JP2020072319A - Wireless communication device and wireless communication system - Google Patents

Abstract

To improve transmission reliability of low-delay transmission data and reduce a delay in transmission of low-delay transmission data while maintaining average transmission power of the entire system band at a predetermined power.SOLUTION: Low-delay transmission data that requires low-delay communication is transmitted in a resource allocation area allocated to a part of a system band in a frequency direction of a data channel area of a subframe forming a wireless frame. Transmission power is controlled to increase the transmission power of the resource allocation area for the low-delay transmission data to be higher than that for resources other than the resource allocation area for the low-delay transmission data in a frequency direction of the data channel area under a condition that average transmission power of the entire system band is maintained at a predetermined power.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a mobile communication wireless communication device and a wireless communication system.

  Conventionally, a mobile communication system using adaptive modulation and coding control (AMC) based on response (ACK / NACK) feedback regarding data transmission success or failure and hybrid ARQ (HARQ) retransmission in the mobile communication system is known (for example, Non-Patent Document 1). reference). In this technology, a certain initial transmission block error is allowed in order to improve frequency utilization efficiency by transmitting data with a modulation level as high as possible and a coding rate as high as possible, and the initial transmission block error is based on ACK / NACK feedback. A combination of a data modulation method and an error correction coding rate (MCS) is controlled so that the rate becomes a target value, and ACK is transmitted for a data block in which a transmission error is detected (that is, NACK is fed back). By performing feedback or HARQ retransmission until the maximum number of retransmissions that is defined in advance is reached, transmission errors are reduced and transmission reliability in the wireless section is improved. According to this technique, it is possible to improve both frequency utilization efficiency and high reliability of wireless transmission. AMC based on ACK / NACK feedback is sometimes called Outer-Loop Link Adaptation (OLLA).

F. Blanquez-Casado et al, "eOLLA: an enhanced outer loop link adaptation for cellular networks," EURASIP Journal on Wiring 16th and 20th Anniversary. 2016. DOI: 10.1186 / s13638-016-0518-3.

  However, in the above-mentioned conventional technique, since the transmission delay dispersion in the wireless section increases due to the increase in the transmission delay due to the retransmission for improving the data transmission reliability, end-to-end low-delay and high-reliability wireless transmission. There is a problem that it becomes difficult to realize simultaneously.

  In addition, URLLC (Ultra Reliable & Low Latency Communication) is being considered as one of the use cases of the 5th generation (5G) mobile communication system of the 3GPP (3rd Generation Partnership Project). Has been done. In particular, in this URLLC communication, a wireless transmission technology that achieves both low delay and high reliability is required.

A radio communication device according to one aspect of the present invention is a radio communication device of a mobile communication system, in a resource allocation region allocated to a part of a system band in a frequency direction of a data channel region of a subframe forming a radio frame. A transmitter for transmitting low-delay transmission data requiring low-delay communication, and the low-frequency transmission data in the frequency direction of the data channel region under the condition of maintaining an average transmission power of the entire system band at a predetermined power. A transmission power control unit that controls the transmission power so that the transmission power of the resource allocation area of the delayed transmission data is higher than the resource areas other than the resource allocation area of the low delay transmission data.
In the wireless communication device, the transmitting unit may transmit control information including information defining a resource allocation area of the low delay transmission data in a control channel area of the subframe.
In the wireless communication device, when TDD (Time Division Duplex) is used as a duplex system, the data channel region is a resource region for receiving a retransmission control response for the low delay transmission data from a destination of the low delay transmission data. May be assigned. Here, in the frequency direction of the data channel region, the transmission power of the resource allocation region of the retransmission control response is equal to the retransmission control response under the condition that the average transmission power of the entire system band is maintained at a predetermined power. The resource allocation area may be higher than the other resource areas.
In the wireless communication device, the resource allocation area of the low-delay transmission data may be located at a leading portion in the time direction of the data channel area.
In the wireless communication device, the resource allocation area of the low delay transmission data may be located at a plurality of locations in the frequency direction in the data channel area.
In the wireless communication device, resource allocation regions of the low delay transmission data may be dispersedly located at both ends in the frequency direction of the data channel region.
In the wireless communication device, the transmission unit may transmit a reference signal for demodulating the low-delay transmission data together with the low-delay transmission data in a resource allocation area of the low-delay transmission data.
In the wireless communication device, the low delay transmission data may be URLLC (Ultra-Reliable and Low Latency Communications) data.

A wireless communication system according to still another aspect of the present invention is a wireless communication device on the transmission side that transmits the low-delay transmission data, and a reception device that receives the low-delay transmission data transmitted from the wireless communication device on the transmission side. Side wireless communication device.
In the wireless communication system, the wireless communication device on the receiving side may receive wireless signals of the low-delay transmission data at different positions or receive wireless signals of different polarizations of the low-delay transmission data. It is also possible to have a plurality of antennas provided in the antenna and execute reception antenna diversity for selecting or combining reception signals received by the respective antennas.
In the wireless communication system, the wireless communication device on the transmitting side transmits the wireless signals of the low-delay transmission data at different positions or the wireless signals of the low-delay transmission data of different polarizations. It is also possible to have a plurality of antennas provided in, and to perform transmission antenna diversity for selecting or combining transmission signals to be transmitted by each antenna.
In the wireless communication system, the wireless communication device on the transmission side may perform the transmit antenna diversity by performing space-time coding or space-frequency coding on the low-delay transmission data.
In the wireless communication system, the transmitting antenna diversity may be a cyclic delay fiber type.

