KR20200061298A - Method for low latency communication in communication system supporting time division duplex mobile and apparatus therefor - Google Patents

Abstract

An operation method of a communication node is disclosed. According to an embodiment of the present invention, the operation method of a communication node may comprise the steps of: checking whether a slot immediately preceding a slot included in a frame is a downlink (DL) slot; when the immediately preceding slot is a DL slot, comparing whether a difference between a scheduling reference value targeting only downlink terminals for downlink communication of a first communication node and a scheduling reference value targeting both downlink and uplink terminals is greater than or equal to the magnitude of a first threshold set in advance; determining the transmission direction of the slot based on the comparison result; performing scheduling based on the determined transmission direction of the slot; and performing communication with a second communication node based on a result of the performed scheduling.

Description

METHOD FOR LOW LATENCY COMMUNICATION IN COMMUNICATION SYSTEM SUPPORTING TIME DIVISION DUPLEX MOBILE AND APPARATUS THEREFOR}

The present invention relates to a communication method and apparatus in a mobile communication system, and more particularly, to a low-delay communication method and apparatus in a time division duplex (TDD)-based mobile communication system.

Securing additional frequency bands to meet the rapidly growing demand for high-speed wireless data is not easy due to limited frequency resources. As a means for this, development of a mobile communication technology of the time division duplex (TDD) method, which is a technology for efficiently using the existing frequency band, is actively underway. In the TDD scheme using the same frequency band for uplink and downlink, various radio frames may be configured according to data (hereinafter referred to as "user traffic") characteristics. That is, the frequency can be efficiently used while meeting the data demand situation of the uplink and downlink through asymmetric resource allocation on the uplink and downlink.

On the other hand, the 5th generation mobile communication, which aims to support Gbps (Giga bps) level, which is at least 10 to 100 times the data transfer rate than the 4th generation mobile communication, uses tens of GHz (Giga Hertz) frequency bands as well as existing mobile communication frequency bands. It can contain. The 5th generation mobile communication includes not only enhanced mobile broadband (eMBB) for supporting ultra-high data rates, but also mass machine type communication (mMTC) for supporting the Internet of Things and ultra-reliable and low-latency communication (URLLC). It also aims to apply. In order to support URLLC, a transmission time interval (TTI) and a variety of immediate and variable slot structure utilization and control techniques may be required.

An object of the present invention to solve the above problems is to provide a frame structure, a TDD frame control method and apparatus for reducing delay time and improving transmission speed of a communication system based on a time division duplex (TDD). have.

Method for operating a communication node according to an embodiment of the present invention for solving the above problems is to determine whether the slot immediately before the slot included in the frame is a DL (downlink) slot, if the immediately preceding slot is a DL slot, the Compares whether a difference between a scheduling reference value targeting only a downlink terminal for downlink communication of a first communication node and a scheduling reference value targeting both downlink and uplink terminals is equal to or greater than a preset first threshold value Step, determining a transmission direction of the slot based on the comparison result, performing scheduling based on the determined transmission direction of the slot, and performing communication with a second communication node based on the performed scheduling result It may include steps.

According to the present invention, in a TDD (time division duplex)-based mobile communication system, the base station performs control on a frame based on dynamic resource allocation to perform communication with the terminal through a frame structure. Communication service can be provided.

According to the present invention, the base station can provide a low-latency communication service by configuring the frame into a DL (downlink) slot and an UL (uplink) slot.

According to the present invention, by configuring the frame in consideration of interference, the base station can select the optimal combination of the DL slot and the UL slot constituting the TDD frame. Therefore, the performance of the communication system can be improved.

1 is a conceptual diagram showing a first embodiment of a communication system.
2 is a block diagram showing an embodiment of a communication node constituting a communication system.
3 is a conceptual diagram showing a second embodiment of a communication system.
4 is a conceptual diagram illustrating a first embodiment of a frame structure in a communication system.
5 is a conceptual diagram illustrating a second embodiment of a frame structure in a communication system.
6 is a conceptual diagram illustrating a third embodiment of a frame structure in a communication system.
7 is a conceptual diagram for describing a slot switching probability of a frame in a communication system.
8 is a flowchart illustrating a first embodiment of a method for setting a slot of a frame in a communication system.
9 is a flowchart illustrating a second embodiment of a method for setting a slot of a frame in a communication system.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and/or includes a combination of a plurality of related described items or any one of a plurality of related described items.

When an element is said to be "connected" to or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but may exist in the middle. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle.

The terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “include” or “have” are intended to indicate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined in the present application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the overall understanding in describing the present invention, the same reference numerals are used for the same components in the drawings, and duplicate descriptions for the same components are omitted.

1 is a conceptual diagram showing a first embodiment of a communication system.

Referring to Figure 1, the communication system 100 is a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals (user equipment, 30-1, 130-2, 130-3, 130-4, 130-5, 130-6). Also, although not shown in the drawings, the communication system 100 may include a core network.

Here, the communication system may be referred to as a "communication network". A plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5) , 130-6) and each of the core networks may support at least one communication protocol.

For example, a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) and the core network are each based on a code division multiple access (CDMA) communication protocol, a wideband CDMA (WCDMA) based communication protocol, a time division multiple access (TDMA) based communication protocol, and FDMA (frequency). communication protocol based on division multiple access, communication protocol based on orthogonal frequency division multiplexing (OFDM), communication protocol based on orthogonal frequency division multiple access (OFDMA), single carrier (SC)-FDMA based communication protocol, NOMA (non- It can support communication protocols based on orthogonal multiple access, and communication protocols based on space division multiple access (SDMA). A plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5) , 130-6) and each of the core networks may have the following structure.

2 is a block diagram showing an embodiment of a communication node constituting a communication system.

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, and the like. Each of the components included in the communication node 200 may be connected by a bus 270 to communicate with each other. However, each component included in the communication node 200 may be connected through a separate interface or a separate bus centered on the processor 210, not the common bus 270. For example, the processor 210 may be connected to at least one of the memory 220, the transceiver 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface.

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be configured as at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may be configured as at least one of read only memory (ROM) and random access memory (RAM).

Referring back to FIG. 1, each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the coverage of the third base station 110-3. . The first terminal 130-1 may belong to the coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the coverage of the fifth base station 120-2.

Here, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) g node B (gNB; next generation Node B), Node B (NodeB), upgraded Node B (evolved NodeB), base transceiver station (BTS), radio base station, radio transceiver, access point, access node, road side unit (RSU), Referred to as a digital unit (DU), cloud digital unit (CDU), radio remote head (RRH), radio unit (RU), transmission point (TP), transmission and reception point (TRP), relay node, etc. Can be. Each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) is a terminal, an access terminal, a mobile terminal, It may be referred to as a station, a subscriber station, a mobile station, a portable subscriber station, a node, a device, or the like.

A plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5 , 130-6) Cellular communication (e.g., LTE (long term evolution), LTE-A (advanced), 5G NR (new RAT), etc., defined in the 3rd generation partnership project (3GPP) standard) I can apply.

Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to each other through an ideal backhaul or a non-ideal backhaul, and the ideal backhaul Alternatively, information can be exchanged with each other through a non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to a core network (not shown) through an ideal backhaul or a non-ideal backhaul. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) receives a signal received from the core network corresponding to the terminal (130-1, 130-2, 130-3, 130) -4, 130-5, 130-6), and the core network receives signals received from the corresponding terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6. Can be transferred to.

Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can support OFDMA-based downlink transmission, and SC-FDMA-based uplink (uplink) ) Can support transmission. In addition, each of a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) multiple input multiple output (MIMO) transmission (eg, single user (SU)-MIMO, MU (multi user)-MIMO, massive MIMO, etc., CoMP (coordinated multipoint) transmission, carrier aggregation transmission, transmission in an unlicensed band, device-to-device (D2D) Communication (or ProSe (proximity services), etc. can be supported. Here, a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) each of the base station ( Operation corresponding to 110-1, 110-2, 110-3, 120-1, 120-2), supported by base stations 110-1, 110-2, 110-3, 120-1, 120-2 Can be performed.

Core networks include application function (AF), access and mobility management function (AMF), authentication server function (AUSF), network exposure function (NEF), network repository function (NRF), network slice selection function (NSSF), and policy (PCF). control function (SMF), session management function (SMF), unified data management (UDM), and user plane function (UPF). The structure of the core network may be a structure in which AMF and SMF are separated from the core network.

The AMF can manage the location information and mobility information of the terminal. The AMF may be connected to the terminal through an N1 reference point, and may be connected through a base station (radio access network, (RAN)) and an N2 reference point. In addition, the AMF may transmit location information and mobility information of the terminal received from the base station and the terminal to the core network through the Namf basic interface connected to the core network.

