JP6476135B2 - Power control and multiplexing method and apparatus for performing D2D communication in a wireless cellular communication system - Google Patents

Description

  The present invention relates to a general wireless mobile communication system, and in particular, a terminal operation including a transmission power control procedure and a multiplexing procedure of a terminal in a state where D2D communication technology and wireless cellular communication technology are mixedly used, and a base corresponding thereto. The present invention relates to station operation and these devices.

  As the types of services using wireless mobile communication systems become large and diverse, there is a need for new technologies for more efficiently supporting newly emerging services, thereby enabling new methods within wireless mobile communication systems. And technology has been developed and studied.

  Terminal to Device (D2D) communication is a new technology that has emerged as a solution for new services, and D2D communication is basically a direct communication between other terminals around the terminal. It is a technology that makes it possible. If the D2D communication technology is used, the terminal can discover what kind of terminal is around and can perform direct communication with the terminal that needs communication.

  If D2D can perform direct communication, it will use less radio resources compared to communication using a base station using an existing radio network, which is large in terms of radio resource efficiency. Have a merit. In addition, since a method capable of discovering terminals around the terminal is supported, it becomes possible to provide necessary information to the terminal directly desired by the terminal, and an advertisement service, a social network service (Social Networking Service: below) (SNS) and the like can be greatly improved in efficiency.

  Currently, the Long Term Evolution (Advanced) (hereinafter referred to as LTE-A) system also requires support for D2D technology, and technical discussions are in progress.

  FIG. 1 is a diagram illustrating a scenario in which D2D communication is supported in a cellular system.

  The base station 101 manages the terminal 103 and the terminal 104 in the cell 102 managed by the base station. The terminal 103 performs cellular communication using the link 106 between the base station 101 and the terminal-base station, and the terminal 104 uses the link 107 between the base station 101 and the terminal-base station. Communication begins. When D2 communication is possible between the terminal 103 and the terminal 104, it is possible to exchange information directly with each other using the D2D link 105 without passing through the base station 101.

  A terminal-to-terminal (Device to Device, hereinafter referred to as D2D) technology using a cellular radio mobile communication system such as an LTE-A system basically does not cause maximum damage to a terminal using an existing cellular system. Assume that it runs in the direction. For this purpose, a resource that does not overlap with a radio resource used by a cellular terminal (in the present invention, a cellular terminal refers to a terminal that performs existing terminal-to-base station communication rather than D2D communication) is used for D2D communication. It is also possible to consider that the resources used by the cellular terminals are used by the D2D terminals in the same way but do not give the maximum interference to each other.

  There is a frequency division duplexing (hereinafter referred to as FDD) as a reverse and forward duplexing method used by the LTE or LTE-A system.

  In the FDD, the forward direction and the reverse direction are distinguished by using other frequency resources. When D2D communication is used separately from existing cellular communication resources in a system using FDD, generally, a method of using a reverse frequency resource with D2D among the forward and reverse resources tends to be more prioritized. is there. This is because, in the FDD system, more types of signals are multiplexed in the forward frequency resource than in the reverse frequency resource, and it is difficult to separately allocate resources for D2D communication use as compared with the reverse resource.

  Also, in an FDD system that considers only existing cellular terminals, due to the characteristics of communication services, the forward traffic tends to be larger than the reverse direction, and the overhead transmitted in the forward direction is higher than the reverse direction. Therefore, the frequency usage burden for forward resources is generally larger than the frequency usage burden for backward resources.

  Therefore, if the forward resource is allocated and used for D2D communication, the burden on the forward resource becomes larger, and it becomes difficult to balance the use of forward and reverse frequency resources.

  Assuming that D2D communication is performed using reverse resources in a communication system using FDD, the problems caused by using the forward resources in the D2D technology described above can be solved. However, applying the D2D communication technology using reverse resources does not solve all the problems. As an example, a reverse resource used in the LTE system can be assigned a resource of an arbitrary size at both ends of the entire band in order to transmit control information for an existing cellular terminal.

  The control information transmitted in the reverse direction includes forward link channel state information (Channel Quality Information: hereinafter referred to as CQI), forward automatic communication complex automatic retransmission (hereinafter referred to as HARQ) technology. ACK / NACK information that is response information, scheduling request information for transmitting reverse direction information, and the like may be included.

  The control information is transmitted from an arbitrary terminal in the reverse direction, that is, to the base station. When only the cellular terminal communicates with the reverse resource, the control information can be transmitted even when the D2D terminal communicates between the terminals. That is, there may occur a case where a plurality of D2D terminals communicate with each other at the same time in the same cell (for example, in the same subframe in LTE), and the cellular terminal transmits control information to the base station. it can. In the above case, it is possible to assume the same case where the frequency resource used by the cellular terminal for transmitting control information and the frequency resource used by the D2D terminal for communication between terminals are different from each other.

  FIG. 2 is a diagram illustrating a scenario in which a cellular terminal and a D2D terminal in the same cell simultaneously transmit and receive signals with a base station using reverse resources in the same subframe.

  The base station 201 has a cell, and the terminals 203, 205, and 206 are located in the cell. The terminal 203 is transmitting reverse direction control information with the cellular terminal using the reverse direction resource 204. The terminal 205 is performing D2D communication with the terminal 206, and the terminal 205 can transmit information using the D2D link 207 at the terminal 206. At this time, the terminal 203 appropriately sets transmission power for information transmission so that the base station 201 has appropriate reception power when the reverse direction control information is received. In addition, the terminal 205 appropriately sets transmission power for information transmission so that the terminal 260 has appropriate reception power when receiving the D2D transmission.

  In this case, when the distance between the terminal 205 and the terminal 206 is increased, the terminal 205 may perform D2D transmission by setting a large transmission power so that transmission to the terminal 206 is properly performed. At this time, when the terminal 205 is positioned so as to be in close contact with the base station 201, the D2D transmission transmitted from the terminal 205 to the terminal 206 can be received by the base station 201 with very large reception power.