A wireless communication method according to still another aspect of the present invention requires low-delay communication in a resource allocation area allocated to a part of a system band in a frequency direction of a data channel area of a subframe forming a wireless frame. Transmitting low-delay transmission data, and transmitting power of the low-delay transmission data resource allocation region under the condition of maintaining an average transmission power of the entire system band at a predetermined power in the frequency direction of the data channel region. And controlling the transmission power so as to be higher than resource areas other than the resource allocation area of the low delay transmission data.
A program according to still another aspect of the present invention is a program executed in a computer or a processor included in a mobile communication wireless communication device, and is a program of a system band in a frequency direction of a data channel region of a subframe forming a wireless frame. In the resource allocation area allocated to a part, a program code for transmitting low-delay transmission data that requires low-delay communication,
In the frequency direction of the data channel region, the wireless communication device sets the transmission power of the resource allocation region of the low-delay transmission data to the low transmission power under the condition that the average transmission power of the entire system band is maintained at a predetermined power. And a program code for controlling transmission power so as to be higher than resource areas other than the resource allocation area of the delayed transmission data.

  According to the present invention, it is possible to improve the transmission reliability of low-delay transmission data and reduce the delay in the transmission of low-delay transmission data while maintaining the average transmission power of the entire system band at a predetermined power.

Explanatory drawing which shows an example of a schematic structure of the radio | wireless communications system which concerns on this embodiment. (A) And (b) is explanatory drawing which shows the resource allocation of the sub-frame which concerns on a reference example. FIG. 6A is an explanatory diagram showing an example of resource allocation of subframes in the wireless communication system according to the present embodiment. FIG. 6B is a graph showing an example of transmission power distribution in the frequency axis direction when URLLC data is transmitted in the same subframe. FIG. 6A is an explanatory diagram showing another example of resource allocation of subframes in the wireless communication system according to the present embodiment. FIG. 6B is a graph showing an example of transmission power distribution in the frequency axis direction when URLLC data is transmitted in the same subframe. Explanatory drawing which shows the further another example of the resource allocation of the sub-frame in the radio | wireless communications system which concerns on this embodiment. Explanatory drawing which shows the further another example of the resource allocation of the sub-frame in the radio | wireless communications system which concerns on this embodiment. FIG. 6A is an explanatory diagram showing still another example of resource allocation of subframes in the wireless communication system according to the present embodiment. FIG. 6B is a graph showing an example of transmission power distribution in the frequency axis direction when URLLC data is transmitted in the same subframe. Explanatory drawing which shows the further another example of the resource allocation of the sub-frame in the radio | wireless communications system which concerns on this embodiment. The functional block diagram which shows an example of the base station by the side of the transmission in the radio | wireless communications system which concerns on this embodiment. The sequence diagram which shows an example of transmission / reception of the transmission data containing the URLLC data of the downlink which concerns on this embodiment. The sequence diagram which shows the other example of transmission / reception of the transmission data containing the URLLC data of the downlink which concerns on this embodiment. The sequence diagram which shows another example of transmission / reception of the transmission data containing the URLLC data of the downlink which concerns on this embodiment. (A), (b) and (c) are explanatory views showing an example of antenna diversity applicable to the wireless communication system according to the present embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a wireless communication system according to the present embodiment.
1, a wireless communication system 10 includes a base station 20 as a wireless communication device that functions as a transmitter and a receiver for wireless communication, and a mobile station as a wireless communication device that functions as a transmitter and a receiver for wireless communication. And 30. There may be a plurality of base stations 20 and mobile stations 30, respectively.

  The base station 20 is connected to a mobile communication core network 80. For example, when the base station 20 functions as a transmitter and the mobile station 30 functions as a receiver, data from the core network 80 or another mobile station or data generated by the base station 20 is moved from the base station 20. It is possible to perform downlink (DL) wireless communication for transmission to the station 30. Further, the base station 20 functions as a receiver and the mobile station 30 functions as a transmitter, so that uplink (UL) wireless communication for transmitting the data generated by the mobile station 30 to the base station 20 can be performed. it can. The data received at the base station 20 is transmitted to the core network 80 or another mobile station, or processed within the base station 20.

  In DL data transmission, ACK / NACK feedback for HARQ retransmission is performed through UL. On the other hand, in UL data transmission, ACK / NACK feedback for HARQ retransmission is performed through DL.

  The wireless communication system 10 of the present embodiment may use a communication method based on a communication standard of 3GPP fourth generation (4G), LTE (Long Term Evolution), LTE-Advanced, or LTE-Advanced Pro, or the fifth. You may use the communication system based on the communication standard of the next generation (5G) or the next generation.

  The wireless communication system 10 according to the present embodiment is a high-speed and large-capacity eMBB (enhanced Mobile Broadband), an ultra-reliable and low-latency URLLC (Ultra-Reliable and Low Latency Communications), which has been studied as a 5G use case, and multiple terminals It can be applied to data communication such as mMTC (massive Machine Type Communications) which is a simultaneous connection. In particular, the wireless communication system 10 of the present embodiment has low data such as eMBB data (hereinafter referred to as “eMBB data”) and URLLC data (hereinafter referred to as “URLLC data”) assuming automatic driving, telemedicine, and the like. It is suitable for wireless communication that transmits and receives delayed transmission data. Here, low-delay transmission data such as URLLC data is required to have a one-way delay time of several ms or less (for example, 1 ms or less) in a wireless section of a mobile communication network, and end-to-end communication via the mobile communication network is required. The data is required to have an end delay time of 10 ms or less.