The SMF can process a function of managing a PDU session, such as establishing, changing, and releasing a protocol data unit (PDU) session connected between the terminal and the base station and the core network. The SMF can be connected to the core network through the Nsmf basic interface, and can be connected through the UPF and N4 reference points. UPF can be connected through SMF and N4 reference point, and can establish a session between the terminal and the core network by approving the session connection request from SMF.

3 is a block diagram showing an embodiment of a communication system according to a second embodiment of the present invention.

Referring to FIG. 3, the communication system may include a plurality of terminals 311 and 312 and a base station 320. The plurality of terminals 311 and 312 and the base station 320 may be configured the same or similar to the terminal 130 and the base stations 110 and 120 of FIG. 1. The plurality of terminals 311 and 312 may communicate with the base station 320. The plurality of terminals 311 and 312 may dynamically communicate with the base station 320 based on the configuration of a time division duplex (TDD) frame.

The plurality of terminals 311 and 312 may transmit data to the base station 320 through an uplink (UL) channel during the same time period, and from the base station 320 through a downlink (DL) channel. Data can be received. For example, the first terminal 311 may receive data from the base station 320 through a downlink channel. The second terminal 312 may transmit data to the base station 320 through an uplink channel. Here, the downlink channel may be a physical downlink shared channel (PDSCH) and the uplink channel may be a physical uplink shared channel (PUSCH). The base station 320 may transmit data to the first terminal 311 through the downlink and receive data from the second terminal 312 through the uplink.

The base station 320 may configure a frame. Here, the frame may be a dynamic time division duplex frame (TDD frame). The frame may include a plurality of slots. Each of the plurality of slots may include one or more OFDM symbols. The plurality of slots may be a downlink control (DLC) slot, a downlink (DL) slot, an uplink (UL) slot, and a switching gap (SG) slot. Here, the DLC slot may be a slot for setting the remaining slots constituting the frame, the DL slot may be used to perform downlink communication between the terminal 311 and the base station 320, and the UL slot is a terminal ( 312) and the base station 320 may be used to perform uplink communication. In addition, the SG slot may be used to switch to uplink communication after downlink communication, between downlink communication between the base station 320 and the first terminal 311 and between the base station 320 and the second terminal 312. It can be used to minimize interference that occurs between uplink communications. The base station can configure the frame in the following way.

4 is a conceptual diagram illustrating a first embodiment of a frame structure in a communication system.

Referring to FIG. 4, a frame (eg, a subframe 400) may include N_s slots 401 to 412, and each of the slots may include N_sym symbols. Each of N_s and N_sym may be a natural number. Here, N_sym may be set to 1.

The first slot 401 in the frame 400 may be set as a DLC slot. The DLC slot may be used for transmission of control information (eg, downlink control information (DCI)) to a terminal (eg, the first terminal 311 and the second terminal 312 of FIG. 3). Among the slots constituting the frame 400, each of the remaining slots 402 to 412 except for the first slot 401 may be set to a DL slot, an UL slot, or an SG slot (eg, a flexible slot). . For example, the second slot 402 may be set as a DL slot, the third slot 403 may be set as an SG slot, and the fourth slot 404 may be set as an UL slot.

The transmission direction of each of the remaining slots 402 to 412 in the frame 400 may be set by a base station (for example, the base station 320 of FIG. 3). For example, the base station may generate a DCI including transmission direction information indicating a transmission direction (eg, DL, UL, SG) of each of the slots 402 to 412 in the frame 400. The DCI may further include resource allocation information indicating resources allocated for the UE in the frame.

The UE may receive the DCI from the base station by performing a monitoring operation in the DLC slot (eg, the first slot 401), and slots configuring the frame 400 based on transmission direction information included in the DCI Each transmission direction (402 to 412) can be confirmed.

The terminal may perform downlink communication or uplink communication using resources indicated by resource allocation information included in DCI. For example, the terminal may perform downlink communication with the base station through the second slot 402, and may perform uplink communication with the base station through the fourth slot 404.

Meanwhile, the first slot 401 may be a DCL slot, and the second slot 402 and the third slot 403 may be set to DL slots and UL slots, respectively. In this case, the second slot 402 may be in DL intf state. The DL intf state may mean that the UE transmits downlink data to the UE just before the UE transmits uplink data.

For example, the terminal may receive the DCI from the base station through the first slot 401. The UE may perform downlink communication with the base station using the second slot based on the received DCI, and perform uplink communication with the base station using the third slot.

5 is a conceptual diagram illustrating a second embodiment of a frame structure in a communication system.

Referring to FIG. 5, a frame (eg, a subframe 500) may include N_s slots 501 to 512, and each of the slots may include N_sym symbols. Each of N_s and N_sym may be a natural number.

