KR20170141587A - Operation method of communication node supporting superposition transmission in cellular communication system - Google Patents

Abstract

Disclosed is a method for operating a communication node supporting superposition transmission in a cellular communication system. An operation method of a base station in a communication system includes the steps of: dividing a primitive transmission block into a plurality of sub-transmission blocks including at least one resource block; setting a transmission power allocation coefficient for each of the plurality of sub-transmission blocks; and transmitting the primitive transmission block mapped onto information indicating the number of resource blocks included in each of the plurality of sub-transmission blocks, information indicating the transmission power allocation coefficient, and a superposition signal including a first data unit of a first terminal and a second data unit of a second terminal. Accordingly, the performance of the communication system can be improved.

Description

Technical Field [0001] The present invention relates to an operation method of a communication node supporting superposition transmission in a cellular communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to transmission / reception techniques in a cellular communication system, and more particularly to methods of operation of a communication node supporting overlap transmission.

Background of the Invention In a cellular communication system, a user equipment can generally transmit and receive data units through a base station. For example, if there is a data unit to be transmitted to the second terminal, the first terminal can generate a message including the data unit to be transmitted to the second terminal, and transmit the generated message to the first base station Lt; / RTI > The first base station can receive the message from the first terminal and confirm that the destination of the received message is the second terminal. The first base station may transmit the message to the second base station to which the second terminal, which is the confirmed destination, belongs. The second base station can receive the message from the first base station and confirm that the destination of the received message is the second terminal. The second base station may transmit the message to the second terminal, which is the identified destination. The second terminal can receive the message from the second base station and obtain the data unit contained in the received message.

Meanwhile, in a cellular communication system, when a first terminal and a second terminal are connected to a first base station, and a first data unit to be transmitted to the first terminal and a second data unit to be transmitted to the second terminal exist in the first base station , The first base station may transmit the first data unit and the second data unit using the same resource (e.g., time and frequency resources). For example, when the channel state between the first base station and the first terminal is different from the channel state between the first base station and the second terminal, the first base station transmits the first data unit and the second data Unit can be transmitted. When such a superposition transmission technique is used, each of the first terminal and the second terminal can acquire the first data unit and the second data unit from the first base station based on the parameters necessary for superposition transmission .

That is, when a superposition transmission technique is used in a cellular communication system, the parameters necessary for superposition transmission must be signaled from the base station to the terminal. However, separate resources (e.g., resources for the control channel) are required for signaling the parameters required for the superposition transmission, thereby reducing the capacity and performance of the cellular communication system.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide operating methods of a base station and a terminal supporting superposition transmission in a cellular communication system.

According to another aspect of the present invention, there is provided a method of operating a base station in a communication system, the method comprising: transmitting a source transport block used for communication in the communication system to a plurality of sub- Blocks for each of the plurality of sub-transport blocks, setting transmission power allocation coefficients for each of the plurality of sub-transport blocks, and information indicating the number of resource blocks included in each of the plurality of sub- Transmitting the original transport block to which the superposition signal is mapped including information indicating a power allocation coefficient, a first data unit of the first terminal and a second data unit of the second terminal, And the second data unit are mapped to the same resources in the original transport block.

Herein, all the resource blocks included in the original transport block can be transmitted based on the same MCS level.

Here, the plurality of sub-transport blocks may be set based on a first channel state between the base station and the first terminal and a second channel state between the base station and the second terminal.

Information indicating the number of resource blocks included in each of the plurality of sub-transmission blocks and information indicating the transmission power allocation coefficient may be included in the DCI of the superposition signal.

Wherein the first data unit may be transmitted using a power based on a first transmit power allocation coefficient set for the first terminal and the second data unit may be transmitted using a second transmit power allocation Coefficient, and the first transmission power allocation coefficient may be different from the second transmission power allocation coefficient.

Herein, the transmission power allocation coefficient may be indicated by a reference signal mapped to the original transport block, and a resource used for transmission of the reference signal may be dynamically set based on a change of a channel state in a frequency domain have.

Here, the first reference signal for the first terminal may be set to be orthogonal to the second reference signal for the second terminal, and the first reference signal may be a first transmission power allocation coefficient set for the first terminal And the second reference signal may be transmitted using a power based on a second transmit power allocation coefficient set for the second terminal, And may be different from the second transmission power allocation coefficient.

Herein, when the information indicating the transmission power allocation coefficient indicates a first transmission power allocation coefficient for a first sub-transmission block among the plurality of sub-transmission blocks, the superposition signal is transmitted to the plurality of sub- And information indicating the increase / decrease amount of the transmission power allocation coefficient for the remaining sub-transmission blocks excluding the first sub-transmission block among the blocks.

According to another aspect of the present invention, there is provided a method of operating a first terminal in a communication system, the method comprising the steps of: receiving a plurality of sub-blocks including at least one resource block - information indicating the number of resource blocks included in each of the plurality of sub-transport blocks, information indicating the transmit power allocation coefficient, information indicating a first data unit of the first terminal and a second data unit of the second terminal, Receiving, from the base station, the original transport block to which a superimposing signal including a second data unit of the terminal is mapped, determining a transmission power of each of the plurality of sub-transport blocks based on information included in the source transport block And determining a channel matrix between the first terminal and the base station and a channel matrix between the first terminal and the base station, Using the power allocation coefficient comprises the step of decoding the first data unit from the superposition signal, the first data unit and the second data units are mapped to the same resource block at the transmission source.

Herein, all the resource blocks included in the original transport block can be transmitted based on the same MCS level.

Information indicating the number of resource blocks included in each of the plurality of sub-transmission blocks and information indicating the transmission power allocation coefficient may be included in the DCI of the superposition signal.

Wherein the first data unit may be transmitted using a power based on a first transmit power allocation coefficient set for the first terminal and the second data unit may be transmitted using a second transmit power allocation Coefficient, and the first transmission power allocation coefficient may be different from the second transmission power allocation coefficient.

Herein, the transmission power allocation coefficient may be indicated by a reference signal mapped to the original transport block, and a resource used for transmission of the reference signal may be dynamically set based on a change of a channel state in a frequency domain have.

Here, the first reference signal for the first terminal may be set to be orthogonal to the second reference signal for the second terminal, and the first reference signal may be a first transmission power allocation coefficient set for the first terminal And the second reference signal may be transmitted using a power based on a second transmit power allocation coefficient set for the second terminal, And may be different from the second transmission power allocation coefficient.

Herein, when the information indicating the transmission power allocation coefficient indicates a first transmission power allocation coefficient for a first sub-transmission block among the plurality of sub-transmission blocks, the superposition signal is transmitted to the plurality of sub- And information indicating the increase / decrease amount of the transmission power allocation coefficient for the remaining sub-transmission blocks excluding the first sub-transmission block among the blocks.

To achieve the above object, in a communication system according to a third aspect of the present invention, a first terminal includes a processor and a memory including at least one instruction executed by the processor, Wherein the source transport block is divided into a plurality of sub-transport blocks including at least one resource block, the at least one instruction indicating the number of resource blocks included in each of the plurality of sub- From the base station, the original transport block to which the superposition signal including the first data unit of the first terminal and the second data unit of the second terminal is mapped, the information indicating the transmission power allocation coefficient, The transmission power allocation coefficient of each of the plurality of sub-transmission blocks is checked based on information included in the transmission block, And to decode the first data unit from the superposition signal using a channel matrix between the first terminal and the base station and the transmit power allocation factor of each of the plurality of sub- And the second data unit are mapped to the same resources in the original transport block.