  The base station 20 forms one or a plurality of cells (also referred to as sectors or sector cells). The cells may be formed two-dimensionally on the ground or the sea, or may be formed three-dimensionally from the sky to the ground or the sea. The cell may be a macro cell, a small cell, a femto cell, a pico cell, a large cell, or the like. The plurality of cells may form a cellular structure in which they are distributed so as to be adjacent to each other in a two-dimensional or three-dimensional manner, or may form a hierarchical cell structure in which some or all of them are hierarchically overlapped. .. The base station 20 is a macro cell base station, a small cell base station, a femto cell base station, a pico cell base station, a large cell base station, a fixed base station fixedly installed on the ground, etc. Type base station or the like. The base station 20 may be a wireless communication device called an eNodeB (evolved Node B: eNB), a gNodeB (gNB), an en-NodeB (en-gNB), an access point, or the like.

  The mobile station 30 may be a wireless communication device called a user equipment (UE), a user terminal, a terminal, a terminal device, a mobile device, or the like. The mobile station 30 can be installed by being installed in a device that can be used while being carried by a user, a device that can be used in a moving body (for example, a car, a train, a flying body, or a ship), or a moving body or another device. It may be a device or the like. The mobile station 30 may perform communication while moving, or may perform communication while being fixedly arranged.

  In the wireless communication system of this embodiment, various multiple access technologies can be used. The multiple access technology is a frequency division multiple access (FDMA), a time division multiple access (TDMA), or a frequency division multiple access (TDMA) that allocates different frequencies or times or spreading codes to a plurality of mobile stations. , A code division multiple access (CDMA) system may be used. The multiple access technology may be a space division multiple access scheme (SDMA) that assigns different base station antenna directivities to each of a plurality of mobile stations.

  The multiple access technology is a multiple access technology based on Orthogonal Frequency Division Multiplexing (OFDM), which is classified as one of the FDMA technologies, that is, an Orthogonal Frequency Division Multiple Access (OFDMA) method. It may be a method called.

  The FDMA, TDMA, CDMA, and SDMA multiple access schemes allocate mutually orthogonal or quasi-orthogonal radio resources of different frequencies, times, spreading codes, and base station antenna directivities to mobile stations. Multiple access schemes are broadly classified as orthogonal multiple access (OMA) technologies.

  In the wireless system of the present embodiment, a single orthogonal multiple access (OMA) technique may be used, or a hybrid type in which two or three of the OMA techniques such as FDMA, TDMA, CDMA, and SDMA are used together. Method, such as a combination of FDMA and TDMA, a combination of FDMA, TDMA and SDMA, may be used together.

  The radio system according to the present embodiment uses a MU-MIMO transmission system that multiplexes communication of a plurality of mobile stations at the same frequency and at the same timing based on the SDMA principle classified as orthogonal multiple access (OMA technology). It may be a density multiple access type wireless communication system. A non-orthogonal multiple access (NoMA) technique that allows mutual interference in part or all of the radio resources assigned to each mobile station may be applied to the ultra-high-density multiple-access wireless communication system.

  In the wireless system of this embodiment, different multiple access schemes may be used for downlink communication and uplink communication. For example, OFDMA may be used for downlink communication and FDMA (Single Carrier-FDMA) may be used for uplink communication.

  In the wireless section between the base station 20 and the mobile station 30, wireless communication is performed using one or a plurality of wireless frames. The wireless frame has, for example, a system band having a predetermined frequency width (for example, 20 MHz) set in a predetermined frequency band in the frequency axis direction (for example, several hundred MHz, several GHz, several tens GHz, etc.) A predetermined time interval (for example, 10 ms) is set in the axial direction. The system band is set according to the frequency band used and the like, and may be 40 MHz, 80 MHz, 160 MHz or 400 MHz in addition to 20 MHz.

  The radio frame is composed of one or a plurality of subframes having a predetermined transmission time interval (TTI) which is the minimum unit of scheduling in the time axis direction. For example, when the TTI is 1 ms, the radio frame is composed of 10 subframes. The TTI may be 0.5 ms, 0.25 ms or 0.125 ms in addition to 1 ms. By shortening the TTI to shorten the wireless frame length, it is possible to reduce the transmission delay in the wireless section.

  The radio frame is composed of one or a plurality of subcarriers having a predetermined subcarrier interval (for example, 15 kHz) in the frequency axis direction. The subcarrier interval is set according to the frequency band, system band, etc., and may be 30 kHz, 60 kHz, or 120 kHz in addition to 15 kHz. The subframe may be composed of, for example, one or a plurality of slots in the time axis direction, and one slot may be composed of one or a plurality of (for example, 6 or 7) symbols.

  In the wireless communication system of this embodiment, scheduling is performed to allocate the above-described TTI, system band, transmission power, and other wireless resources that can be used for wireless communication of various data and signals between the base station 20 and the mobile station 30. The scheduling is performed by the base station 20, for example. The allocation of each direction of the frequency axis and the time axis of the radio resource is performed with one or a plurality of resource elements (RE) as the minimum unit. The resource element (RE) is composed of, for example, one subcarrier and one symbol. When the minimum unit of resource allocation is composed of a plurality of resource elements (RE), a block in which the minimum unit of resource allocation is composed of a plurality of resource elements may be called a resource block (RB). A symbol is one unit of modulation in the time axis direction in the above various communication systems. For example, the symbols in OFDM are called OFDM symbols.

  Note that the configuration of the radio frame in the present embodiment is an example, and the number of subframes included in the radio frame, the number of slots included in the subframe, the number of subcarriers and symbols, and the resource element (subelement included in the resource block The number of carriers, symbols) can be changed variously.