  At this time, if the received power received by the base station 201 from the terminal 205 (see 208) is greater than a certain value compared to the signal transmitted by the cellular terminal 203 in the reverse direction, the reception sensitivity is insufficient in receiving the signal ( There is a possibility that the base station 201 may not be able to receive the reverse direction control information transmitted by the terminal 203 due to the occurrence of a “destaining” phenomenon.

  When the cellular terminal and the D2D terminal included in one base station transmit simultaneously using the reverse frequency resource, the cellular station receives a difference in strength between received signals from the cellular terminal and the D2D terminal. Described the problem that information sent from the terminal cannot be received. In the present invention, it is intended to describe the power control procedure of the D2D terminal and related operations of the base station and the terminal to solve the problem due to the lack of reception sensitivity in the above-described scenario.

  The present invention has been devised to solve the above-described problems. According to one aspect of the present invention, there is a problem in that reception sensitivity decreases between a terminal using a D2D technology and a cellular terminal in a mobile communication system. D2D channel power control procedure required for simultaneous communication without causing occurrence, procedure for one terminal to simultaneously transmit D2D data and cellular data, and operation method of base station and terminal for supporting the procedure And an apparatus.

  According to an aspect of the present invention, in a wireless communication system, a method for power control of a terminal for D2D communication includes: receiving a power control related information for D2D communication from a base station; Determining the transmission power of the terminal based on the available power and the received power control related information for the D2D communication, and transmitting data according to the determined transmission power. Features.

   According to another aspect of the present invention, in the wireless communication system of the present invention, a terminal that controls power for D2D communication includes: a transmission / reception unit that transmits / receives a signal to / from a terminal or a base station; and the D2D from the base station. Receiving power control related information for communication, determining transmission power of the terminal based on the maximum usable power of the terminal and the received power control related information for D2D communication, and determining the determined transmission power And a control unit that controls to transmit data.

  According to another aspect of the present invention, in a wireless communication system, a terminal power control method for D2D communication includes receiving transmission related information for the D2D communication from a base station, and based on the transmission related information. Determining whether a transmission subframe of cellular information to be transmitted to the base station is a subframe allowing D2D communication; and, as a result of the determination, a transmission subframe of cellular information being a subframe allowing D2D communication Determining transmission power using a first offset value included in the transmission-related information; and transmitting the cellular information to the base station according to the determined transmission power. And

  According to another aspect of the present invention, in a wireless communication system, a terminal that controls power for D2D communication includes: a transmission / reception unit that transmits / receives a signal to / from a terminal or a base station; and transmission related to the D2D communication from a base station Information is received, and it is determined whether a transmission subframe of cellular information to be transmitted to the base station based on the transmission related information is a subframe that allows the D2D communication. If the subframe allows the D2D communication, the transmission power is determined using the first offset value included in the transmission related information, and the cellular information is transmitted to the base station using the determined transmission power. And a control unit for controlling as described above.

  According to another aspect of the present invention, in a wireless communication system, a multiplexing method of a terminal for D2D communication includes uplink control including ACK or NACK for whether to receive forward information at an arbitrary time. A step of determining whether transmission of information is necessary; a step of determining whether information included in the uplink control information is ACK or NACK when transmission is necessary; and the determination result, the uplink control information And transmitting the uplink control information to the base station without transmitting information for D2D communication when the information included in the ACK is ACK.

  According to another aspect of the present invention, in a wireless communication system, a terminal that multiplexes cellular information and D2 communication information includes a transmission / reception unit that transmits / receives a signal to / from a terminal or a base station, and forward information at an arbitrary time. It is determined whether transmission of uplink control information including ACK or NACK for whether to receive is necessary, and when transmission is necessary, it is determined whether information included in the uplink control information is ACK or NACK, As a result of the determination, when the information included in the uplink control information is ACK, control is performed such that the uplink control information is transmitted to the base station without transmitting information regarding D2D communication.

It is a communication basic drawing of D2D. It is a reverse frequency resource used by the resource of D2D. 4 is a flowchart illustrating an autonomous cell deactivation process according to an exemplary embodiment of the present invention. 5 is a flowchart illustrating an operation procedure of a small cell performing a network control cell deactivation procedure according to an embodiment of the present invention. It is a block diagram which shows the internal structure of the transmitter apparatus of D2D terminal by one Embodiment of this invention. It is a block diagram which shows the internal structure of the base station apparatus for the power control of D2D terminal by one Embodiment of this invention. 5 is a flowchart illustrating an operation procedure of a terminal according to an embodiment of the present invention. 5 is a flowchart illustrating an operation procedure of a base station according to an embodiment of the present invention. It is a block diagram which shows the internal structure of the terminal by other embodiment of this invention. The block diagram which shows the internal structure of the base station by other embodiment of this invention. 4 is a flowchart illustrating a multiplexing operation procedure of a terminal according to an embodiment of the present invention. 7 is a flowchart illustrating a multiplexing operation procedure of a terminal according to another embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, when it is determined that a specific description of a known function or configuration related in describing the present invention can make the gist of the present invention unnecessary, a detailed description thereof will be omitted. The terms described later are terms defined in consideration of the functions in the present invention, and can be changed according to the intention of the user, the operator or the custom. Therefore, the definition must be taken based on the contents throughout this specification.

  In describing embodiments of the present invention, a wireless communication system based on OFDM, particularly the 3GPP EUTRA standard, is mainly targeted. However, the main gist of the present invention is to provide a similar technical background and channel form. The present invention can be applied to other communication systems with a slight modification without departing from the scope of the present invention, and this can be determined by a person having technical knowledge skilled in the technical field of the present invention. Let's go.

  Hereinafter, base stations or cells may be used interchangeably in the described embodiments of the invention. Further, the D2D communication can be used to include all of a terminal discovery operation for discovering a terminal that is in contact and direct communication in which the terminal and the terminal exchange information directly.