Herein, all the resource blocks included in the original transport block can be transmitted based on the same MCS level.

Information indicating the number of resource blocks included in each of the plurality of sub-transmission blocks and information indicating the transmission power allocation coefficient may be included in the DCI of the superposition signal.

Herein, the transmission power allocation coefficient may be indicated by a reference signal mapped to the original transport block, and a resource used for transmission of the reference signal may be dynamically set based on a change of a channel state in a frequency domain have.

Herein, when the information indicating the transmission power allocation coefficient indicates a first transmission power allocation coefficient for a first sub-transmission block among the plurality of sub-transmission blocks, the superposition signal is transmitted to the plurality of sub- And information indicating the increase / decrease amount of the transmission power allocation coefficient for the remaining sub-transmission blocks excluding the first sub-transmission block among the blocks.

In accordance with the present invention, parameters (e.g., transmission block size, sub-transport block size, transmit power allocation factor, transmit power allocation factor increase / decrease amount, etc.) required for superposition transmissions in a cellular communication system may include system information, DCI downlink control information, and a reference signal. For example, the information indicating the transport block size and the sub-transport block size may be signaled via system information or DCI, and may include information indicating the increase or decrease in the transmit power allocation factor Information) may be signaled via DCI or a reference signal. Here, the transport block size may be set such that the same modulation and coding scheme (MCS) level is used in the corresponding transport block, and the sub-transport block size may be set such that the same transmit power allocation coefficient is used in the corresponding sub- have.

Thus, since the same MCS level is used in the transport block, the complexity of the decoding operation of the data unit can be reduced. Also, since the same MCS level is used in the transport block and the control information can be signaled using one DCI, the resources used for transmission of the necessary parameters for the overlap transmission can be reduced. As a result, the capacity and performance of the cellular communication system can be improved.

1 is a conceptual diagram showing a first embodiment of a cellular communication system.
2 is a block diagram showing a first embodiment of a communication node constituting a cellular communication system;
3 is a conceptual diagram showing a first embodiment of a type 1 frame.
4 is a conceptual diagram showing a first embodiment of a Type 2 frame.
5 is a conceptual diagram showing a first embodiment of a resource grid of slots included in a subframe.
6 is a block diagram illustrating a first embodiment of a downlink subframe in a cellular communication system.
7 is a conceptual diagram showing a first embodiment of a reference signal pattern in a cellular communication system.
8 is a conceptual diagram showing a second embodiment of a reference signal pattern in a cellular communication system.
9 is a flow chart illustrating a method of operation of a communication node in a cellular communication system.
10 is a conceptual diagram showing a first embodiment of a transmission block in a cellular communication system.
11 is a conceptual diagram showing a second embodiment of a transmission block in a cellular communication system.
12 is a conceptual diagram showing a third embodiment of a reference signal pattern in a cellular communication system.
13 is a conceptual diagram showing a fourth embodiment of a reference signal pattern in a cellular communication system.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. 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 another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

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

1, a cellular communication system may include a base station 100, terminals 110 and 120, and the like. Here, the cellular communication system 100 may be referred to as a "cellular communication network ". Each of the base station 100 and the terminals 110 and 120 included in the cellular communication system can support at least one communication protocol. For example, the base station 100 and the terminals 110 and 120 may each include a communication protocol based on a code division multiple access (CDMA), a communication protocol based on a wideband CDMA (WCDMA), a communication protocol based on a time division multiple access , A frequency division multiple access (FDMA) based communication protocol, an orthogonal frequency division multiplexing (OFDM) based communication protocol, an orthogonal frequency division multiple access (OFDMA) based communication protocol, a single carrier (FD) A non-orthogonal multiple access (NOMA) based communication protocol, and a space division multiple access (SDMA) based communication protocol. Each of the base station 100 and the terminals 110 and 120 may have the following structure.

2 is a block diagram showing a first embodiment of a communication node constituting a cellular communication system;

2, the communication node 200 may be the base station 100, the terminals 110 and 120 shown in FIG. The communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to the network to perform communication. 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 component included in the communication node 200 may be connected by a bus 270 and communicate with each other.

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 on which methods in accordance with embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be constituted of at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may comprise at least one of read-only memory (ROM) and random access memory (RAM).

Referring again to FIG. 1, the base station 100 may form a macro cell or a small cell. The first terminal 110 and the second terminal 120 may belong to the cell coverage of the base station 100 and may be connected to the base station 100. [ For example, each of the first terminal 110 and the second terminal 120 may transmit an uplink data unit to the base station 100. The base station 100 may receive an uplink data unit from each of the first terminal 110 and the second terminal 120 and may transmit the received uplink data unit to a core network . In addition, the base station 100 may receive the downlink data unit from the core network and may transmit the received downlink data unit to the first terminal 110 and the second terminal 120, respectively. Each of the first terminal 110 and the second terminal 120 may receive a downlink data unit from the base station 100. [ The core network may include a serving gateway (S-GW), a packet data network (P-GW), a mobility management entity (MME), and the like.

Each of the base station 100 and the terminals 110 and 120 may be a 4G communication technology (e.g., LTE (Long Term Evolution), LTE-A (advanced), etc.) defined in 3GPP (3rd generation partnership project) 5G communication technology (e.g., mmWave (millimeter wave) based communication technology, etc.). For example, the base station 100 can support OFDMA-based downlink transmission and support SC-FDMA based uplink transmission. In addition, the base station 100 may transmit multiple input multiple output (MIMO) (e.g., single user (SU) -MIMO, multi user (MU) -MIMO, massive MIMO, , Carrier aggregation transmission, transmission in an unlicensed band (e.g., licensed assisted access (LAA) communication), device to device (D2D) communication (e.g., ProSe proximity services, and sidelink communications), and NOMA communications. Herein, each of the first terminal 110 and the second terminal 120 can perform an operation corresponding to the base station 100 and an operation supported by the base station 100. [

Meanwhile, in a cellular communication system, the base station 100 and the terminals 110 and 120 may transmit and receive signals using superposition transmission techniques (e.g., NOMA technology). For example, when a first downlink signal (e.g., a downlink data unit) to be transmitted to the first terminal 110 is S ₁ and a second downlink signal (downlink data unit) to be transmitted to the second terminal 110, Is S ₂ , the base station 100 can generate the superposition coding signal x based on the following Equation (1).

In Equation (1), x may be a superposition coded signal,? ₁ may be a transmit power allocation coefficient for S ₁ , and? ₂ may be a transmit power allocation coefficient for S ₂ . The base station 100 may transmit the superposition coding signal x. The first terminal 110 can receive the superposition coding signal from the base station 100 and the superposition coding signal received from the first terminal 110 (hereinafter referred to as the "first reception signal" 2 < / RTI >

In Equation (2), y ₁ may be a first received signal at the first terminal 110, and h ₁ and n ₁ may be a channel matrix at the first channel between the base station 100 and the first terminal 110, May be a noise vector. For example, h ₁ may indicate the state of the first channel. The second terminal 120 may receive the superposition coding signal from the base station 100 and the superposition coding signal (hereinafter referred to as the "second reception signal" Can be expressed as Equation (3).

In Equation (3), y ₂ may be the second received signal at the second terminal 120, and h ₂ and n ₂ may be the channel matrix and the noise vector at the second channel between the base station 100 and the second terminal 120 . For example, h ₂ may indicate the state of the second channel.