The slots 501 to 512 in the frame 500 may be set to any one of DL slot, SG slot, and UL slot. The DL slot may be used to transmit control information (eg, DCI) to a terminal (eg, first terminal 311 and second terminal 312 of FIG. 3), and a terminal and a base station (eg, It can be used to perform downlink communication between the base station (320) of FIG. In addition, the UL slot may be used to perform uplink communication between the terminal and the base station, and the SG slot may be used to switch to uplink communication after downlink communication.

The UE may receive the DCI from the base station by performing a monitoring operation in the DL slot (eg, the first slot 501 or the third slot 503), and the frame (based on the transmission direction information included in the DCI) The transmission direction of each of the slots 501 to 512 constituting 500) may be confirmed.

The UE may perform downlink communication or uplink communication using resources indicated by resource allocation information included in DCI. For example, the terminal may perform downlink communication with the base station using the third slot 503, and may perform uplink communication with the base station using the fifth slot 505.

Meanwhile, the third slot 503 may be a DL slot, and the fourth slot 504 may be set as a UL slot. In this case, the third slot 503 may be in DL intf state. The base station may transmit a DCI including uplink resource allocation information to the terminal through the third slot 503. The UE may receive the DCI through the third slot 503, and may perform uplink communication with the base station using the fourth slot 504 indicated by the received DCI.

6 is a conceptual diagram illustrating a third embodiment of a frame structure in a communication system.

Referring to FIG. 6, the frame 600 may include a first carrier 610 and a second carrier 630. The first carrier 610 may be a frequency division duplex (FDD)-based carrier, and the second carrier 630 may be a dynamic TDD-based carrier. Referring to FIG. 6, the first carrier 610 and the second carrier 630 may include N_s slots 611 to 622 and 631 to 642, respectively. Each of the slots may include N_sym symbols. Each of N_s and N_sym may be a natural number.

The slots 611 to 622 of the first carrier 610 may be set as a DLC slot. The DLC slot can be used for transmission of control information (eg, DCI). Each of the slots 631 to 642 of the second carrier 630 may be set to a DL slot, a UL slot, or an SG slot (eg, a flexible slot). For example, the base station (for example, the base station 320 of FIG. 3) may set the first slot of the second carrier 630 as a DL slot, and set the fourth slot 634 as an SG slot, The fifth slot 635 may be set as an UL slot.

The transmission direction of each of the slots 631 to 642 of the second carrier 630 may be set by a base station (eg, the base station 320 of FIG. 3. The base station transmits each of the slots 631 to 642) A DCI including transmission direction information indicating a direction (eg, DL, UL, SG) may be generated.The DCI may further include resource allocation information indicating resources allocated for the UE in the frame. The base station may transmit DCI to the terminal using slots 611 to 622 of the first carrier 610.

The UE may receive the DCI from the base station by performing a monitoring operation in the DLC slot (for example, any one of the slots 611 to 622 of the first carrier 610), and the transmission direction information included in the DCI Based on this, the transmission direction of each of the slots 631 to 642 constituting the second carrier 630 may be confirmed.

The terminal may perform downlink communication or uplink communication using resources indicated by resource allocation information included in DCI. For example, the terminal may perform downlink communication with the base station through the first slot 631 of the second carrier 630, and may perform uplink communication with the base station through the fifth slot 635. .

Meanwhile, the first slot 611 of the first carrier 610 may be a DLC slot, the first slot 631 of the second carrier 630 is a DL slot, and the second slot 632 is a UL slot Each can be set. In this case, the first slot 631 of the second carrier 630 may be in DL intf state. The terminal may receive data from the base station through the first slot 631 of the second carrier 630, and may transmit data to the base station through the second slot 632.

Meanwhile, the third slot 633 of the second carrier 630 may be set as a DL slot, and the fourth slot 634 may be set as a UL slot. In this case, the third slot 633 may be in DL intf state. For example, the UE may receive DCI from the base station through the third slot 613 of the first carrier 610. The UE may perform downlink communication with the base station using the third slot 633 of the second carrier 630 based on the received DCI, and uplink communication with the base station using the fourth slot 634. You can do

Referring back to FIG. 3, communication between the first terminal 311 and the base station 320 and communication between the second terminal 312 and the base station 320 may act as interference with each other. Propagation delay may occur in downlink communication between the base station 320 and the first terminal 311. Here, the propagation delay may be caused by a distance between the first terminal 311 and the base station 320. Due to the propagation delay, transmission of data transmitted from the base station 320 to the first terminal 311 may be delayed, and transmission delay may act as interference in communication between the second terminal 312 and the base station 320. .