  The wireless communication system of the present embodiment performs downlink (DL) wireless communication from the base station 20 to the mobile station 30 as follows. For example, the downlink control information (DCI) is transmitted from the base station 20 to the mobile station 30 using the downlink control channel area arranged in a predetermined area of the subframe. The downlink control channel is also referred to as PDCCH (Physical Downlink Control Channel) or ePDCCH (enhanced Physical Downlink Control Channel) in LTE, LTE-Advanced, and 5G, for example, and uplink and downlink radio resource allocation information for each mobile station, MCS of data signal. , ACK / NACK feedback related to uplink HARQ retransmission control, transmission power control to each mobile station, etc. The downlink data is transmitted from the base station 20 to the mobile station 30 using the downlink data channel area arranged in a predetermined area of the subframe. The downlink data channel is also called, for example, PDSCH (Physical Downlink Shared Channel). The downlink signal includes a reference signal (RS) for channel estimation for demodulating data from the received signal, symbol timing synchronization, reception quality measurement, and the like. The data demodulation reference signal includes DMRS (Demodulation Reference Signal) and CRS (Cell-specific Reference Signal), and the quality measurement reference signal includes CSI-RS (Channel State Information Reference Signal).

  The wireless communication system of the present embodiment performs, for example, uplink (UL) wireless communication from the mobile station 30 to the base station 20 as follows. For example, the uplink data is transmitted from the mobile station 30 to the base station 20 using the uplink data channel area arranged in a predetermined area of the subframe. The uplink data channel is also called a PUSCH (Physical Uplink Shared Channel) in LTE, LTE-Advanced, and 5G, for example. The uplink signal includes a reference signal (RS) for propagation channel estimation for demodulating data from the received signal, symbol timing synchronization, reception quality measurement, and the like. The data demodulation reference signal includes a DMRS (Demodulation Reference Signal), and the quality measurement reference signal includes an SRS (Sounding Reference Signal). The PUCCH (Physical Uplink Control Channel) corresponding to the uplink control channel is used for feedback such as quality measurement results using CRS and CSI-RS in the downlink, and ACK / NACK feedback related to downlink HARQ retransmission control. Used.

  In the case of LTE or LTE-Advanced, for example, the control channel region is set to the head region (for example, one symbol or two symbols) in the time axis direction of the subframe, and the data channel region follows the control channel region. It is set in the remaining area.

  Also, in the wireless communication system of the present embodiment, hybrid ARQ (HARQ) retransmission control and adaptive modulation and coding (AMC) that selects a modulation and coding scheme based on the response (ACK / NACK) of the HARQ. ) You are in control. In the HARQ control and the AMC control, a certain transmission error and a plurality of retransmissions are allowed, and the modulation level and the coding rate in the wireless transmission are controlled based on the ACK / NACK feedback result from the receiving side, thereby performing the wireless transmission. We are aiming for higher reliability.

  Next, allocation of radio resources used for radio communication of low-delay transmission data in the radio communication system of this embodiment will be described. In the present embodiment, a case where the URLLC data that is low delay transmission data and the eMBB data that is another data (hereinafter referred to as “eMBB data”) in one subframe are DL-communicated from the base station 20 to the mobile station 30. To illustrate.

  FIGS. 2A and 2B are explanatory diagrams showing resource allocation of the subframe 400 according to the reference example. 2A shows resource allocation when there is no URLLC traffic, and FIG. 2B shows resource allocation when there is URLLC traffic. The first area in the time axis direction of the subframe 400 is a control channel area 410 to which DL control information can be assigned, and the remaining area after that is a data channel area to which transmission data (URLLC data, eMBB data) can be assigned. It is 420.

  When there is no URLLC traffic shown in FIG. 2A, the resources of the eMBB data are allocated to the entire data channel area 420 of the subframe 400 to ensure high-speed and large-capacity data from the base station 20 to the mobile station 30. I am ready to send.

  When there is traffic of the URLLC of the user # 1 shown in FIG. 2B, the URLLC of the user # 1 is minimized so that the resource allocation bandwidth is minimized for some subcarriers of the data channel area 420 of the subframe 400. A data resource (hereinafter, also referred to as “URLLC resource”) 422 is preferentially allocated in the time axis direction, and a user # 2 eMBB data resource (hereinafter, “eMBB resource”) is allocated to the remaining part of the data channel region 420. 421) is assigned.

  In the present reference example, the URLLC resource 422 is allocated in a narrow band frequency range, and it is difficult to obtain the frequency diversity effect during wireless transmission of URLLC data. Therefore, not only the reliability of wireless transmission of URLLC data is lowered, but also retransmission is likely to occur, so that transmission delay dispersion due to retransmission increases and low-delay wireless transmission is difficult.

  Therefore, in the present embodiment, when there is URLLC traffic, resource allocation of URLLC data is minimized so that resource allocation bandwidth in the subframe 400 is not minimized but allocation in the time axis direction is minimized according to size. It is carried out.

  In the following embodiments, the first data (normally delayed transmission data) is the eMBB data among the plurality of types of transmission data transmitted from the base station 20 in the data channel area of the subframe, and is more than the first data. The case where the second data (low-delay transmission data) that requires low-delay wireless transmission is URLLC data will be described, but it may be a combination of other data. Further, in the present embodiment, downlink radio transmission from the base station 20 to the mobile station 30 will be described, but resource allocation of subframes, transmission power control, and the like in the present embodiment are performed from the mobile station 30 to the base station 20. Similarly, it can be applied to the wireless transmission of the uplink.