Meanwhile, Equation (4) can indicate that the state of the first channel is worse than the state of the second channel when the relation between h ₁ and h ₂ is expressed by Equation (4) below. In this case, the base station 100 may allocate a relatively large power to a terminal having a poor channel state (e.g., the first terminal 110) in order to maintain the reliability of a transmission signal.

For example, the transmit power allocation coefficient may be set based on Equation (5) below.

을 잡음으로 간주할 수 있다.When the first reception signal y ₁ is received from the base station 100, the first terminal 110 decodes the first reception signal y ₁ using h ₁ and? ₁ to generate a first downlink signal y ₁ S ₁ ). Here, the first terminal 110 may receive the first received signal y ₁ ,

Can be regarded as noise.

을 제거할 수 있다. 그 후에, 제2 단말(120)은 h₂와 α₂를 사용함으로써 제2 수신 신호(y₂)로부터 제2 하향링크 신호(S₂)를 획득할 수 있다. 따라서, 제2 하향링크 신호(S₂)의 복호화 동작에서 제1 하향링크 신호(S₁)에 의한 간섭이 존재하지 않을 수 있다. 제1 수신 신호(y₁)의 복호화 동작을 위해 제1 단말(110)은 h₁과 α₁을 알고 있어야 하고, 제2 수신 신호(y₂)의 복호화 동작을 위해 제2 단말(120)은 h₂, α₁ 및 α₂를 알고 있어야 한다.When the second reception signal y ₂ is received from the base station 100, the second terminal 120 decodes the second reception signal y ₂ using h ₂ and? ₁ to generate the first downlink signal y ₂ S ₁ ) from the second received signal y ₂ using the first downlink signal S ₁ ,

Can be removed. Thereafter, the second terminal 120 may obtain the second downlink signal S ₂ from the second received signal y ₂ by using h ₂ and α ₂ . Thus, the second may not be the interference of the first downlink signal (S ₁₎ present in the decoding operation of the downlink signal (S _2). The first terminal 110 must know h ₁ and α ₁ in order to decode the first received signal y ₁ and the second terminal 120 must decode the second received signal y ₂ , h ₂ , α ₁ and α ₂ .

Meanwhile, an AMC (adaptive modulation and coding) technique, a scheduling technique, and the like can be used for improving the data rate of a data unit in a cellular communication system. When AMC technology is used, the base station can adjust the modulation and coding scheme (MCS) level according to the channel condition between the base station and the terminal to maintain the target reception error rate. For example, if the channel condition is bad, the base station can lower the MCS level so that the actual reception error rate at the terminal is reduced to the target reception error rate. If the channel condition is good, the base station can increase the MCS level so that the actual reception error rate at the terminal is increased to the target reception error rate. Thus, when the AMC technique is used, the actual receive error rate at the terminal can be maintained at the target receive error rate through adjustment of the MCS level, and the maximum data rate of the data unit can be provided while the actual receive error rate is maintained at the target receive error rate .

When a scheduling technique is used, the BS may selectively allocate resources (e.g., time and frequency resources) to the UE in consideration of channel conditions of the UE, quality of service, and the like. Here, the scheduling technique may be a Greedy algorithm-based scheduling technique, a PF (proportional fairness) scheduling technique, or the like.

When the AMC technique, the scheduling technique, or the like is used in a cellular communication system, the BS downwards the AMC information (e.g., MCS level information) and the scheduling information (e.g., time and frequency resource information allocated to the UE) To the terminal through the control channel of the link sub-frame. The AMC information, the scheduling information, and the like may be transmitted through the downlink control information (DCI), and the DCI format 1 may include the information elements described in Table 1 below.

On the other hand, the frame structure used in the cellular communication system may be as follows.

3 is a conceptual diagram showing a first embodiment of a type 1 frame.

Referring to FIG. 3, a radio frame 300 may include 10 subframes, and a subframe may include 2 slots. Thus, the radio frame 600 may include 20 slots (e.g., slot # 0, slot # 1, slot # 2, slot # 3, ..., slot # 18, slot # 19). The length (T _f ) of the radio frame 300 may be 10 ms. The subframe length may be 1 ms. The slot length (T _slot ) may be 0.5 ms. Where T _s can be 1 / 30,720,000s.

The slot may be composed of a plurality of OFDM symbols in the time domain and may be composed of a plurality of resource blocks (RBs) in the frequency domain. The resource block may be composed of a plurality of subcarriers in the frequency domain. The number of OFDM symbols constituting the slot may be changed according to the configuration of the CP (cyclic prefix). CP can be classified into a normal CP and an extended CP. If a normal CP is used, the slot may be composed of 7 OFDM symbols, in which case the subframe may be composed of 14 OFDM symbols. If an extended CP is used, the slot may be composed of six OFDM symbols, in which case the subframe may be composed of twelve OFDM symbols.

4 is a conceptual diagram showing a first embodiment of a Type 2 frame.

Referring to FIG. 4, a radio frame 400 may include two half frames, and a half frame may include five subframes. Thus, the radio frame 400 may include 10 subframes. The length (T _f ) of the radio frame 400 may be 10 ms. The length of the half frame may be 5 ms. The subframe length may be 1 ms. Where T _s can be 1 / 30,720,000s.

The radio frame 400 may include a downlink subframe, an uplink subframe, and a special subframe. Each of the DL subframe and the UL subframe may include two slots. The slot length (T _slot ) may be 0.5 ms. Of the subframes included in the radio frame 400, each of the subframe # 1 and the subframe # 6 may be a special subframe. The special subframe may include a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS).

The downlink pilot time slot can be regarded as a downlink interval and can be used for cell search, time and frequency synchronization acquisition of the terminal, and the like. The guard interval can be used to solve the interference problem of the uplink data transmission caused by the downlink data reception delay. In addition, the guard interval may include a time required for switching from the downlink data reception operation to the uplink data transmission operation. The uplink pilot time slot may be used for uplink channel estimation, time and frequency synchronization acquisition, and the like.

The lengths of each of the downlink pilot time slot, the guard interval, and the uplink pilot time slot included in the special subframe can be variably adjusted as needed. In addition, the number and position of each of the downlink subframe, the uplink subframe, and the special subframe included in the radio frame 400 may be changed as needed.

5 is a conceptual diagram showing a first embodiment of a resource grid of slots included in a subframe.

Referring to FIG. 5, a resource block of a slot included in a downlink subframe or an uplink subframe may be composed of 7 OFDM symbols in a time domain when a normal CP is used, and 12 subframes Carriers. Each of the seven OFDM symbols may be referred to as symbol # 0, symbol # 1, symbol # 2, symbol # 3, symbol # 4, symbol # 5, symbol # 6 and symbol # 7. Each of the 12 subcarriers includes subcarrier # 0, subcarrier # 1, subcarrier # 2, subcarrier # 3, subcarrier # 4, subcarrier # 5, subcarrier # 6, subcarrier # 7, subcarrier # 8, subcarrier # 9, subcarrier # 10 and subcarrier # 11. In this case, a resource constituted by one OFDM symbol in the time domain and one subcarrier in the frequency domain may be referred to as a "resource element (RE) ".

6 is a block diagram illustrating a first embodiment of a downlink subframe in a cellular communication system.

Referring to FIG. 6, the DL subframe may include a control channel (e.g., physical downlink control channel (PDCCH)), a data channel (e.g., physical downlink shared channel (PDSCH) If a normal CP is used, the downlink subframe may be composed of 14 OFDM symbols (or 14 OFMDA symbols) in the time domain, and the PDCCH of the downlink subframe may be composed of 3 OFDM symbols (Or three OFMDA symbols), and the PDSCH of the downlink subframe may be composed of 11 OFDM symbols (or 11 OFMDA symbols) in the time domain.