In addition, frame transmission of the second terminal 312 may be delayed by timing advance in uplink communication between the base station 320 and the second terminal 312. The timing advance is for compensating for the transmission delay time according to the distance between the second terminal 312 and the base station 320, and may be determined according to the relative distance between the second terminal 312 and the base station 320. That is, the second terminal 312 may delay frame transmission by a time corresponding to the timing advance value, and the transmission delay may act as interference in communication between the first terminal 311 and the base station 320. When interference due to transmission delay occurs, the signal noise ratio (SNR) of the terminal may be expressed as in Equation 1 below.

는 단말의 SNR일 수 있고,

는 간섭이 없을 때의 하향링크 단말(예를 들어 제1 단말(311))의 SNR 예상 값일 수 있고,

은 전체 프레임의 샘플 수일 수 있으며,

는 기지국(320)의 하향링크 전송의 전파 지연시간 및 상향링크 단말(예를 들어 제2 단말(312))의 타이밍 어드밴스에 의하여 신호가 겹치는 샘플의 개수일 수 있고,

는 단말과 기지국(320)의 상향링크 통신이 단말과 기지국(320)의 하향링크 통신에 미치는 간섭의 크기를 나타낼 수 있다. 기지국(320)은 간섭을 최소화하고, 네트워크 전송량을 최대화 하기 위하여, 다양한 방법으로 슬롯을 설정할 수 있다.In Equation 1

May be the SNR of the terminal,

May be an SNR estimated value of a downlink terminal (for example, the first terminal 311) when there is no interference,

Can be the number of samples in the entire frame,

May be the number of samples in which the signal overlaps due to the propagation delay time of the downlink transmission of the base station 320 and the timing advance of the uplink terminal (for example, the second terminal 312),

Can indicate the amount of interference between uplink communication between the terminal and the base station 320 on downlink communication between the terminal and the base station 320. The base station 320 can set slots in various ways to minimize interference and maximize network transmission.

7 is a conceptual diagram for describing a slot switching probability of a frame in a communication system.

Referring to FIG. 7, the terminal of FIG. 7 may be configured the same as or similar to the terminal 311. 312 of FIG. 3. The first slot 710 may be a DL slot, the second slot may be an UL slot, and the third slot 730 may be an SG slot. The base station may set a slot based on DTMC (Discrete Time Markov Chain). The transmission direction of the slot may be switched from the current transmission direction to UL, DL, or SG.

일 수 있고, UL 슬롯이 DL 슬롯으로 전환될 확률은

일 수 있다. 예를 들어, 제1 슬롯(710)이 DL 슬롯, UL 슬롯 및 SG 슬롯 가운데 어느 하나로 설정될 확률은 다음 수학식 2와 같을 수 있다.The probability that a DL slot is converted to a UL slot is

It may be, the probability that the UL slot is converted to a DL slot

Can be For example, the probability that the first slot 710 is set to one of the DL slot, the UL slot, and the SG slot may be as shown in Equation 2 below.

는 제1 슬롯(710)이 DL 슬롯으로 설정될 확률일 수 있고,

는 제1 슬롯(710)이 SG 슬롯으로 설정될 확률일 수 있으며,

는 제1 슬롯(710)이 UL 슬롯으로 설정될 확률일 수 있다 In Equation 2,

May be a probability that the first slot 710 is set as a DL slot,

May be a probability that the first slot 710 is set as an SG slot,

May be a probability that the first slot 710 is set to the UL slot

8 is a flowchart illustrating a first embodiment of a method for setting a slot of a frame in a communication system. 8 may include FIGS. 8A and 8B.

Referring to FIG. 8, the terminal and the base station of FIG. 8 may be configured to be the same as or similar to the terminals 311 and 312 and the base station 320 of FIG. 3. In addition, the frame of FIG. 8 may be the same as or similar to the frame 400 of FIG. 4, the frame 500 of FIG. 5, and the frame 600 of FIG. 6.

The base station may check whether the transmission direction of the immediately preceding slot is the DL slot at the time of setting the slot direction (S805). When the transmission direction of the immediately preceding slot is a DL slot (YES in S805), the base station determines whether the difference between the first metric and the second metric (first metric-second metric) is less than a first preset value. It can be confirmed (S810). Here, the base station can calculate the metric value by performing the following equations 3 to 7.