  In the above description, when an FDD system is assumed in a duplexing method to which the present invention is applied, it is described that D2D communication is supported using a reverse frequency resource.

  FIG. 3 is a diagram illustrating resources that can be used for D2D using a reverse resource format currently supported by LTE.

  In FIG. 3, 301 indicates that a plurality of subframes are gathered on the time axis. The subframe means a 10 ms time interval including a large number of symbols as a time unit used in LTE. In the present invention, the subframe used in LTE is given as an example. Can be applied.

  In the present invention, it is assumed that a part of the subframe set 301 is used as a resource for D2D. In FIG. 3, the regular subframes 302 is assigned for cellular communication, and the D2D subframes 303 is assigned for D2D communication.

  Specifically, resource of D2D subframes 303 may include several subframes in the reverse resource for D2D. One subframe includes multiple OFDM (Orthogonal Frequency Division Multiplexing) symbols on the time axis or SC-FDM (Single-Carrier Division Multiplexing) symbols, and includes several subcarriers on the frequency axis.

  As described above, among the subcarriers that can be used on the frequency axis in the LTE reverse resource, as shown by 304 and 305 in FIG. 3, a large number of subcarriers located at both ends are reversely moved. It is used for transmission of control information (in LTE, this means Physical Uplink Control Channel (PUCCH)). As described in the prior art, the reverse control information includes forward link channel state information (Channel Quality Information: hereinafter referred to as CQI), complex automatic retransmission of forward communication (hereinafter referred to as HARQ). ACK / NACK information, which is response information for technology, scheduling request information for transmitting reverse direction information, and the like may be included.

  On the other hand, D2D transmission is possible via a large number of subcarriers 306 located in the middle of the frequency axis excluding both ends of the subframe. At this time, the last OFDM symbol (or SC-FDM symbol) located in each subframe is used for transmitting a sounding reference signal (hereinafter referred to as SRS) necessary for channel estimation in the reverse direction of the UE at the base station. Can be used. Since the transmission period of the SRS changes according to the setting of the base station, there can be subframes including the SRS, and there can also be subframes not including the SRS. In a subframe without SRS, the last symbol 307 can be used in the resource for D2D, and there are cases where a terminal on the nature of D2D has to continue transmission and reception. It is also possible to use the last symbol 307 at the transition time required while changing the operation from the reception to the transmission or changing the operation from the reception to the transmission.

  Based on the reverse resource shown in FIG. 3, the reception sensitivity deficiency (de-sensing) phenomenon can be described with reference to FIG. That is, in a situation where a terminal 205 located near an arbitrary base station 201 transmits using a D2D resource to a terminal 206 far away using the D2D communication channel 207, another cellular terminal 203 uses the PUCCH 204 in the base station 201. If transmission is started, the base station 201 may not be able to accurately receive the PUCCH 204 transmitted by the terminal 203 due to a reception sensitivity lowering phenomenon. This is because there may occur a case where the reception intensity of one or more signals received by one base station 201 is different from a certain value. That is, when the signal 208 transmitted from the terminal 205 reaches the base station 201, a situation in which the reception intensity becomes very large can occur. The present invention presents a method for solving the above situation where a base station cannot receive cellular terminal information through communication of a D2D terminal through the following embodiment.

  First, prior to describing the transmission power control presented in the present invention, a transmission power control method when the transmitter and the receiver generally communicate, particularly when the transmitter is a terminal, will be described. When the terminal transmits an arbitrary channel to the base station, the transmission power to be used can be determined by a smaller value of the following two variables.

1. Maximum usable power of transmitter (terminal) 2. Transmission power that can match the desired received power when the receiver (base station) receives the signal transmitted by the transmitter (terminal).

  Here, the maximum usable power of the transmitter, that is, the terminal, can be a physically usable power limited by the terminal hardware for information transmission by the transmitter, or the base station It can be the maximum power determined by any setting. The receiver, that is, the base station, tries to match the received power of the terminal with a constant value. This is to prevent the reception sensitivity lowering phenomenon when the signals of many terminals are received at the same time, and further facilitate the scheduling for the transmission of the terminals. Therefore, the terminal limits the transmission power in order to match the reception power of the base station.

  Therefore, the transmission power of the terminal can be determined by the two variables, and the transmission power of the terminal can be expressed by the following mathematical formula.

  Tx_Power = min {Max_Tx_Power, f (Rx_Power)} --- (1)

  In the equation (1), Tx_Power is the transmission power of the terminal, Max_Tx_Power is the maximum usable power of the terminal, Rx_Power is the reception power of the base station that receives the transmission signal of the terminal, and the function f (Rx_Power) is the above-mentioned This is the transmission power determined by the terminal when Rx_Power is determined. Although the function f (Rx_Power) can be variously determined using the Rx_Power value, the most representative mathematical formula is as follows.

  f (Rx_Power) = Rx_Power + Prop_loss --- (2)

  In the equation (2), Prop_loss is a path loss due to the distance between the transmitter and the receiver, and is determined not only by the distance between the transmitter / receiver but also by the state where the transmitter / receiver is located, the medium existing between the transmitter / receiver, etc. The The terminal measures the received power of the reference signal transmitted by the base station, and measures the transmission power of the reference signal from the base station, so that the path loss value between the terminal and the base station can be known. The path loss value is a value measured over a long period, and it can be assumed that the reverse and forward path losses are the same. Therefore, the path loss value measured in the forward direction is It can be used for power control of reverse transmission.

  The f (Rx_Power) equation can be defined using various variables in addition to the path loss value. Examples of the variable include the amount of channel resources (for example, the number of PRBs (Physical Resource Blocks) defined in LTE), an arbitrary offset value set in the base station, and other various variables. Can do. The f (Rx_Power) equation can be obtained by adding an arbitrary weight value to each variable and combining them. The weight value can be changed, can be set by a base station, and can correspond to a positive value or a negative value.