(Example 1)
FIG. 3A is an explanatory diagram showing an example of resource allocation of the subframe 400 in the wireless communication system according to the present embodiment, and FIG. 3B is a frequency axis direction during URLLC data transmission in the subframe 400. 5 is a graph showing an example of the transmission power distribution of

  As shown in FIG. 3A, in the data channel area 420 of the subframe 400, according to the size of the URLLC data under the condition that the resource allocation amount of the URLLC data in the time direction is minimized in the unit of resource element. The URLLC resource 422 is assigned to a part or the whole of the system band in the frequency direction. In this embodiment, the allocation of the resource 422 for URLLC is the resource allocation in the frequency direction priority. Therefore, as compared with the case of preferential allocation in the time axis direction (symbol direction), the URLLC data can be transmitted in a shorter time, and the wideband wireless transmission is performed, so that the frequency diversity effect is easily obtained. Therefore, the transmission reliability of the URLLC data is improved, and the probability of retransmission of the URLLC data can be reduced, so that the wireless transmission of the URLLC data can be delayed.

  As shown in FIG. 3B, in this example, the transmission power P422 in the transmission band of the URLLC resource 422 in the frequency axis direction and the other eMBB resources 421 at the timing of transmitting the URLLC data. The transmission power P421 in the transmission band is the same as each other.

  Further, in the example of FIG. 3A, the DL control information transmitted to the mobile station 30 prior to the URLLC data includes the resource allocation information in the subframe 400. For example, the information defining the resource allocation area of the URLLC data (hereinafter also referred to as “URLLC resource allocation information”) is information defining the frequency range in the frequency axis direction to which the URLLC resource 422 is allocated (for example, subcarrier (Identification information) and information defining a time range (for example, a symbol range) in the time axis direction. Upon receiving the control information, the mobile station 30 receives, demodulates and decodes the URLLC data transmitted in the same subframe 400 based on the URLLC resource allocation information included in the control information of the head part of the subframe 400. be able to.

  Moreover, as shown in FIG. 3A, since the URLLC resources 422 are continuously allocated in the frequency axis direction, the information amount of the URLLC resource allocation information included in the control information can be reduced.

  Further, in FIGS. 3A and 3B, the URLLC data of the subframe 400 includes a DMRS used for estimating a propagation path for demodulating the URLLC data from the received signal.

(Example 2)
FIG. 4A is an explanatory diagram showing another example of resource allocation of the subframe 400 in the wireless communication system according to the present embodiment, and FIG. 4B is a frequency when URLLC data is transmitted in the subframe 400. It is a graph which shows an example of transmission power distribution of the direction of an axis. In addition, in FIGS. 4A and 4B, the description of the portions common to the above-described FIGS. 3A and 3B will be omitted.

  In the example of FIGS. 4A and 4B, the transmission power P422 in the URLLC resource 422 is set under the condition that the average transmission power of the entire system band is maintained at a predetermined power at the transmission timing of the URLLC data. , The transmission power is controlled so as to be higher than the resource area other than the URLLC resource 422 (eMBB resource 421 ′ in this example). By thus concentrating the transmission power in the URLLC resource 422, the reception quality of the URLLC data (URLLC packet) can be further improved, so that the retransmission occurrence rate of the URLLC data can be further reduced. Therefore, it is possible to further reduce the delay of the transmission of the URLLC data.

  Note that the transmission power assigned to the eMBB resource 421 'may be 0. In this case, it is equivalent to not allocating the eMBB resource at the transmission timing of the URLLC data.

(Example 3)
FIG. 5 is an explanatory diagram showing still another example of resource allocation of the subframe 400 in the wireless communication system according to the present embodiment. Note that, in FIG. 5, the description of the portions common to the above-described FIGS. 3A and 4A is omitted.

  In the example of FIG. 5, the URLLC resource 422 is allocated to the head portion in the time direction (the portion adjacent to the control channel area 410) in the data channel area of the subframe 400. In this example, by transmitting the URLLC data in the head part of the data channel area 420 of the subframe 400, the response (ACK / NACK) to the URLLC data is received in the same subframe 400, and the HARQ based on the response is received. It is possible to retransmit the data by using, and the HARQ RTT (Round-Trip Time) can be reduced as much as possible.

(Example 4)
FIG. 6 is an explanatory diagram showing still another example of resource allocation of the subframe 400 in the wireless communication system according to the present embodiment. This example is an example of using TDD (Time Division Duplex) as the duplex system. It should be noted that in FIG. 5, description of portions common to those in FIGS. 3 (a), 4 (a), and 5 is omitted.

  In the example of FIG. 6, the URLLC resource 422 is assigned to the time direction head portion (the portion adjacent to the control channel area 410) in the data channel area 420 of the subframe 400, and a technique called “Self-Contained TDD subframe” is used. It is applied to the data channel region 420. In this example, the response (ACK / NACK) to the URLLC data DL-transmitted in the head part of the data channel area 420 is moved by the HARQ-ACK / NACK resource 423 assigned to the subsequent area in the same data channel area 420. It is received from station 30. Based on the response (ACK / NACK) fed back from the mobile station 30 within the data channel region 420 of the same subframe 400, HARQ retransmission control can be promptly performed. For example, it is possible to promptly determine the completion of the transmission of the URLLC data based on ACK, or promptly retransmit the URLLC data based on NACK. Therefore, it is possible to further reduce the delay in wireless transmission of URLLC data.

  The HARQ-ACK / NACK resource 423 in FIG. 6 may retransmit the URLLC data based on the HARQ response (NACK).

  FIG. 7A is an explanatory diagram showing still another example of resource allocation of the subframe 400 in the wireless communication system according to the present embodiment, and FIG. 7B is when URLLC data is transmitted in the subframe 400. It is a graph which shows an example of transmission power distribution of a frequency axis direction. Note that, in FIGS. 7A and 7B, description of portions common to those in FIGS. 3 to 6 will be omitted.