는 시간 t에서의 메트릭일 수 있고,

는 시간 t에서 기지국의 하향링크 대기열의 길이 또는 단말의 상향링크 대기열의 길이일 수 있고,

는 시간 t에서 기지국이 단말에 전송하는 하향링크 데이터의 전송량 또는 상향링크 통해 단말이 기지국에 전송하는 상향링크 데이터의 전송량일 수 있다. 여기에서 기지국의 하향링크 대기열의 길이는 기지국의 송신 버퍼에 저장된 데이터들의 크기의 합일 수 있고, 단말의 상향링크 대기열의 길이는 단말의 송신 버퍼에 저장된 데이터들의 크기의 합일 수 있다.In Equation 3

Can be the metric at time t,

May be the length of the downlink queue of the base station or the length of the uplink queue of the terminal at time t,

May be the amount of downlink data transmitted by the base station to the terminal at time t or the amount of uplink data transmitted by the terminal to the base station through the uplink. Here, the length of the downlink queue of the base station may be the sum of the size of data stored in the transmission buffer of the base station, and the length of the uplink queue of the terminal may be the sum of the size of data stored in the transmission buffer of the terminal.

일 수 있고, 제2 메트릭은 하량링크 단말들 및 상향링크 단말들을 모두 대상으로 하는 경우의 최소

일 수 있다.When the immediately preceding slot is the DL slot in the corresponding slot (the slot for setting the direction), the first metric is the minimum when only the downlink terminals are targeted.

May be, the second metric is the minimum when both the downlink terminal and the uplink terminal

Can be

차이가 제1 설정값 이상인지 확인할 수 있다. 반대로 직전 슬롯이 UL 슬롯인 경우, 제3 메트릭은 상향링크 단말들만을 대상으로 한 경우의 최소

일 수 있고, 제2 메트릭은 하향링크 및 상향링크 단말들을 모두 대상으로 하는 경우의 최소

일 수 있다. 즉, 기지국은 UL 단말들을 대상으로 하는

와 DL 및 UL 단말을 모두 대상으로 하는 최소

의 차이가 제2 설정값 이상인지 확인할 수 있다. 또는, 메트릭은 아래 수학식 4와 같이 정의될 수 있다.That is, the base station is the minimum for both M(t) for downlink terminals and downlink terminals and uplink terminals.

It can be confirmed whether the difference is greater than or equal to the first set value. Conversely, if the immediately preceding slot is a UL slot, the third metric is the minimum when targeting only uplink terminals.

May be, the second metric is the minimum when targeting both downlink and uplink terminals

Can be That is, the base station targets UL terminals

And minimum for both DL and UL terminals

It can be confirmed whether the difference of is equal to or greater than the second set value. Alternatively, the metric may be defined as Equation 4 below.

는 패널티(penalty) 함수로써, 예를 들면 전송 지연에 관한 함수일 수 있다. 기지국은 수학식 4의

를 최소화하는 방향으로 프레임의 슬롯을 설정할 수 있다.In Equation 4

Is a penalty function, and may be, for example, a function related to transmission delay. The base station is

The slot of the frame can be set in a direction to minimize.

는 가중치 파라미터일 수 있으며, 페널티 함수의 중요도에 대한 것일 수 있다. 수학식 3과 마찬가지로 제1 메트릭은 하향링크 단말들만을 대상으로 하는 최소

일 수 있고, 제2 메트릭은 하향링크 단말들 및 상향링크 단말들을 모두 포함하는 최소

일 수 있다. 즉, 기지국은 두 기준 값의 차이가 제1 설정값 이상인지 확인할 수 있다. 또는, 메트릭은 아래 수학식 5와 같이 정의될 수 있다.

May be a weight parameter, and may be for the importance of the penalty function. As in Equation 3, the first metric is a minimum targeting only downlink terminals.

May be, the second metric is the minimum including both downlink terminals and uplink terminals

Can be That is, the base station can determine whether the difference between the two reference values is greater than or equal to the first set value. Alternatively, the metric may be defined as Equation 5 below.

는 시간 t에서 기지국이 단말에 전송하는 하향링크 데이터의 순시 전송량 또는 단말이 기지국에 전송하는 상향링크 데이터의 순시 전송량일 수 있고,

는 시간 t에서의 가상 대기열일 수 있다. 여기에서 가상 대기열은 아래 보조변수

의 크기만큼의 가상 데이터 패킷이 입력된다고 가정할 때의 기지국 또는 단말의 가상 대기열의 크기일 수 있다.