  In the following, the present state of solution for reducing the reception sensitivity of the base station through the power control of the D2D terminal will be described through various embodiments.

Embodiment 1: D2D channel power control In this embodiment, a terminal that performs D2D communication uses the D2D link (in the present invention, a link means a radio path through which information is transmitted between a transmitter and a receiver, a radio link, a channel, In the case of transmitting a signal via a radio channel, connection, etc.), when transmitting a signal via an appropriate setting of transmission power for the D2D link, information transmission via the D2D link and the base station A method to support all the solutions to the phenomenon of reduced reception sensitivity is presented.

  An arbitrary base station and a cellular terminal exist, and the cellular terminal transmits arbitrary control information or data information at the base station, and is present in the base station at the same time or the same subframe. In a situation where the terminal is transmitting the D2D channel, the transmission power of the D2D terminal can be determined by one of the following three variables. According to a preferred embodiment of the present invention, the three variables Can be determined by the smallest value of.

1. 1. Maximum usable power of the transmitting D2D terminal (205 in FIG. 2) A transmission power that can match a desired reception power when the signal transmitted by the transmission D2D terminal (205 in FIG. 2) is received by the reception D2D terminal (206 in FIG. 2) 3. The transmission D2D terminal (in FIG. 2) 205), when the base station (201 in FIG. 2) receives the signal transmitted by the base station (201 in FIG. 2), the base station does not cause a reception sensitivity lowering phenomenon in the reception of the signal received from another cellular terminal (203 in FIG. 2). Transmit power

  The maximum usable power of the terminal can be a physically usable power limited by the transmitter hardware for information transmission by the transmitter, or a maximum determined by any setting of the base station Can be electric power. Also, the reason for making an effort to match the D2D channel transmitted by the transmitting D2D terminal so that the receiving D2D terminal can receive the appropriate reception power is to facilitate the scheduling of the transmission of the transmitting D2D terminal. That is. The third variable is arbitrary than a signal received from another cellular terminal while maintaining the reception power of the D2D transmission below a certain level, assuming that the base station receives the D2D transmission transmitted by the transmitting D2D terminal. It becomes a value that does not become larger than the value of. In this case, the third variable prevents a situation in which the reception signal of the D2D terminal is so much larger than the reception signal of the cellular terminal in the base station that the reception sensitivity of the signal of the cellular terminal is lowered. The above contents are expressed as follows.

  Tx_Power = min {Max_Tx_Power, f (Rx_Power_D2D), g (Rx_Power_eNB)} --- (3)

  In Equation (3), Tx_Power is the transmission power of the transmission D2D terminal, Max_Tx_Power is the maximum usable power of the transmission D2D terminal, Rx_Power_D2D is the reception power of the reception D2D terminal that receives the transmission signal of the transmission D2D terminal, and Rx_Power_2NB It can be the received power when the base station receives the transmission signal of the transmission D2D terminal.

  The function f (Rx_Power_D2D) is the transmission power determined by the transmission D2D terminal when the Rx_Power_D2D is determined, and the function g (Rx_Power_eNB) is determined by the transmission D2D terminal when the Rx_Power_2NB is determined The determined transmission power.

  Although the function f (Rx_Power_D2D) can be variously determined using the Rx_Power_D2D value, the most typical mathematical formula is as follows.

  f (Rx_Power_D2D) = Rx_Power_D2D + Prop_loss_D2D --- (4)

  In Formula (4), Prop_loss_D2D is a path loss due to the distance between the transmission D2D terminal and the reception D2D terminal, and not only the distance between the transmission / reception units but also the state where the transmission / reception units are located, the medium existing between the transmission / reception units, etc. Determined by. When the transmitting D2D terminal and the receiving D2D terminal set up the D2D channel, the transmitting D2D terminal knows the path loss through transmission / reception of any promised signal and information sharing for the transmission power of the promised signal.

  The f (Rx_Power_D2D) equation can be defined using various variables in addition to the path loss value. The variable is the amount of channel resources to be transmitted (for example, the number of PRBs (Physical Resource Blocks defined in LTE)), or an arbitrary value set in the base station or between the D2D terminals via the channel setting. Examples include offset values and various other variables. The f (Rx_Power_D2D) equation can be obtained by adding an arbitrary weight value to each variable and combining them. The weight may be changed, may be set by a base station or may be set between D2D terminals via channel setting, and may correspond to a positive value or a negative value.

  The function g (Rx_Power_eNB) can be defined in various ways using the Rx_Power_eNB value. The most representative mathematical formula is as follows.

  g (Rx_Power_eNB) = Rx_Power_eNB + Prop_loss_eNB + Dense_Offset --- (5)

  In the above equation (5), Prop_loss_eNB is a path loss due to the distance between the transmission D2D terminal and the base station, and not only the distance between the transmission D2D terminal and the base station but also the state where the transmission D2D terminal and the base station are located, The transmission D2D terminal measures the reception power of the reference signal transmitted by the base station, measures the transmission power of the reference signal from the base station, and determines the transmission D2D. The path loss value between the terminal and the base station is known.

  The desense offset (Dense_Offset) may be defined as a value that is adjusted so as not to reduce reception sensitivity when the base station receives both the D2D signal and a signal from another cellular terminal. The desense offset (Dense_Offset) can be determined with an arbitrary value in consideration of the performance of the receiver of the base station, and can be set by the base station and notified to the transmission D2D terminal.

  The g (Rx_Power_eNB) equation can be defined using various variables in addition to the path loss value. Examples of the variable include the amount of D2D channel resources to be transmitted (for example, the number of PRB (Physical Resource Block) defined in LTE), an arbitrary offset value set in the base station, and various other variables. Can do. The g (Rx_Power_eNB) equation can take a scheme in which an arbitrary weight is assigned to each variable. The weight value can be changed, can be set by a base station, and can correspond to a positive value or a negative value.