The PDCCH can be distributed over the entire system band supported by the cellular communication system, and the PDSCH can be transmitted on a resource block basis. Here, the resource block may be composed of 7 OFDM symbols (or 7 OFMDA symbols) in the time domain and 12 subcarriers in the frequency domain. The number of subcarriers included in the resource block may vary depending on the size of the system band supported by the cellular communication system.

The base station can transmit control information (e.g., AMC information, scheduling information) and data units to the UE on a downlink sub-frame basis. For example, the base station may transmit control information over the PDCCH and may transmit the data unit via the PDSCH. The UE can acquire the control information by decoding the PDCCH and can acquire the data unit by decoding the PDSCH based on the obtained control information. On the other hand, if the PDCCH is not decoded or there is no scheduling information for the UE in the decoded PDCCH, the UE can determine that the data unit of the UE does not exist in the DL subframe scheduled by the PDCCH.

In this case, the resource to which the control information is transmitted may be limited to the PDCCH of the downlink subframe, and when MIMO transmission technique, superposition transmission technique, or the like is used in the cellular communication system, much control information is transmitted through the PDCCH (E.g., PDCCH) for transmission of control information may become insufficient. In particular, resources for the transmission of control information in a broadband communication system (e.g., a communication system supporting hundreds of MHz or a few GHz bandwidth) may become even more scarce. In addition, since the reference signal can be transmitted through the DL sub-frame and the control information can not be transmitted in the resource element in which the reference signal is transmitted, resources for transmission of the control information can be insufficient. When a normal CP is used and four antenna ports are used, the reference signal pattern in the subframe may be as follows.

7 is a conceptual diagram showing a first embodiment of a reference signal pattern in a cellular communication system.

Referring to FIG. 7, a common reference signal or a cell-specific reference signal (CRS) is transmitted through a symbol # 0, a symbol # 1, a symbol # 4, a symbol # 7, a symbol # 8 and a symbol # 11 in a time domain of a subframe. And may be transmitted in subcarrier # 1, subcarrier # 4, subcarrier # 7, and subcarrier # 10 in the frequency domain of the subframe. The CRS transmitted through the PDCCH can be used for channel estimation for decoding the control information, and the CRS transmitted through the PDSCH can be used for channel state information acquisition and channel estimation for decoding the data unit. The CRS may be assigned to the same resource element in the resource blocks and the number of resource elements to which the CRS is allocated may be increased as the number of antenna ports increases.

As the number of resource elements to which a CRS is allocated increases with increasing number of antenna ports in a cellular communication system, the number of resource elements used for transmission of control information and data units in a resource block may be reduced. Thus, the data rate of the data unit can be reduced. In order to solve this problem, a reference signal used for channel state information acquisition and channel estimation for decoding a data unit needs to be newly defined. For example, the reference signal pattern in a subframe may be as follows.

8 is a conceptual diagram showing a second embodiment of a reference signal pattern in a cellular communication system.

Referring to FIG. 8, the CRS can be transmitted through the symbols # 0, # 1, # 4, # 7, # 8 and # 11 in the time domain of the subframe, Subcarrier # 1, subcarrier # 4, subcarrier # 7, and subcarrier # 10. A CSI-RS (channel state information-reference signal) may be used for acquiring channel state information, and may not be transmitted for each subframe. For example, the CSI-RS may be transmitted in a 5 msec (millisecond) period. The CSI-RS can be transmitted through symbol # 5, symbol # 6, symbol # 9 and symbol # 10 in the time domain of the subframe and subcarriers # 0 to # 3 and subcarrier # To # 9.

A demodulation-reference signal (DM-RS) may be used for the decoding operation of the data unit received via the PDSCH. The DM-RS transmits the DM-RS # 1 belonging to the group # 1 (for example, code division multiplexing (CDM) group # 1) and the DM-RS # 2 belonging to the group # 2 (for example, . ≪ / RTI > The DM-RS # 1 can be transmitted through the symbol # 5, the symbol # 6, the symbol # 12 and the symbol # 13 in the time domain of the subframe and the subcarriers # 0, May be transmitted through subcarrier # 10. The DM-RS # 2 can be transmitted in the time domain of the subframe through symbol # 5, symbol # 6, symbol # 12 and symbol # 13, and subcarrier # 1, subcarrier # 6 and subcarrier # Can be transmitted through subcarrier # 11.

The DM-RSs (e.g., DM-RS # 1, DM-RS # 2) belonging to each of the groups are multiplexed with reference signals for a plurality of layers based on OCC (orthogonal cover code) . For example, in the transmission of four layers, an OCC of length 2 is applied to two consecutive DM-RSs in the time domain, so that two different DM-RSs can be multiplexed for each group. In the transmission of eight layers, an OCC of length 4 is applied to four DM-RSs consecutive in time domain, so that four different DM-RSs can be multiplexed for each group. In the transmission of one or two layers, only the group # 1 can be used as the DM-RS of each layer, so that the resource elements to which the group # 2 (for example, DM-RS # Lt; / RTI > The layer-by-layer DM-RS may be transmitted using precoding set for the layer. Therefore, the UE can decode the data unit without information of the precoding applied to the Node B, and even when the number of antenna ports increases, the number of resource elements to which the reference signal (for example, DM-RS) May not be increased. However, unnecessary resources may be used for transmission of a reference signal in an environment where a change in channel state is small. Therefore, in order to improve a data rate of a data unit, a method of adaptively allocating a resource for a reference signal .

On the other hand, in a cellular communication system supporting transmission of a wide band (e.g., several hundred MHz or several GHz bandwidth), the base station can allocate frequency bands of several tens MHz to several hundreds of MHz to one terminal. A basic unit of scheduling is a resource block, and a base station can allocate a plurality of consecutive resource blocks to one terminal. That is, when the frequency bandwidth used in the cellular communication system is increased, the base station can allocate a plurality of consecutive resource blocks to one terminal.

When AMC technology is used in a cellular communication system, different MCS levels may be applied to each of a plurality of consecutive resource blocks allocated to one terminal. In this case, a separate DCI may be generated for each resource block to which different MCS levels are applied, and a plurality of DCIs may be transmitted to the UE even though a plurality of consecutive resource blocks are allocated to one UE. Therefore, control information transmitted to the terminal can be increased.

Next, the operation methods of the communication node for reducing the overhead of the control information will be described. In the following description, when a method (e.g., transmission or reception of a signal) to be performed at a first communication node among the communication nodes is described, the corresponding second communication node corresponds to the method performed at the first communication node Method (e.g., receiving or transmitting a signal). That is, when the operation of the terminal is described, it is possible to perform an operation corresponding to the operation of the terminal of the base station corresponding thereto. Conversely, when the operation of the base station is described, the corresponding terminal can perform an operation corresponding to the operation of the base station.

9 is a flow chart illustrating a method of operation of a communication node in a cellular communication system.

9, a cellular communication system may include a base station 100, a first terminal 110, a second terminal 120, and the like, and may support 4G communication technology, 5G communication technology, and the like. For example, a cellular communication system may support a superposition transmission technology (e.g., NOMA technology). Each of the base station 100, the first terminal 110 and the second terminal 120 shown in FIG. 9 is identical to the base station 100, the first terminal 110 and the second terminal 120 shown in FIG. 1 And may be configured the same as the communication node 200 shown in FIG. For example, each of the first terminal 110 and the second terminal 120 may be located within the cell coverage of the base station 100 and may be connected to the base station 100.