는 다음 수학식 6과 같이 나타낼 수 있다.In Equation 5,

May be an instantaneous transmission amount of downlink data transmitted from the base station to the terminal at time t or an instantaneous transmission amount of uplink data transmitted from the terminal to the base station,

May be a virtual queue at time t. Here, the virtual queue is the auxiliary variable below.

It may be the size of the virtual queue of the base station or the terminal when it is assumed that a virtual data packet of the size of is input.

Can be expressed as Equation 6 below.

는 시간 t-1에서의 보조 변수일 수 있다. 시간 t에서의 보조 변수

는 다음 수학식 7과 같이 나타낼 수 있다.From here,

May be an auxiliary variable at time t-1. Auxiliary variable at time t

Can be expressed as Equation 7 below.

는 보조변수

를 인자로 하는 목적함수일 수 있다. 예를 들어,

는 네트워크 효용 (Utility)을 최대화 하기 위해서는 로그 (Log) 함수의 합으로 사용할 수 있다.Function in equation (7)

Is an auxiliary variable

It may be an objective function taking as a factor. For example,

Can be used as the sum of the log functions to maximize network utility.

When the difference value between the first metric and the second metric is equal to or less than the first set value (YES in S810), the base station may set the slot as a DL slot (S815). The base station may schedule to perform downlink communication with the terminal using the DL slot (S820). The base station may generate a DCI including information about scheduling, and may transmit DCI to the terminal (S825). The terminal may receive the DCI from the base station, and may perform downlink communication with the base station based on scheduling information included in the DCI (S830).

When the difference value between the first metric and the second metric is greater than or equal to the first set value (No in S810), the base station may set the slot as the SG slot, and the next slot in the corresponding slot may be set as the UL slot (S835). The base station may schedule to perform uplink communication with the terminal using the UL slot (S840). The base station may generate a DCI including information about scheduling, and may transmit DCI to the terminal (S845). The terminal may receive the DCI from the base station, and may perform uplink communication with the base station based on scheduling information included in the DCI (S850).

On the other hand, if the slot immediately before the corresponding slot is not a DL slot (No in S805), the base station may check whether the immediately preceding slot is a UL slot (S855). If the immediately preceding slot is not the UL slot (No in S855), the base station may perform uplink transmission. When the slot is an UL slot (YES in S855), it may be confirmed whether the difference between the third metric and the second metric (third metric-second metric) is greater than or equal to the second set value (S860). The second set value may be the same or different from the first set value.

Here, the third metric and the second metric may be calculated in the same way as in S810. For example, if the third metric and the second metric are calculated based on Equation 3 in step S810, the third metric and the second metric may be calculated based on Equation 3 in step S865.

When the first metric and the second metric are calculated based on Equation 4 in step S810, the third metric and the second metric may be calculated based on equation 4 in step S860, and Equation 5 is calculated in step S810. When the first metric and the second metric are calculated on the basis, the third metric and the second metric may also be calculated based on Equation 5 in step S860.

When the difference value between the third metric and the second metric is greater than or equal to the second threshold (YES in S840), the base station may set the slot as a DL slot (S865). The base station may schedule to perform downlink communication with the terminal using the DL slot. The base station may generate a DCI including information about scheduling, and may transmit DCI to the terminal (S875). The terminal may receive the DCI from the base station, and may perform downlink communication with the base station based on scheduling information included in the DCI (S880).

When the difference value between the first metric and the second metric is less than the second threshold (No in S860), the base station may set the slot to the UL slot (S885). The base station may schedule to perform uplink communication with the terminal using the UL slot (S890). The base station may generate a DCI including information about scheduling, and may transmit DCI to the terminal (S895). The terminal may receive the DCI, and may perform uplink communication with the base station based on the scheduling information included in the DCI (S900).

However, the base station may configure a frame that does not include an SG slot. In this case, the frame may not include an SG slot for switching to uplink communication after downlink communication. When the frame does not include an SG slot, a method of setting the frame may be as follows.

9 is a flowchart illustrating a second embodiment of a method for setting a slot of a frame in a communication system. 9 may include FIGS. 9A and 9B.

Referring to FIG. 9, the terminal and the base station of FIG. 9 may be configured to be the same or similar to the terminals 311 and 312 and the base station 320 of FIG. 3. In addition, the frame of FIG. 9 may be the same as or similar to the frame 400 of FIG. 4, the frame 500 of FIG. 5, and the frame 600 of FIG. 6.