  Hereinafter, an operation flowchart of the terminal and the base station according to the first embodiment of the present invention will be described.

  FIG. 4 is a flowchart illustrating a transmission power control process of the D2D channel transmitted by the D2D terminal.

  FIG. 4 shows a transmitting D2D terminal 401, a receiving D2D terminal 402, and a base station 403. The transmitting D2D terminal 401 and the receiving D2D terminal 402 set D2D (or a channel for D2D communication) in step 404. In step 404, the base station information may be used. For example, D2D transmitting and receiving terminals discover each other, perform scheduling, and in order to actually transmit data, synchronization between each other should be performed. The synchronization signal transmitted by the base station (PSS, SSS) or the like.

  Next, the transmitting D2D terminal 401 receives power control related information from the base station 403 in step 405. The power control related information may include information used when f (Rx_Power_D2D) is determined by the mathematical formula or information used when g (Rx_Power_eNB) is determined. The receiving D2D terminal 402 can also receive power control related information from the base station 403 in step 406. This is because the receiving D2D terminal 402 can also be a transmitting D2D terminal for the D2D channel. The power control related information in step 406 is not necessarily the same as the power control related information in step 405.

  FIG. 4 shows that the base station that provides power control related information to the transmitting D2D terminal 401 and the base station that provides power control related information to the receiving D2D terminal 402 are the same base station 403. Instead, for example, when the base stations to which each D2D terminal belongs are different base stations, they can be different base stations.

  The transmitting D2D terminal 401 and the receiving D2D terminal 402 can then determine the path loss for the D2D channel. The path loss can be determined in advance in step 404. The determination on the path loss may be shared between the transmitting D2D terminal 401 and the receiving D2D terminal 402 via path loss calculation and measurement report by the reference signal transmission in step 407 and the measurement of the reference signal in step 408. The transmission D2D terminal 401 can transmit the D2D channel in step 409 using the following mathematical formula.

  Tx_Power = min {Max_Tx_Power, f (Rx_Power_D2D), g (Rx_Power_eNB)} --- (6)

  FIG. 5 is a block diagram illustrating an internal structure of a transmission D2D terminal according to an embodiment of the present invention.

  The storage unit 501 may store the power control-related setting value received from the base station, that is, information used when determining f (Rx_Power_D2D) or information used when determining g (Rx_Power_eNB). it can.

  The power control related information stored in the storage unit 501 is input to the power control controller 502, and then the power control controller 502 determines the transmission power of the D2D channel using the above formula and transmits the power amplifier to the power amplifier via the control signal 503. Input the transmission power of the D2D channel.

  On the other hand, the D2D channel generator 504 generates a signal for wirelessly transmitting information transmitted via the D2D channel via channel coding, modulation, and the like. The signal is amplified by a power amplifier 505. At this time, the power control controller 502 determines the position to be amplified using the control signal 503. The signal amplified by the power amplifier 505 is transmitted wirelessly via the transmission unit 506.

  In the above description, the power controller 502 and the D2D channel generator 504 are shown separately as separate blocks. However, it is not always necessary to be divided into physically separated hardware as described above, and detailed functional blocks performed by the control unit. It can also be embodied.

  FIG. 6 is a block diagram illustrating an internal structure of a base station apparatus for power control of a D2D terminal according to an embodiment of the present invention.

  The D2D power control related setting value determination unit of the base station determines a power control related setting value necessary when the D2D terminal receives the D2D channel (601). The power control related setting value may include information used when determining f (Rx_Power_D2D). Also, the D2D power control related setting value determining unit of the base station determines a power control related setting value required when the base station receives the D2D channel (602). The power control related setting value may include information used when g (Rx_Power_eNB) is determined.

  The two setting values are signaled to the D2D terminal via the transmission unit 603. The procedure to be signaled is shown in step 405 of FIG. In FIG. 6, the D2D power control related setting value determining unit is divided into two blocks, but is not necessarily divided into hardware physically divided as described above, and is performed by the control unit. It should be noted that it can also be embodied in detailed functional blocks.

Embodiment 2: When there is a D2D channel , in the second embodiment of the present invention described below, the reception of the cellular terminal by the D2D link reception of the D2D terminal located at the position where the base station is in contact In order to solve the sensitivity reduction problem, the cellular terminal presents a new power control method.

  As described above, when the cellular terminal transmits information using the cellular channel in the reverse direction, it has been described that the transmission power is used with a value determined by the following equation.

  Tx_Power = min {Max_Tx_Power, f (Rx_Power)} --- (7)

  In Equation (7), Tx_Power is the transmission power of the terminal, Max_Tx_Power is the maximum usable power of the terminal, Rx_Power is the reception power of the base station that receives the transmission signal of the terminal, and the function f (Rx_Power) is the above-mentioned This is the transmission power determined by the terminal when Rx_Power is determined.

  In the present embodiment, the cellular terminal presents a method for setting transmission power using other mathematical formulas depending on whether or not a D2D terminal exists.

  That is, when there is a D2D terminal near the base station and the base station receives the transmission of the cellular terminal, the cellular terminal is connected to the D2D terminal so as to prevent the reception sensitivity from being lowered by the D2D terminal. In some cases, the method includes adding an additional offset to the transmission power and transmitting with a stronger transmission signal. This embodiment according to the above description can be expressed by the following mathematical formula.

  Tx_Power = min {Max_Tx_Power, f (Rx_Power) + offset_D2D} --- (8)

  In Equation (8), Tx_Power is the transmission power of the terminal, Max_Tx_Power is the maximum usable power of the terminal, Rx_Power is the reception power of the base station that receives the transmission signal of the terminal, and the function f (Rx_Power) is the above-mentioned When Rx_Power is determined, the terminal can become the communication power determined thereby. Finally, offset_D2D, which is a variable, is an offset having another value depending on whether or not there is a D2D terminal that performs simultaneous transmission with the cellular terminal when the cellular terminal transmits arbitrary data information or control information.