The base station 100 may transmit a CSI-RS (e.g., CSI-RS in FIG. 8) through a downlink subframe according to a predetermined period (S900). Each of the first terminal 110 and the second terminal 120 may receive the CSI-RS from the base station 100 and perform a channel measurement operation based on the received CSI-RS. Here, the channel between the base station 100 and the first terminal 110 may be referred to as a "first channel", and the channel between the base station 100 and the second terminal 120 may be referred to as a "second channel" have. The first terminal 110 may transmit the measurement information (e.g., CSI) of the first channel to the base station 100 (S901), and the second terminal 120 may transmit the measurement information of the second channel , CSI) to the base station 100 (S902).

The base station 100 may receive the measurement information of the first channel from the first terminal 110 and the measurement information of the second channel from the second terminal 120. Alternatively, the base station 100 may acquire the measurement information of the first channel by performing the channel measurement operation based on the SRS (sounding reference signal) received from the first terminal 110, And the measurement information of the second channel can be obtained by performing the channel measurement operation based on the received SRS.

The base station 100 may set a transmission block (TB) for superposition transmission using the measurement information of each of the first channel and the second channel (S903). The basic unit of the transport block is a resource block, and the transport block may include a plurality of consecutive resource blocks. The number of resource blocks included in the transport block may be determined based on the channel state. For example, if the channel state change is relatively small in the frequency domain, the transport block may include a relatively large number of resource blocks. On the other hand, if there is a relatively large change in the channel state in the frequency domain, the transport block may include relatively few resource blocks.

Further, in order to prevent a plurality of DCIs from being used by different MCS levels, the same MCS level may be applied to a plurality of consecutive resource blocks included in a transport block. Therefore, the base station 100 can determine the size of the transport block so that the same MCS level is applied to a plurality of consecutive resource blocks included in the transport block, and determine the MCS level applied to the determined transport block. Since the same MCS level is applied to a plurality of consecutive resource blocks included in a transport block, one DCI can be used for a transport block, and therefore, decoding from the side of the UEs 110 and 120 decoding the transport block The complexity of the operation can be reduced.

The size of the transport block may be the system bandwidth supported by the base station 100. In this case, since the base station 100 and the UEs 110 and 120 already know the size of the transport block, the operation of setting the transport block based on the measurement information of the first channel and the second channel may be omitted . However, even if step S903 is omitted, the base station 100 may determine one MCS level applied to a system bandwidth (for example, a transport block) in consideration of measurement information of each of the first channel and the second channel.

The base station can set a sub-transport block for superposition transmission using the measurement information of each of the first channel and the second channel (S904). The transport block may include a plurality of sub-transport blocks, the basic unit of the sub-transport block may be a resource block, and the sub-transport block may include at least one continuous resource block. The same transmission power allocation coefficient may be applied to at least one consecutive resource block included in the sub-transmission block, and different transmission power allocation coefficients may be applied to each sub-transmission block. That is, the BS determines at least one continuous resource block to which the same transmission power allocation coefficient is applied considering the channel state (e.g., change in the channel state) indicated by the measurement information of the first channel and the second channel Determine the size of the sub-transport block to include, and determine the transmit power allocation factor applied to the determined sub-transport block.

For example, the base station 100 may set at least one resource block having a change in channel state within a predetermined range as one sub-transport block, The transmission power allocation coefficient can be set. Therefore, when the channel state change is small in the frequency domain, the number of resource blocks included in the sub-transmission block can be increased, and when there is a large change in the channel state in the frequency domain, The number can be reduced and the change in the channel state within the transmission block can be reflected by using different transmission power allocation coefficients for each sub-transmission block.

For example, a transport block including a plurality of sub-transport blocks may be set as follows.

10 is a conceptual diagram showing a first embodiment of a transmission block in a cellular communication system.

Referring to FIG. 10, the base station 100 includes eight sub-transmission blocks (for example, sub-transmission blocks # 0 to # 7) for superposition transmission between the first terminal 110 and the second terminal 120 ), And determine the MCS level commonly applied to the eight sub-transport blocks included in the transport block 1000. In this case, In addition, the base station 100 may set each of the sub-transport blocks to include one resource block, and may determine a channel state indicated by the measurement information of each of the first channel and the second channel (e.g., Transmission power allocation coefficients for each sub-transport block. If the relationship between the channel matrix in the first channel and the channel matrix in the second channel satisfies Equation (4), the transmit power allocation coefficient may be set based on Table 2 below. α ₁ may be the transmission power allocation coefficient of the first terminal 110, α ₂ may be the transmission power allocation coefficient of the second terminal 120, and "α ₁ + α ₂ " may be one.

11 is a conceptual diagram showing a second embodiment of a transmission block in a cellular communication system.

11, the BS 100 includes four sub-transport blocks (for example, sub-transport blocks # 0 to # 3) for superposition transmission between the first terminal 110 and the second terminal 120 , And may determine the MCS level commonly applied to the four sub-transport blocks included in the transport block 1100. [ In addition, the base station 100 may set each of the sub-transport blocks to include two consecutive resource blocks. For example, sub-transport block # 0 may include resource blocks # 0 and # 1, sub-transport block # 1 may include resource blocks # 2 and # 3, sub- May include resource blocks # 4 and # 5, and sub-transport block # 3 may comprise resource blocks # 6 and # 7.

The base station 100 may set different transmission power allocation coefficients for each of the sub-transmission blocks by reflecting the channel state (e.g., a change in the channel state) indicated by the measurement information of the first channel and the second channel have. If the relationship between the channel matrix in the first channel and the channel matrix in the second channel satisfies Equation (4), the transmit power allocation coefficient may be set based on Table 3 below. α ₁ may be the transmission power allocation coefficient of the first terminal 110, α ₂ may be the transmission power allocation coefficient of the second terminal 120, and "α ₁ + α ₂ " may be one.

Referring back to FIG. 9, the base station 100 may set a DCI including parameters (hereinafter referred to as "overlap transmission parameters") necessary for superposition transmission (S905). The superposition transmission parameters include at least one of information indicating the size of the transmission block, information indicating the size of the sub-transmission block, information indicating the transmission power allocation coefficient, and information indicating the increase / decrease amount of the transmission power allocation coefficient . For example, when the size of the transport block is known in advance in the base station 100 and the UEs 110 and 120 (for example, when the size of the transport block is equal to the system bandwidth supported by the base station 100) , The DCI may include at least one of information indicating the size of the sub-transport block, information indicating the transmission power allocation coefficient, and information indicating the increase / decrease amount of the transmission power allocation coefficient.

The DCI may include information indicating the size of the transport block described in Table 4 below. In this case, a separate DCI including information indicating the size of the transport block is not generated, and information indicating the size of the transport block may be additionally included in the existing DCI (e.g., DCI described in Table 1) have. The number of bits of the information indicating the size of the transport block can be determined according to the system bandwidth and the DCI size can be changed according to the number of bits of the information indicating the size of the transport block. Alternatively, information indicating the size of the transport block may be transmitted via the system information instead of the DCI. For reference, Table 4 below is briefly written for convenience of explanation, and the embodiments are not limited to Table 4. [

For example, based on Table 4, FIG. 10, and FIG. 11, information indicating the size of the transport block can be set to "01" or "001" when the resource block unit contained in the transport block is 4 Quot; 00 "or" 000 "when the resource block unit included in the transport block is 8.