The base station can determine which one of the slots of the frame is a DL slot (S905). When the slot immediately before the corresponding slot is a DL slot, it may be confirmed whether the difference between the first metric and the second metric (first metric-second metric) is equal to or greater than a first preset value (S910). Here, the first metric and the second metric may be calculated based on any one of Equations 3 to 5 described in step S810 of FIG. 8.

When the difference value between the first metric and the second metric is less than the first set value (YES in S910), the base station may set the slot as a DL slot (S915). The base station may schedule to perform downlink communication with the terminal using the DL slot (S920). The base station may generate and transmit the DCI including the scheduling information to the terminal (S925). The terminal may receive the DCI, and may perform downlink communication based on scheduling information included in the DCI (S930).

When the difference value between the first metric and the second metric is equal to or greater than a first preset value (No in S910). The base station may set the slot as a DL slot, and the next slot of the corresponding slot may be set as a UL slot (S935). That is, when switching from the DL slot to the UL slot, a separate SG slot may not be required, and the UL slot may be set as a slot immediately after the DL slot. The base station may schedule to perform downlink communication with the terminal using the DL slot, and may schedule to perform uplink communication with the terminal using the UL slot (S940). At this time, the base station may determine the pair of the DL terminal to be received in the DL slot and the UL terminal to be transmitted in the UL slot immediately, and the SNR in the DL slot for each candidate UL terminal in the UL slot immediately using Equation (1). It can be predicted, and it can be used to predict the amount of transmission in the DL slot.

Meanwhile, when the SNR of the downlink terminal is equal to or less than a preset value (see FIG. 3 ), the base station may instruct the terminal to perform a clipping operation. Here, clipping may mean that the terminal does not receive the data of the part where interference occurs. The base station may generate and transmit the DCI including the scheduling information to the terminal (S945). The terminal may receive the DCI, and may perform downlink communication and uplink communication with the base station based on the scheduling information included in the DCI (S950).

On the other hand, if the immediately preceding slot is not a DL slot (No in S905), the base station can determine whether the slot is a UL slot (S955). If the slot is not an UL slot (No in S935), the base station may end control. When the slot is an UL slot (YES in S935), it can be determined whether the difference between the third metric and the second metric (third metric-second metric) is greater than or equal to the second set value (S960). Here, the third metric and the second metric may be calculated in the same way as in S910. For example, if the first metric and the second metric are calculated based on Equation 3 in step S910, the third metric and the second metric may be calculated based on Equation 3 in step S960.

If the first metric and the second metric are calculated based on Equation 4 in step S910, the third metric and the second metric may be calculated based on equation 4 in step S960, and Equation 5 is calculated in step S910. When the first metric and the second metric are calculated on the basis, the third metric and the second metric may also be calculated based on Equation 5 in step S960.

When the difference value between the third metric and the second metric is greater than or equal to the second threshold (YES in S960), the base station may set the slot as a DL slot (S965). The base station may schedule to perform downlink communication with the terminal using the DL slot (S970). The base station may generate and transmit a DCI including scheduling information to the terminal (S975). The UE may receive the DCI, and may perform downlink communication based on scheduling information included in the DCI (S980).

When the difference value between the third metric and the second metric is greater than or equal to the second threshold (No in S960), the base station may set the slot to the UL slot (S985). The terminal may transmit UL data to the base station using the UL slot. The base station may schedule to perform uplink communication with the terminal using the UL slot (S990). The base station may generate a DCI including information about scheduling, and may transmit DCI to the terminal (S995). The terminal may receive the DCI, and may perform uplink communication with the base station based on the scheduling information included in the DCI (S1000).

example The methods according to the invention are implemented in the form of program instructions that can be executed through various computer means and can be recorded on a computer readable medium. Computer-readable media may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention or may be known and usable by those skilled in computer software.

Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as roms, rams, flash memories, and the like. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, etc., as well as machine code such as that produced by a compiler. The above-described hardware device may be configured to operate with at least one software module to perform the operation of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. Will be able to.

Claims (1)

As a method of operation of the first communication node,
Checking whether a slot immediately before the slot included in the frame is a downlink (DL) slot;
When the immediately preceding slot is a DL slot, a difference between a scheduling reference value targeting only downlink terminals for downlink communication of the first communication node and a scheduling reference value targeting both downlink and uplink terminals is set in advance. Comparing whether the first threshold is greater than or equal to the size;
Determining a transmission direction of the slot based on the comparison result;
Performing scheduling based on the determined transmission direction of the slot; And
And performing communication with a second communication node based on the performed scheduling result.

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