  In general, a larger offset_D2D value can be set when there is a D2D terminal that transmits at the same time than when there is not. For example, when there is a D2D terminal, it can be used with offset_D2D (first offset) = 5 dB, and when there is no D2D terminal, offset_D2D (second offset) = 0 dB.

  In addition, the effect of offset_D2D can be obtained by making the setting of the variable existing in f (Rx_Power) different. The f (Rx_Power) formula of PUCCH can be set as follows.

  here

  Is a variable that is set for PUCCH performance in the upper layer, but one or a plurality of variables in this variable is divided into two sets and is used in a general subframe in which D2D is not set. A set and another set used in a subframe in which D2D is set are set. The terminal determines whether or not D2D is present in a subframe in which PUCCH is currently transmitted, and selects one of two variables or a set of variables and substitutes the selected variable into the above formula to use it for PUCCH power setting. be able to.

    The offset_D2D value may be set by the base station through signaling, or may be determined as an arbitrary value. Alternatively, a new DCI format can be defined by adding to a previously set DCI (Downlink Control Information) format, and the offset_D2D value can be notified to the terminal via the newly defined DCI format. For example, the offset_D2D value may be transmitted to the terminal through a physical downlink channel (Physical Downlink Control Channel). Alternatively, the information may be transmitted to the terminal using a field reserved in an arbitrary format among the previously defined DCI formats without defining a new DCI format, and any of the previously defined DCI formats may be transmitted. The offset_D2D value can be transmitted to the terminal by defining the field to have a different interpretation.

  Meanwhile, the function f (Rx_Power) in Equation (9) can be determined by the method described above.

  On the other hand, since it can be determined whether the cellular terminal transmits the D2D terminal at the same time, the base station may notify all terminals belonging to the base station of the subframe in which the D2D channel exists using the system information. it can. In addition, the base station can notify each terminal of the transmission time of the D2D terminal, and in this case, can notify the terminal via higher layer signaling or physical layer control information.

  Hereinafter, the operation procedure of the terminal and the base station according to the second embodiment of the present invention will be described. FIG. 7 is a flowchart illustrating an operation procedure of the terminal according to the second embodiment of the present invention.

  The cellular terminal starts operation in step 701, and acquires D2D transmission related information, for example, information about when and which subframe is used for D2D transmission, and offset_D2D information by D2D transmission in step 702.

  Information on the subframe in which the D2D transmission is performed can be used to determine which subframe is to use A and B, which are offset_D2D information received by the terminal.

  Also, regarding offset_D2D information by D2D transmission, if there is a D2D terminal, it is assumed that offset_D2D = A, and if there is no D2D terminal, if offset_D2D = B, the value for (A, B) is Can be set in

  The D2D transmission related information can be obtained from system information through a broadcast channel, and can be set and notified by a base station for each terminal.

In this case, higher layer signaling such as RRC can be used.

  The offset_D2D information is known through system information. Alternatively, the base station can notify the offset_D2D information for each terminal. In this case, higher layer signaling such as RRC can be used. Alternatively, the base station may define a new DCI format including the D2D transmission related information and the offset_D2D information, and the base station may transmit to the terminal via the PDCCH. Alternatively, the base station does not define a new DCI format and can transmit the information to the terminal using a field reserved in an arbitrary format among the previously defined DCI formats. Also, an offset_D2D value can be transmitted to the terminal by defining the interpretation of an arbitrary field of the DCI format defined in the past so that the interpretation is different.

  Next, the cellular terminal transmits cellular information to the base station in step 703.

  Information to be transmitted is prepared, and then in step 704, it is determined whether D2D transmission is performed at the time of transmitting cellular information using the D2D transmission related information acquired in step 702. For example, the terminal can determine whether a subframe in which cellular information is transmitted is a subframe in which D2D transmission is allowed.

  As a result of the determination, if the D2D transmission is combined, the terminal proceeds to step 705 and sets offset_D2D = A, that is, an offset value required when D2D transmission exists. On the other hand, if both D2D transmissions do not occur, the terminal proceeds to step 706 and sets offset_D2D = B, that is, an offset value required when there is no D2D transmission.

  Next, the terminal determines transmission power using the offset_D2D value set in step 707 and the following equation.

Tx_Power = min {Max_Tx_Power, f (Rx_Power) + offset_D2D} --- (10)

  In step 708, the terminal transmits cellular information using the transmission power, and then ends the transmission process in step 709.

  FIG. 8 is a flowchart illustrating an operation procedure of the base station according to the second embodiment of the present invention.

  In step 801, the base station starts operation, and in step 802 transmits information related to D2D transmission, that is, information about when and which subframe the D2D transmission consists. In step 803, the base station transmits cellular terminal power control information, that is, all information related to cellular terminal power control including offset_D2D information.

  The terminal can obtain the D2D transmission related information from the system information through a broadcast channel, and the base station can notify the information for each terminal. Similarly, the terminal can know the offset_D2D from the system information, or the base station can set and notify for each terminal. As another embodiment, a new DCI format including the D2D transmission related information and offset_D2D information may be defined, and the base station may transmit to the terminal via the PDCCH. Alternatively, the information may be transmitted to the terminal using a field reserved in an arbitrary format among the previously defined DCI formats without defining a new DCI format. The offset_D2D value can also be transmitted to the terminal by defining the field to be interpreted differently.

  In step 804, the operation is finished.

  FIG. 9 is a block diagram illustrating an internal structure of a terminal device for an embodiment according to the second embodiment of the present invention.

  Whether or not to perform D2D transmission is determined by the determinator 901 whether or not D2D transmission is present. The power control related setting value storage device 902 stores the power control related setting value received from the base station. When the determination information of the D2D transmission availability determination unit 901 and the information stored in the power control related setting value storage device 902 are input to the cellular transmission power controller 903, the transmission power for the cellular information transmitted by the terminal is determined.

