is obvious to those skilled in the art that various modifications can be made based on the technical scope of the present disclosure. In addition, the above-mentioned embodiments can be combined with each other as needed.

[0172] Although the present disclosure has been described with various embodiments, various changes and modifications may occur to those skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims.

Claims

1. A method for a base station in a communication system, the method comprising: determining a number of discrete Fourier transform (DFT) precoding blocks on which DFT precoding is performed; Determining a power back-off value of a power amplifier PA of the base station; Adjusting the output power of the PA of the base station according to the power backoff value; Sending information indicating the number of the DFT precoding blocks to the terminal; Sending downlink control information (DCI) to the terminal, where the DCI includes a resource allocation field configured based on the number of the DFT precoding blocks; as well as sending data to the terminal according to the resource allocation field included in the DCI, The number of the DFT precoding blocks is associated with a power backoff value of a PA of the base station.

2. The method according to claim 1, further comprising: The information indicating the number of the DFT precoding blocks is transmitted to the terminal through at least one of system information, radio resource control (RRC) signaling, or DCI.

3. The method according to claim 1, further comprising: Determine the number of DFT precoding block sizes, and The resource allocation field is configured based on the determined size of the DFT precoding block.

4. The method according to claim 3, wherein: The DCI includes information related to the determined size of the DFT precoding block.

5. A method for a terminal in a communication system, the method comprising: receiving, from a base station, information indicating a number of discrete Fourier transform (DFT) precoding blocks on which DFT precoding is performed; receiving downlink control information (DCI) from the base station, the DCI including a resource allocation field configured based on the number of the DFT precoding blocks; as well as receiving data from the base station based on the resource allocation field included in the DCI, The number of the DFT precoding blocks is associated with a power backoff value of a power amplifier PA of the base station, and the output power of the PA of the base station is adjusted according to the power backoff value of the PA.

6. The method according to claim 5, further comprising: The information indicating the number of the DFT precoding blocks is received from the base station through at least one of system information, radio resource control (RRC) signaling, or DCI.

7. The method according to claim 5, wherein: The size of the determined number of DFT precoding blocks is further determined by the base station, and The resource allocation field is configured based on the size of the DFT precoding block.

8. The method according to claim 7, wherein: The DCI includes information related to the size of the DFT precoding block.

9. A base station in a communication system, the base station comprising: transceiver; as well as a controller operatively connected to the transceiver, the controller being configured to: determining a number of discrete Fourier transform (DFT) precoding blocks on which DFT precoding is performed; Determining a power back-off value of a power amplifier PA of the base station; Adjusting the output power of the PA of the base station according to the power backoff value; Sending information indicating the number of the DFT precoding blocks to the terminal; Sending downlink control information (DCI) to the terminal, where the DCI includes a resource allocation field configured based on the number of the DFT precoding blocks; as well as sending data to the terminal according to the resource allocation field included in the DCI, The number of the DFT precoding blocks is associated with a power backoff value of a PA of the base station.

10. The base station according to claim 9, wherein: The controller is further configured to transmit information indicating the number of the DFT precoding blocks to the terminal through at least one of system information, radio resource control (RRC) signaling, or DCI. The base station according to claim 9 , wherein: The controller is further configured to: Determine the number of DFT precoding block sizes, and The resource allocation field is configured based on the determined size of the DFT precoding block; and The DCI includes information related to the determined size of the DFT precoding block.

12. A terminal in a communication system, the terminal comprising: transceiver; as well as a controller operatively connected to the transceiver, the controller being configured to: receiving, from a base station, information indicating a number of discrete Fourier transform (DFT) precoding blocks on which DFT precoding is performed; receiving downlink control information (DCI) from the base station, the DCI including a resource allocation field configured based on the number of the DFT precoding blocks; as well as receiving data from the base station based on the resource allocation field included in the DCI, The number of the DFT precoding blocks is associated with a power backoff value of a power amplifier PA of the base station, and the output power of the PA of the base station is adjusted according to the power backoff value of the PA.

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