(Example 5)
In the example of FIGS. 7A and 7B, under the condition that the average transmission power of the entire system band is maintained at a predetermined power at the transmission timing of the response (ACK / NACK) to the URLLC data in the mobile station 30. Then, the transmission power is controlled so that the transmission power in the HARQ-ACK / NACK resource 423 is higher than that in the UL resource 424 other than the HARQ-ACK / NACK resource. In this way, by concentrating the transmission power in the HARQ-ACK / NACK resource 423 in the mobile station 30, the response (ACK / NACK) to the URLLC data can be more reliably fed back to the base station 20. It is possible to reduce the delay of data transmission. For example, it is possible to suppress HARQ-ACK reception errors and reduce the transmission delay time.

  When the HARQ-ACK / NACK resource 423 in FIG. 6 retransmits the URLLC data based on the HARQ response (NACK) in the examples of FIGS. 7A and 7B, the transmission at the retransmission timing is performed. The transmission power may be controlled so that the power is higher than that of other eMBB resources. The transmission power value assigned to the HARQ-ACK / NACK resource 423 is determined and controlled so that the data transmission side (the base station 20 in DL, the mobile station 30 in UL) has a target value based on the required reception quality on the data reception side. It may be determined by closed-loop transmission power control that indicates (controls) the transmission power, or the target value based on the required reception quality based on the reception power measurement result of the reference signal (reference signal) from the data transmission side by the data reception side. It may be determined by a case (open loop transmission power control) in which control and determination are voluntarily performed so that

  Further, when the reception quality of the HARQ-NACK signal is poor and the HARQ-NACK signal cannot be received at the data transmission side at a predetermined timing, it is generally considered that the data transmission side receives the HARQ-NACK. Be done. Therefore, only when transmitting the HARQ-ACK for the URLLC data, a process of increasing the resource for other eMBB is applied, and when transmitting the HARQ-NACK, the transmission power is minimized to reduce the power consumption of the mobile station. In order to save the power, it is not necessary to perform the process of increasing the transmission power assigned to the HARQ-ACK / NACK resource 423 for the URLLC data over the eMBB resource.

(Example 6)
FIG. 8 is an explanatory diagram showing still another example of resource allocation of subframes in the wireless communication system according to the present embodiment. In FIG. 8, description of portions common to those in FIGS. 3 to 7 will be omitted.
In the example of FIG. 8, the entire URLLC data cannot be transmitted in one unit (one symbol time) of resource elements included in the subframe 400 formed of a plurality of symbols. Therefore, by allocating the URLLC resource 422 to all of the first symbol and a part of the second symbol of the head portion in the time axis direction of the data channel area of the subframe 400, the URLLC resource allocation information included in the control information The amount of information is reduced, and URLLC data can be reliably transmitted within one subframe 400.

  When it is necessary to increase the transmission power density allocated to the URLLC data resource, such as when the mobile station 30 is far from the base station 20 and the propagation loss is large, the transmission power allocation to the eMBB resource 421 ′ is set to 0 or the URLLC is set. The number of resource blocks (bandwidth) allocated to the data resource may be reduced to further increase the resource allocation amount in the time axis direction.

  In the examples of FIGS. 3 to 8 described above, the URLLC resource 422 and the HARQ-ACK / NACK resource 423 are continuously allocated in the frequency axis direction of the subframe 400, but a frequency having a high propagation path gain in the wireless section is used. May be preferentially assigned. For example, bitmap-type allocation may be performed such that at least one of the URLLC resource 422 and the HARQ-ACK / NACK resource 423 is dispersed in a plurality of locations in the frequency axis direction and is discontinuously allocated. Further, in order to obtain frequency diversity in the open loop, band edge distributed allocation may be performed by distributing the system band at both ends in the frequency direction.

  FIG. 9 is a functional block diagram showing an example of the transmission-side base station 20 in the wireless communication system according to this embodiment. The same configuration can be applied when the mobile station 30 serves as the transmitting side.

  In FIG. 9, the base station 20 includes a URLLC data resource allocation unit 210, a transmission unit 220, and an information storage unit 230.

  When the URLLC data is included in the transmission target, the resource allocation unit 210 minimizes the resource allocation amount in the time direction of the URLLC data in the data channel area of the subframe forming the radio frame in resource element units. Then, the resource of the URLLC data (resource for URLLC) is allocated to a part or the whole of the system band in the frequency direction according to the size of the URLLC data. The resource allocation unit 210 may allocate resources for HARQ-ACK / NACK together with resources for URLLC in the same subframe 400. The transmission unit 220 transmits the URLL data in the URLLC resource in the subframe 400 allocated by the resource allocation unit 210.

  The resource allocation unit 210 includes, for example, a data size calculation unit 211, a resource determination unit 212, and an information storage unit 213.

  The data size calculation unit 211 calculates the size of the URLLC data included in the transmission target transmitted in the subframe 400.

  The resource determination unit 212 minimizes the resource allocation amount in the time direction of the URLLC data in the data channel area 420 of the subframe 400 based on the size of the URLLC data calculated by the data size calculation unit 211 in resource element units. Under such a condition, the URLLC resource is determined so that the URLLC resource is allocated to a part or the whole of the system band in the frequency direction according to the size of the URLLC data. Moreover, when allocating the resource for URLLC and the resource for HARQ-ACK / NACK in the same sub-frame 400, the resource determination part 212 also determines about the resource for HARQ-ACK / NACK. The resource determination unit 212 passes the resource allocation information for the determined URLLC resource or both the URLLC resource and the HARQ-ACK / NACK resource to the transmission unit 220.

  The transmission unit 220 includes a transmission data acquisition unit 221, a transmission signal generation unit 222, and a wireless communication unit 223.