In addition, the DCI may include information indicating the size of the sub-transport block described in Table 5 below. In this case, a separate DCI including information indicating the size of the sub-transport block is not generated, and information indicating the size of the sub-transport block is included in an existing DCI (e.g., DCI shown in Table 1) May be further included. The number of bits of the information indicating the size of the sub-transport block may be determined according to the system bandwidth, and the DCI size may vary according to the number of bits of the information indicating the size of the sub-transport block. Alternatively, information indicating the size of the sub-transport block may be transmitted via the system information instead of the DCI. For reference, Table 5 below is briefly written for convenience of explanation, and the embodiments are not limited to Table 5. [

For example, based on Table 5 and FIG. 10, the information indicating the size of the sub-transport block may be set to "00" or "000". Based on Table 5 and FIG. 11, the information indicating the size of the sub-transport block can be set to "01" or "001" when the resource block unit included in the transport block is 1, Quot; 00 "or" 000 "when the resource block unit is 2.

In addition, the DCI may include information indicating the transmit power allocation coefficients (? ₁ ,? ₂ ) described in Table 6 below. α ₁ and α ₂ The relation between "? ₁ +? ₂ = 1 ", DCI is? ₁ Or < RTI ID = 0.0 _> a2. ≪ / RTI > In this case, a separate DCI including information indicating the transmission power allocation coefficients (alpha ₁ , alpha ₂ ) is not generated, and a transmission power allocation coefficient alpha (alpha) is added to an existing DCI (e.g., DCI shown in Table 1) ₁ ,? ₂ ) may be further included. Here, the number of bits of the information indicating the transmission power allocation coefficients (alpha ₁ , alpha ₂ ) can be determined according to the quantization level, and is determined according to the number of bits of the information indicating the transmission power allocation coefficients (alpha ₁ , alpha ₂ ) Size can vary. For reference, Table 6 below is briefly made for convenience of explanation, and the embodiments are not limited to Table 6. [

For example, based on Table 6 and Fig. 10, the information indicating the transmission power allocation coefficients? ₁ and? _{2 of the} sub-transmission blocks # 0 to # 7 is "000", "001" , "011", "100", "101", "110", and "111" Information indicating the transmission power allocation coefficients? ₁ and? _{2 of the} sub-transmission blocks # 0 to # 3 is "010", "011", "100""

On the other hand, when the transmission power allocation coefficients (? ₁ ,? ₂ ) are set based on Table 6, the information indicating the transmission power allocation coefficients (? ₁ ,? ₂ ) The size of the DCI can be increased. For example, 24 bits (e.g., 3 bits x 8) may be needed to indicate the transmit power allocation coefficients (alpha ₁ , alpha ₂ ) of each of the sub-transport blocks # 0 to # 7 _{shown in} FIG. And 12 bits (for example, 3 bits x 4) may be required to indicate the transmission power allocation coefficients (alpha ₁ , alpha ₂ ) of the sub-transmission blocks # 0 to # 3 shown in FIG.

In order to solve this problem, the DCI allocates the transmission power of the first sub-transport block (for example, sub-transport block # 0 in FIG. 10 and FIG. 11) among the plurality of sub- coefficient (α _1, α ₂₎ of information, a plurality of sub included in the transport block indicating a-transport block (for example, in Figure 10 the sub-transmission blocks from the first sub-transmission blocks to the exception sub- Transmission block # 1 to # 7 in FIG. 11, sub-transmission blocks # 1 to # 3 in FIG. 11). Therefore, in order to indicate the transmission power allocation coefficients (alpha ₁ , alpha ₂ ) of each of the sub-transmission blocks shown in FIG. 10 or 11, six bits (for example, three bits (Table 6) )) May be required.

In addition, not necessarily being separate DCI is generated which includes information indicative of a increased loss of transmission power allocation coefficients (α _1, α ₂₎ information and the transmission power allocation coefficients (α _1, α ₂₎ indicating the existing DCI Information indicating the increase / decrease amount of the transmission power allocation coefficients (alpha ₁ , alpha ₂ ) and information indicating the transmission power allocation coefficients (alpha ₁ , alpha ₂ ) to the DCI (for example, DCI described in Table 1) . Therefore, the overhead of the control information can be reduced. Information indicating the increase / decrease amount of the transmission power allocation coefficients (? ₁ ,? ₂ ) included in the existing DCI can be set based on Table 7 below. Here, information indicating the increased loss of transmission power allocation coefficients (α _1, α ₂₎ number of bits of information indicating the increased weight of the can be determined according to the quantization level, the transmit power allocation coefficients (α _1, α ₂₎ The DCI size may vary depending on the number of bits of the DCI. For reference, Table 7 below is briefly written for convenience of explanation, and the embodiments are not limited to Table 7. [

For example, based on Tables 6, 7 and 10, the information indicating the transmit power allocation coefficients (α ₁ , α ₂ ) of sub-transport block # 0 may be set to "000" Information indicating the increase / decrease amount of the transmission power allocation coefficients (? ₁ ,? ₂ ) for the transmission blocks # 1 to # 7 may be set to "001". Therefore,? ₂ of each of the sub-transport blocks # 0 to # 7 may be "0.2", "0.19", "0.18", "0.17", "0.16", "0.15", "0.14", and " Α ₁ of each of sub-transport blocks # 0 to # 7 may be "0.8", "0.81", "0.82", "0.83", "0.84", "0.85", "0.86", and "0.87".

Based on Table 6, Table 7 and Fig. 11, the information indicating the transmission power allocation coefficient (? ₁ ,? ₂ ) of the sub-transmission block # 0 can be set to "010" The information indicating the increase / decrease amount of the transmission power allocation coefficients (? ₁ ,? ₂ ) for # 7 to # 7 may be set to "110". Therefore,? ₂ of each of the sub-transport blocks # 0 to # 7 may be "0.1", "0.11", "0.12", "0.13", "0.14", "0.15", "0.16", and "0.17" Α ₁ of each of the sub-transport blocks # 0 to # 7 may be "0.9", "0.89", "0.88", "0.87", "0.86", "0.85", "0.84", and "0.83".

On the other hand, if the quantization error for the increased loss of transmission power allocation coefficients (α _1, α ₂₎ can be the quantization error for the generation, transmission power allocation coefficients (α _1, α _2), according to Table 7. In Table 6 Lt; / RTI > The effect of increasing the data rate of the data unit may not be large due to the quantization error. To address this problem, information indicating transmission power allocation coefficients (alpha ₁ , alpha ₂ ) may be transmitted to terminals 110 and 120 via a reference signal (e.g., DM-RS) instead of DCI have. In this case, the base station 100 can set a DM-RS used for transmission of information indicating transmission power allocation coefficients (? ₁ ,? ₂ ).

For example, the DM-RS # 1 for the first terminal 110 can be transmitted using the calculated power based on Equation (6) below. In this case, the first terminal 110 transmits the DM- ( ₁ , ₂ ) based on the received signal strength of the transmission power allocation coefficient ( ₁ , ₂ ). Also, the DM-RS # 2 for the second terminal 120 can be transmitted using the calculated power based on Equation (7) below. In this case, the second terminal 120 transmits the DM- The transmission power allocation coefficient (? ₁ ,? ₂ ) can be estimated based on the received signal strength. The DM-RS # 1 and the DM-RS # 2 used for decoding the superimposed signal can be transmitted so as to be orthogonal to each other.

The DM-RS used for transmission of the information indicating the transmission power allocation coefficients (? ₁ ,? ₂ ) can be set as follows.