  The offset_D2D value is stored in the power control related setting value storage device 902, and an accurate offset_D2D is determined by the cellular transmission power controller 903 according to the determination of the D2D transmission availability determination unit 901. A channel to be transmitted by the terminal is generated by the cellular channel generator 905 and amplified via the power amplifier 906. The value to be amplified is input to the power amplifier 906 by a value determined by the cellular transmission power controller 903. To be decided. The amplified cellular information is transmitted via the transmission unit 907.

  Each block shown in FIG. 9 does not necessarily have to be physically divided into hardware, and can be embodied as detailed functional blocks performed by the control unit.

  FIG. 10 is a block diagram showing an internal structure of a base station apparatus according to the second embodiment of the present invention.

  The D2D transmission related information generated by the D2D transmission time information generator 1001 and the cellular channel transmission power control related information generated by the cellular transmission related information generator 1002 are transmitted to the terminal via the transmission unit 1003.

  Hereinafter, a method for multiplexing D2D information and cellular information presented in still another embodiment of the present invention will be described.

  Problems in the situation where a cellular terminal transmits cellular information in the reverse direction to the base station, and a D2D terminal transmits to another D2D terminal using the same reverse frequency resource, and a solution through power control of the D2D terminal or the cellular terminal Described for.

  In the following, it is assumed that one terminal transmits D2D information or receives and transmits cellular information at the same time. The terminal can take a general cellular transmission that transmits reverse data information in the reverse direction (that is, at the base station) or transmits control information based on the forward data information in the reverse direction according to the scheduling of the base station. . However, there may occur a case where transmission or reception for D2D information for D2D is required simultaneously with the cellular transmission.

  The cellular transmission may include data transmission, and may include ACK / NACK transmission by forward data transmission, CQI transmission, and scheduling request information.

  In another embodiment of the present invention described below, an attempt is made to propose a solution for the case where the transmission of cellular information and the transmission / reception of D2D information occur simultaneously.

Embodiment 3: Simultaneous transmission of cellular channel and D2D channel In this embodiment, one terminal transmits reverse cellular information to the base station via the cellular channel and simultaneously transmits D2D information by other D2D terminals via the D2D channel. Assume the situation of transmission. The terminal uses a single carrier frequency division access (hereinafter referred to as SC-FDMA) transmission method.

  Therefore, it is assumed that the number of channels simultaneously transmitted by one terminal is limited to one. When the terminal has to transmit the cellular channel and the D2D channel at the same time, the following operation is possible. Preferably, any one of the operations described later can be selected and performed.

1. Only the D2D channel is transmitted.
2. Send only cellular channels.
3. Depending on the setting of the base station, one of the D2D channel and the cellular channel is selected and transmitted. (In this case, the base station gives priority to which channel when simultaneous transmission / reception of the D2D channel and the cellular channel occurs via system information, upper layer signaling such as RRC signaling, or physical layer control information) Such information can be transmitted to the terminal.)
4). Ignore the SC-FDMA system and transmit two channels simultaneously. At this time, the transmission power is first assigned to the cellular channel, and the remaining transmission power is assigned to the D2D channel.

Embodiment 4: Selective transmission of cellular channel and D2D channel by ACK / NACK In this embodiment, one terminal transmits reverse cellular information including ACK / NACK through the cellular channel at the base station, and simultaneously transmits the D2D channel. Assume a situation in which D2D information is transmitted by another D2D terminal through the D2D terminal.

  When the terminal transmits information on ACK / NACK at the base station, it means that the base station notifies whether the forward information received in advance is properly received via the ACK / NACK. Means that.

  If the information transmitted by the terminal to the base station is ACK / NACK, that is, if the reception of the forward information is accurate, if the ACK information is always transmitted to the base station, an additional retransmission is made. This can be prevented. On the other hand, if the information transmitted by the terminal at the base station is NACK in the ACK / NACK, the base station retransmits the forward information even if the NACK information is not transmitted to the base station. The need to send NACK information is less than the need to be sent.

  Therefore, in this embodiment, when one terminal transmits reverse cellular information including ACK / NACK at a base station via a cellular channel and simultaneously transmits D2D information at another D2D terminal via a D2D channel, Considering the importance of ACK and NACK, if the ACK / NACK information is ACK, the D2D channel is not transmitted and only the cellular channel is transmitted. If the ACK / NACK information is NACK, the cellular channel is not transmitted and only the D2D channel is transmitted. Suggest a way to send

  With respect to the above-described fourth embodiment of the present invention, the operation of the terminal will be described with reference to FIG.

  If operation of the terminal is started in step 1101 in FIG. 11, preparation for transmission of D2D information is performed in step 1102. In step 1103, if necessary, transmission for cellular information is prepared. In this case, information included in the PUCCH may be included in information for preparing transmission in step 1103.

  Next, in step 1104, the terminal determines whether uplink control information (PUCCH) needs to be transmitted. If PUCCH transmission is not necessary, the terminal transmits D2D information in step 1106. On the other hand, if it is determined in step 1104 that PUCCH transmission is necessary, it is further determined in step 1105 whether or not the ACK / NACK information included in the PUCCH is ACK or NACK.

  At this time, if the ACK / NACK information is ACK, the UE proceeds to step 1107 and transmits PUCCH. Meanwhile, if the ACK / NACK information is NACK, the UE proceeds to step 1106 and transmits D2D information.

  Step 1106 transmits D2D information but does not transmit PUCCH information. Step 1107 transmits PUCCH information but does not transmit D2D information.

  When the steps 1106 and 1107 are finished, the operation of the terminal is finished in step 1108.

  Embodiment 5: Cellular channel transmission and D2D channel reception selected simultaneously

  In the present embodiment, it is assumed that one terminal transmits reverse cellular information to a base station via a cellular channel and simultaneously receives D2D information from another D2D terminal via a D2D channel.