  The transmission data acquisition unit 221 acquires URLLC data addressed to the mobile station 30 from the core network 80 of the mobile communication network, for example. The transmission data acquisition unit 221 may acquire URLLC data from another mobile station, or may acquire it from an information processing device such as a computer device such as MEC (Mobile Edge Computing) provided in the base station 20. .. When the wireless communication device on the transmission side is the mobile station 30, the transmission data acquisition unit 221 may acquire data generated based on the outputs of various sensors and measuring devices provided in the mobile station 30.

  The transmission signal generation unit 222 includes transmission target transmission data including eMBB data and URLLC data received from the transmission data acquisition unit 221, resource allocation information received from the resource allocation unit 210, and transmission parameters read from the information storage unit 230. Based on various information such as, the control information and the transmission data transmitted in the subframe 400 are subjected to processing such as encoding and modulation to generate a transmission signal. For example, in the control channel area 410 of the subframe 400, the resource allocation information for the URLLC resource or both the URLLC resource and the HARQ-ACK / NACK resource is arranged, and the URLLC resource of the data channel area 420 of the subframe 400 is set. The transmission signal is generated so that the URLLC data is arranged and the eMBB data is arranged in a portion other than the URLLC resource of the data channel area 420.

  The wireless communication unit 223 performs predetermined frequency conversion and power amplification on the transmission signal generated by the transmission signal generation unit 222, and transmits it as a wireless signal from the antenna 21. The wireless communication unit 223 may perform control for concentrating power resources on the URLLC resources described above.

  The information storage unit 230 stores various information such as transmission parameters used for allocation of URLLC resources and HARQ-ACK / NACK resources.

  FIG. 10 is a sequence diagram showing an example of transmission / reception of transmission data including downlink URLLC data according to the present embodiment. FIG. 10 shows an example of transmitting URLLC data in the subframes of FIGS. 3 and 4 described above.

  In FIG. 10, the base station 20 acquires transmission data to be transmitted including eMBB data and URLLC data to be transmitted in the target subframe (S101), calculates the size of the URLLC data (S102), and calculates the URLLC data The URLLC resource in the data channel area of the subframe is determined according to the size (S103).

  Next, when the predetermined start timing of the target subframe arrives, the base station 20 transmits control information including URLLC resource information in the control channel area (S104), and the timing corresponding to the URLLC resource arrives. Only the eMBB data is transmitted up to the eMBB resource (S105).

  After that, when the timing corresponding to the URLLC resource arrives, the base station 20 transmits the URLLC data using the URLLC resource and the eMBB data using the eMBB resource.

  When the transmission of the URLLC data is completed, the base station 20 transmits only the MBB data using the eMBB resource until the subframe ends (S105).

  FIG. 11 is a sequence diagram showing another example of transmission / reception of transmission data including downlink URLLC data according to the present embodiment. FIG. 11 shows an example of transmitting URLLC data in the subframes of FIGS. 5 and 8 described above. Note that steps S201 to S204 of FIG. 11 are common to those of FIG. 10, and therefore their description is omitted.

  11, after transmitting the control information (S204), the base station 20 transmits the URLLC data by the URLLC resource and the eMBB data by the eMBB resource (S205). When the transmission of the URLLC data is completed, the base station 20 transmits only the MBB data using the eMBB resource until the subframe ends (S206 to S208).

  FIG. 12 is a sequence diagram showing still another example of transmission / reception of transmission data including downlink URLLC data according to the present embodiment. FIG. 12 shows an example of transmitting URLLC data in the subframes of FIGS. 6 and 7 described above. Note that steps S301 to S305 in FIG. 12 are common to those in FIGS. 10 and 11, and therefore their description is omitted.

  In FIG. 12, when the transmission of the URLLC data is completed (S305), the base station 20 transmits only the MBB data by the eMBB resource until the transmission / reception timing of the response (HARQ-ACK / NACK) to the transmission of the URLLC data arrives. (S306 to S307).

  Next, when the transmission / reception timing of the response (HARQ-ACK / NACK) arrives, the base station 20 receives the response (HARQ-ACK / NACK) from the mobile station 30 using the HARQ-ACK / NACK resource (S308). .. When receiving this response, the base station 20 may transmit the MBB data using the eMBB resource other than the HARQ-ACK / NACK resource. Further, when the base station 20 receives the negative response, the base station 20 may retransmit the URLLC data to the mobile station 30 using the HARQ-ACK / NACK resource.

  After receiving the response (HARQ-ACK / NACK) or receiving the response and retransmitting the URLLC data, the base station 20 transmits only the MBB data by the eMBB resource until the subframe ends (S309). ).

  It should be noted that various antenna diversity may be applied between the base station 20 and the mobile station 30 in each of the wireless communication systems of the plurality of embodiments described above. The antenna diversity may be space diversity using a plurality of antennas (antenna ports) spatially separated from each other, or polarization diversity using a plurality of antennas (antenna ports) having mutually different polarizations. ..

  13A, 13B, and 13C are respectively a reception antenna diversity (SIMO diversity), a transmission antenna diversity (MISO diversity), and a transmission / reception antenna diversity (MIMO diversity) applicable to the wireless communication system according to this embodiment. 3 is an explanatory diagram showing an example of FIG.

  In the receiving antenna diversity of FIG. 13A, the mobile station 30 on the receiving side includes a plurality of antennas 31 (1) and 31 (2) having different polarization characteristics or different positions. The mobile station 30 can improve reception quality by selecting or combining the reception signals of the plurality of antennas 31 (1) and 31 (2) that have undergone fading different from each other. Therefore, it is possible to further reduce the delay in wireless transmission of URLLC data and improve the transmission reliability.