12 is a conceptual diagram showing a third embodiment of a reference signal pattern in a cellular communication system.

Referring to FIG. 12, the sub-transmission block may include two consecutive resource blocks in the frequency domain, and may be the same as each of the sub-transmission blocks # 0 to # 3 shown in FIG. Each of the CRS, CSI-RS, DM-RS # 1 and DM-RS # 2 located in the resource elements of the sub-transport block includes CRS, CSI- 2 < / RTI > The number of resource elements allocated for the DM-RS (for example, DM-RS # 1, DM-RS # 2) in the sub-transport block is used for the DM-RS in the sub-transport block of the existing LTE- / RTI > may be two-thirds the number of resource elements allocated.

In the transmission of the four layers, the OCC of length 2 is applied to two DM-RSs consecutive in the time domain, so that two different DM-RSs can be multiplexed for each group. In the transmission of eight layers, an OCC of length 4 is applied to four DM-RSs consecutive in time domain, so that four different DM-RSs can be multiplexed for each group. In this case,? ₁ can be applied to all DM-RS # 1 belonging to group # 1, and? ₂ can be applied to all DM-RS # 2 belonging to group # 2. For example, the transmission of the DM-RS # 1 may be transmitted using the power calculated based on Equation 6, and the transmission of the DM-RS # 2 may be transmitted using the power calculated based on Equation (7) .

Here, each of DM-RS # 1 and DM-RS # 2 may be set to be orthogonal to each other. The DM-RS (for example, DM-RS # 1, DM-RS # 2) is used because the error of the channel estimation becomes small when the change of the channel state is small in the frequency domain (for example, Some of the resource elements set for the data unit may be used for transmission of the data unit. Alternatively, resources for a DM-RS (e.g., DM-RS # 1, DM-RS # 2) may be allocated less in the time domain or frequency domain. On the other hand, the precoding and transmission power allocation coefficients can be used equally in the transmission process of the layer. In this case, the UEs 110 and 120 can decode the data units even when they do not know the precoding and transmission power allocation coefficients used in the base station 100.

13 is a conceptual diagram showing a fourth embodiment of a reference signal pattern in a cellular communication system.

Referring to FIG. 13, the sub-transport block may include two consecutive resource blocks in the frequency domain, and may be the same as each of the sub-transport blocks # 0 to # 3 shown in FIG. Each of the CRS, CSI-RS, DM-RS # 1 and DM-RS # 2 located in the resource elements of the sub-transport block includes CRS, CSI- 2 < / RTI > The number of resource elements allocated for the DM-RS (for example, DM-RS # 1, DM-RS # 2) in the sub-transport block is used for the DM-RS in the sub-transport block of the existing LTE- May be one-half of the number of resource elements allocated.

The number of resource elements used for DM-RS transmission in a sub-transport block may be determined based on a change in channel conditions in the frequency domain. For example, if the channel state change in the sub-transport block shown in FIG. 13 is smaller than the channel state change in the sub-transport block shown in FIG. 12, the DM-RS transmission in the sub- May be less than the number of resource elements used for DM-RS transmission in the sub-transport block shown in FIG.

In the transmission of the four layers, the OCC of length 2 is applied to two DM-RSs consecutive in the time domain, so that two different DM-RSs can be multiplexed for each group. In the transmission of eight layers, an OCC of length 4 is applied to four DM-RSs consecutive in time domain, so that four different DM-RSs can be multiplexed for each group. In this case,? ₁ can be applied to all DM-RS # 1 belonging to group # 1, and? ₂ can be applied to all DM-RS # 2 belonging to group # 2. For example, the transmission of the DM-RS # 1 may be transmitted using the power calculated based on Equation 6, and the transmission of the DM-RS # 2 may be transmitted using the power calculated based on Equation (7) .

Here, each of DM-RS # 1 and DM-RS # 2 may be set to be orthogonal to each other. The DM-RS (for example, DM-RS # 1, DM-RS # 2) is used because the error of the channel estimation becomes small when the change of the channel state is small in the frequency domain (for example, Some of the resource elements set for the data unit may be used for transmission of the data unit. Alternatively, resources for a DM-RS (e.g., DM-RS # 1, DM-RS # 2) may be allocated less in the time domain or frequency domain. On the other hand, the precoding and transmission power allocation coefficients can be used equally in the transmission process of the layer. In this case, the UEs 110 and 120 can decode the data units even when they do not know the precoding and transmission power allocation coefficients used in the base station 100.

9, the base station 100 may transmit control information (e.g., DCI) including superposition transmission parameters, data units (e.g., data transmitted to terminals 110 and 120 in a superposition transmission manner) Unit) and a reference signal to the UEs 110 and 120 (S906). If the control information does not include information indicating the transmit power allocation coefficient, the reference signal (e.g., DM-RS) may be used for transmission of the indicating information. Here, the control information may be transmitted on the PDCCH of the subframe, and the data unit may be transmitted on the PDSCH of the subframe.

The UEs 110 and 120 can receive the subframe from the BS 100 and can confirm the overlapped transmission parameters by decoding the DCI obtained from the PDCCH of the subframe (S907). For example, the UEs 110 and 120 may determine the size of the transport block, the size of the sub-transport block, and the transmit power allocation coefficient (for example, the size of the sub- The transmission power allocation coefficient of each of the plurality of transmission power allocation tables). That is, the UEs 110 and 120 can confirm the size of the transport block set for the superposition transmission based on Table 4, check the size of the sub-transport block set for the superposition transmission based on Table 5, Based on Table 6 and Table 7, it is possible to confirm the transmission power allocation coefficient set for superposition transmission.

On the other hand, when the DCI does not include the information indicating the transmission power allocation coefficient, the UEs 110 and 120 estimate the transmission power allocation coefficient based on the received signal strength of the DM-RS received through the subframe . For example, since the DM-RS # 1 is transmitted based on the transmission power according to Equation (6), the received signal strength of the DM-RS # 1 received at the first terminal 110 is (For example, the received signal strength of the DM-RS # 1 to which? ₁ is not applied). Accordingly, the first terminal 110 can estimate the α ₁ by comparing the received signal strength of the DM-RS # 1 are the received signal strength and α ₁ of the DM-RS # 1 is α ₁ applied not applied, α ₁ And α ₂ Relationship between _{(e.g., "α 1 + α 2 =} 1") can be estimated on the basis of α _2.

을 잡음으로 간주할 수 있다.If the first received signal (y ₁₎ received from the base station 100 in the second equation, h ₁ may be obtained based on the CSI-RS received from the base station (100), α ₁ is the base station 100 The first terminal 110 can decode the first received signal y ₁ using h ₁ and alpha ₁ to obtain the first downlink signal y ₁ by decoding the first received signal y ₁ , S ₁ ) (e.g., a data unit) (S 908). Here, the first terminal 110 may receive the first received signal y ₁ ,

Can be regarded as noise.

Since the DM-RS # 2 is transmitted based on the transmission power according to Equation (7), the received signal strength of the DM-RS # 2 received from the second terminal 120 is equal to the received signal strength of the existing DM- (For example, the received signal strength of the DM-RS # 2 to which? ₂ is not applied). Accordingly, the second terminal 120 by comparing the received signal strength of the DM-RS # 2 that are not subject to the received signal strength and α ₂ of the DM-RS # 2 is α ₂ is applied it is possible to estimate the α _2, α ₁ And α ₂ Relationship between _{(e.g., "α 1 + α 2 =} 1") can be estimated on the basis of α _1.