  A terminal cannot transmit and receive simultaneously via the same band. Accordingly, in the present invention, when the terminal has to perform the transmission of the cellular channel and the reception of the D2D channel at the same time, the following operation is possible. Preferably, any one of the operations described later can be selected and performed.

1. Only the D2D channel is received.
2. Send only cellular channels.
3. One of D2D channel reception and cellular channel transmission is selected according to the setting of the base station. (In this case, which operation the base station gives priority to between the transmission of the cellular channel and the reception of the D2D channel via system information, higher layer signaling such as RRC signaling, or control information of the physical layer) Can be transmitted to the terminal.)

  Embodiment 6: Selection for transmission of cellular control information and reception of D2D channel depending on the type of cellular control information

  In the present embodiment, it is assumed that one terminal transmits reverse cellular information including ACK / NACK at a base station via a cellular channel and simultaneously receives D2D information from another D2D terminal via a D2D channel.

  When the terminal transmits ACK / NACK information at the base station, the terminal notifies the base station of information regarding whether or not the forward information received from the base station is properly received via the ACK / NACK. It means that.

  If the information transmitted by the terminal at the base station is ACK / NACK, that is, if the reception of the forward information is accurate, if the ACK information is always transmitted to the base station, additional retransmission will occur. This can be prevented. On the other hand, if the information transmitted by the terminal at the base station is NACK in the ACK / NACK, the base station retransmits the forward information even if the NACK information is not transmitted to the base station. The need to send NACK information is reduced compared to the need to do so.

  Therefore, in the present embodiment, when one terminal transmits reverse cellular information including ACK / NACK at the base station via the cellular channel and simultaneously transmits D2D information at another D2D terminal via the D2D channel, Considering the importance of ACK and NACK, if the ACK / NACK information is ACK, the D2D channel is not received and the cellular channel is transmitted. If the ACK / NACK information is NACK, the cellular channel is not transmitted and the D2D channel is received. To do.

  An operation procedure of the terminal according to the present embodiment will be described with reference to FIG.

  If the operation of the terminal is started in step 1201 of FIG. 12, preparation for reception of D2D information is performed in step 1202, and transmission in cellular information is prepared in step 1203 if necessary. The cellular information in step 1203 may include information included in the PUCCH. In step 1204, the terminal determines whether PUCCH transmission is necessary. If it is determined that PUCCH transmission is not required, D2D information is received in step 1206.

  On the other hand, if it is determined in step 1204 that PUCCH transmission is necessary, it is determined in step 1205 whether the ACK / NACK information included in the PUCCH is ACK. At this time, if the ACK / NACK information is ACK, the UE proceeds to step 1207 and transmits PUCCH. Meanwhile, if the ACK / NACK information is NACK, the UE proceeds to step 1206 and receives D2D information.

  In step 1206, D2D information is received but PUCCH information is not transmitted. In step 1207, PUCCH information is transmitted but D2D information is not received. When step 1206 or step 1207 is completed, the operation of the terminal is ended in step 1208.

  According to the embodiment of the present invention described above, it is possible to prevent the situation in which the reception sensitivity lowering phenomenon occurs in the terminal that performs the existing cellular communication by controlling the transmission power of the terminal that performs the D2D communication. According to still another embodiment of the present invention, the operation of a terminal when one terminal performs cellular communication and D2D communication at the same time can be clearly defined.

  The embodiments of the present invention disclosed in this specification and the drawings are provided to illustrate the technical contents of the present invention and provide specific examples to help understand the present invention, and are intended to limit the scope of the present invention. It is not something to do. It is obvious to those skilled in the art to which the present invention pertains that other variations based on the technical idea of the present invention can be implemented in addition to the embodiments disclosed herein. is there.

401 transmission D2D terminal 402 reception D2D terminal 403 base station 501 storage unit 502 power control controller 503 control signal 504 channel generator 505 power amplifier 506 transmission unit 603 transmission unit 901 transmission availability determination unit 902 storage device 903 cellular transmission power controller 904 input 905 cellular Channel generator 906 Power amplifier 907 Transmitter 1001 Transmission time information generator 1002 Cellular transmission related information generator 1003 Transmitter

Claims (12)

In a power control method in a communication system,
A first terminal receiving power control related information from a base station;
When there is no uplink transmission from the first terminal , the first terminal transmits data to the second terminal based on transmission power, and
The method according to claim 1, wherein the transmission power is based on a first transmission power determined by the number of allocated resource blocks, a path loss, and the received power control related information.   The power control method according to claim 1, wherein the transmission power is further based on a second transmission power that is a maximum usable power for the data.   The power control method according to claim 2, wherein the transmission power is a value of a small transmission power among the first transmission power and the second transmission power.   The power control method of claim 1, wherein the data includes at least one of a discovery signal, control information, and data information.   The power control method according to claim 1, wherein the data is transmitted in a subframe set for the transmission of the data.   The method according to claim 1, wherein the path loss is calculated for a serving cell based on information provided by signaling of the base station. In the first terminal in the communication system,
A transmission / reception unit for transmitting / receiving signals to / from a terminal or a base station;
A control unit that receives power control related information from the base station and controls to transmit data to the second terminal based on transmission power when there is no uplink transmission from the first terminal , and
The terminal is characterized in that the transmission power is based on a first transmission power determined by the number of allocated resource blocks, a path loss, and the received power control related information.   The terminal according to claim 7, wherein the transmission power is further based on a second transmission power which is a maximum usable power for the data.   The terminal according to claim 8, wherein the transmission power is a value of a small transmission power among the first transmission power and the second transmission power.   The terminal of claim 7, wherein the data includes at least one of a discovery signal, control information, and data information.   The terminal according to claim 7, wherein the data is transmitted in a subframe set for transmission of the data.   The terminal according to claim 7, wherein the path loss is calculated for a serving cell based on information provided by signaling of the base station.

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