을 제거할 수 있다. 그 후에, 제2 단말(120)은 h₂와 α₂를 사용함으로써 제2 수신 신호(y₂)로부터 제2 하향링크 신호(S₂)(예를 들어, 데이터 유닛)를 획득할 수 있다(S908).If the second received signal (y ₂₎ received from the base station 100 of Equation 3, h ₂ can be obtained on the basis of the received from the base station 100, CSI-RS, α ₁ and α ₂ is a base station (Or DM-RS) received from the first terminal 100, the second terminal 120 may decode the second received signal y ₂ using h ₂ and alpha ₁ , it is possible to obtain a link signal (S _1), a first down-link signal (S ₁₎ the second received signal (y ₂₎ by using the

Can be removed. Thereafter, the second terminal 120 may obtain the second downlink signal S ₂ (e.g., a data unit) from the second received signal y ₂ by using h ₂ and? ₂ S908).

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

Examples of computer readable media include hardware devices that are specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (20)

A method of operating a base station in a communication system including a base station, a first terminal and a second terminal,
Dividing a source transmission block used for communication in the communication system into a plurality of sub-transport blocks including at least one resource block;
Setting a transmission power allocation coefficient for each of the plurality of sub-transmission blocks; And
Information indicating the number of resource blocks included in each of the plurality of sub-transmission blocks, information indicating the transmission power allocation coefficient, information indicating a first data unit of the first terminal and a second data unit And transmitting the original transport block to which a superposition signal including the superposition signal is mapped,
Wherein the first data unit and the second data unit are mapped to the same resources in the source transport block. The method according to claim 1,
Wherein all resource blocks included in the source transport block are transmitted based on the same modulation and coding scheme (MCS) level. The method according to claim 1,
Wherein the plurality of sub-transport blocks are set based on a first channel state between the base station and the first terminal and a second channel state between the base station and the second terminal. The method according to claim 1,
Wherein information indicating the number of resource blocks included in each of the plurality of sub-transmission blocks and information indicating the transmission power allocation coefficient are included in downlink control information (DCI) of the superposition signal. The method according to claim 1,
Wherein the first data unit is transmitted using power based on a first transmit power allocation coefficient set for the first terminal and the second data unit is transmitted using power based on a second transmit power allocation factor set for the second terminal, And the first transmission power allocation coefficient is different from the second transmission power allocation coefficient. The method according to claim 1,
Wherein the transmission power allocation coefficient is indicated by a reference signal mapped to the original transport block and resources used for transmission of the reference signal are dynamically set based on a change in channel state in a frequency domain. . The method of claim 6,
Wherein a first reference signal for the first terminal is set to be orthogonal to a second reference signal for the second terminal and the first reference signal is set to a power based on a first transmission power allocation coefficient set for the first terminal And the second reference signal is transmitted using a power based on a second transmission power allocation coefficient set for the second terminal, and the first transmission power allocation coefficient is different from the second transmission power allocation coefficient , A method of operating a base station. The method according to claim 1,
When the information indicating the transmission power allocation coefficient indicates a first transmission power allocation coefficient for a first sub-transmission block among the plurality of sub-transmission blocks, the superposition signal is transmitted to the plurality of sub- Further comprising information indicating an increase / decrease amount of a transmission power allocation coefficient for the remaining sub-transmission blocks excluding the first sub-transmission block. A method of operating a first terminal in a communication system including a base station, a first terminal and a second terminal,
A source transmission block used for communication in the communication system is divided into a plurality of sub-transmission blocks including at least one resource block,
Information indicating the number of resource blocks included in each of the plurality of sub-transmission blocks, information indicating the transmission power allocation coefficient, information indicating a first data unit of the first terminal and a second data unit Receiving, from the base station, the original transport block to which a superposition signal is mapped;
Checking transmission power allocation coefficients of each of the plurality of sub-transport blocks based on information included in the source transport block; And
Decoding the first data unit from the superimposed signal using a channel matrix between the first terminal and the base station and the transmit power allocation coefficient of each of the plurality of sub-transmit blocks,
Wherein the first data unit and the second data unit are mapped to the same resources in the source transport block. The method of claim 9,
Wherein all resource blocks included in the source transport block are transmitted based on a same modulation and coding scheme (MCS) level. The method of claim 9,
Wherein information indicating the number of resource blocks included in each of the plurality of sub-transport blocks and information indicating the transmission power allocation coefficient are included in downlink control information (DCI) of the superposition signal, Way. The method of claim 9,
Wherein the first data unit is transmitted using power based on a first transmit power allocation coefficient set for the first terminal and the second data unit is transmitted using power based on a second transmit power allocation factor set for the second terminal, And the first transmission power allocation coefficient is different from the second transmission power allocation coefficient. The method of claim 9,
Wherein the transmission power allocation coefficient is dictated by a reference signal mapped to the source transport block and a resource used for transmission of the reference signal is dynamically set based on a change in a channel state in a frequency domain, How it works. 14. The method of claim 13,
Wherein a first reference signal for the first terminal is set to be orthogonal to a second reference signal for the second terminal and the first reference signal is set to a power based on a first transmission power allocation coefficient set for the first terminal And the second reference signal is transmitted using a power based on a second transmission power allocation coefficient set for the second terminal, and the first transmission power allocation coefficient is different from the second transmission power allocation coefficient , And a method of operating the first terminal. The method of claim 9,
When the information indicating the transmission power allocation coefficient indicates a first transmission power allocation coefficient for a first sub-transmission block among the plurality of sub-transmission blocks, the superposition signal is transmitted to the plurality of sub- Further comprising information indicating an increase / decrease amount of a transmission power allocation coefficient for the remaining sub-transmission blocks excluding the first sub-transmission block. In a communication system including a base station, a first terminal and a second terminal,
A processor; And
A memory including at least one instruction executed by the processor,
A source transmission block used for communication in the communication system is divided into a plurality of sub-transmission blocks including at least one resource block,
Wherein the at least one instruction comprises:
Information indicating the number of resource blocks included in each of the plurality of sub-transmission blocks, information indicating the transmission power allocation coefficient, information indicating a first data unit of the first terminal and a second data unit From the base station, the primitive transport block to which a superposition signal including the primitive signal is mapped;
Identify the transmit power allocation factor of each of the plurality of sub-transport blocks based on information included in the source transport block; And
And to decode the first data unit from the superposition signal using a channel matrix between the first terminal and the base station and the transmit power allocation coefficient of each of the plurality of sub- Wherein the data unit and the second data unit are mapped to the same resources in the original transport block. 18. The method of claim 16,
Wherein all resource blocks included in the source transport block are transmitted based on a same modulation and coding scheme (MCS) level. 18. The method of claim 16,
Wherein information indicating the number of resource blocks included in each of the plurality of sub-transmission blocks and information indicating the transmission power allocation coefficient are included in downlink control information (DCI) of the superposition signal. 18. The method of claim 16,
Wherein the transmission power allocation coefficient is dictated by a reference signal mapped to the original transport block and resources used for transmission of the reference signal are dynamically set based on a change in channel state in a frequency domain. 18. The method of claim 16,
When the information indicating the transmission power allocation coefficient indicates a first transmission power allocation coefficient for a first sub-transmission block among the plurality of sub-transmission blocks, the superposition signal is transmitted to the plurality of sub- Further comprising information indicating an increase / decrease amount of a transmission power allocation coefficient for the remaining sub-transmission blocks excluding the first sub-transmission block.

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