  In the transmission antenna diversity of FIG. 13B, the transmission-side base station 20 includes a plurality of antennas 21 (1) and 21 (2) having different polarization positions or different polarization characteristics. The mobile station 30 receives at the antenna 31 the transmission signals transmitted from the plurality of antennas 21 (1) and 21 (2) of the base station 20 and undergoing different fading, and selects or combines the plurality of reception signals. As a result, reception quality can be improved. In particular, when the transmission antenna diversity is applied, it is possible to improve the reception quality without depending on the higher order of the antenna diversity in a small mobile station having a limited antenna installation space.

  The transmission / reception antenna diversity (MIMO diversity) of FIG. 13 (c) is a combination of the reception antenna diversity of FIG. 13 (a) and the transmission antenna diversity of FIG. 13 (b). The base station 20 on the transmitting side and the mobile station 30 on the receiving side each have a plurality of antennas 21 (1), 21 (2) and a plurality of antennas 31 (1), 31 (of different positions or different polarization characteristics. 2) is provided. The mobile station 30 can improve reception quality by selecting or combining a plurality of reception signals that have undergone fading different from each other. In particular, when the transmission / reception antenna diversity is applied, it is possible to further improve the reception quality by acquiring the diversity gain on both the transmitting side and the receiving side.

  13 (b) and 13 (c), as a method of realizing the transmission antenna diversity, for example, a method requiring acquisition of propagation path information on the transmission side and a method of acquiring propagation path information on the transmission side. There is a method to eliminate it.

  In the method that requires acquisition of propagation path information on the transmission side, for example, control of maximum transmission ratio combining, beamforming, or transmission antenna selection is performed based on the propagation path information acquired on the transmission side. In maximum transmission ratio combining, the amplitude or phase of the transmission signal of each antenna port is controlled so that the maximum reception SNR can be obtained on the receiving side. In beamforming, only the phase of the transmission signal of each antenna port is controlled. In the transmission antenna selection, control is performed so that only the transmission antenna port having a high propagation path gain is selected.

  In the method that does not require the propagation path information acquisition on the transmission side, for example, space-time coding (STC, STBC standardized by w-CDMA, etc.) on the transmission side, spatial frequency coding (SFC standardized by LTE, SFBC, etc.) or cyclic delay diversity (eg, “JH Song, JH Kim, HK Song,“ Space-Time Cyclic Delay Diversity Encoded Cooperative Transmissions for Multiple Relays, ”IEICE Trans Commun., Vol.E92-B, No.6, pp. .2320-2323, June 2009 ”), it is possible to acquire diversity gain without acquiring propagation path information on the transmitting side. In particular, when cyclic delay diversity is applied, diversity gain can be obtained without using special spatial coding.

  As described above, according to the present embodiment, the resource allocation amount in the time direction in which low-delay transmission data such as URLLC data is transmitted in the data channel area 420 of the subframe 400 is minimized in the unit of resource element. It is possible to reduce the delay in the transmission of the delayed transmission data.

  Furthermore, by allocating the resources of low-delay transmission data to part or the whole of the system band in the frequency direction, it becomes possible to apply frequency diversity when transmitting low-delay transmission data. Due to the effect of this frequency diversity, it is possible to improve the transmission reliability of low-delay transmission data, suppress the occurrence of retransmission control during wireless transmission, and further reduce the delay in transmission of low-delay transmission data. You can

  Moreover, by allocating the resources in the frequency direction of the low-delay transmission data in the data channel region 420 according to the size of the low-delay transmission data, resource allocation to the low-delay transmission data is performed to the minimum necessary and Since the resource allocation area used for transmission of data other than the transmission data can be increased, frequency utilization efficiency can be improved.

  As described above, according to the present embodiment, it is possible to improve the frequency utilization efficiency and improve the transmission reliability of low-delay transmission data such as URLLC data that requires transmission with a lower delay than normal data such as eMBB data. It is possible to reduce the delay in the transmission of low-delay transmission data.

  Further, according to the present embodiment, it is possible to concentrate the power resources on the resource allocation area in which the low delay transmission data is transmitted under the condition that the average transmission power of the entire system band is maintained at the predetermined power. Therefore, it is possible to improve the transmission reliability of low-delay transmission data and reduce the delay in transmission of low-delay transmission data while maintaining the transmission power of the entire system band at a predetermined power.

  It should be noted that the processing steps and components of the mobile communication system described in this specification can be implemented by various means. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof.

  As for hardware implementation, means such as a processing unit used to implement the above steps and components in a substance (for example, various wireless communication devices, Node Bs, terminals, hard disk drive devices, or optical disk drive devices) One or more application specific ICs (ASICs), digital signal processors (DSPs), digital signal processors (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors , A controller, a microcontroller, a microprocessor, an electronic device, other electronic units designed to perform the functions described herein, a computer, or a combination thereof.

  Also, for firmware and / or software implementations, means such as processing units used to implement the components described above may be programs (eg, procedures, functions, modules, instructions) that perform the functions described herein. , Etc.) may be implemented. In general, any computer / processor readable medium embodying firmware and / or software code, means, such as a processing unit, used to implement the steps and components described herein. May be used to implement. For example, firmware and / or software code may be stored in memory and executed by a computer or processor, eg, at the controller. The memory may be mounted inside the computer or the processor, or may be mounted outside the processor. The firmware and / or software code may be, for example, random access memory (RAM), read only memory (ROM), non-volatile random access memory (NVRAM), programmable read only memory (PROM), electrically erasable PROM (EEPROM). ), A FLASH memory, a floppy disk, a compact disk (CD), a digital versatile disk (DVD), a magnetic or optical data storage device, and the like, even when stored on a computer or processor readable medium. Good. The code may be executed by one or more computers or processors and may cause the computers or processors to perform the functional aspects described herein.

  Further, the medium may be a non-transitory recording medium. In addition, the code of the program may be readable and executable by a computer, a processor, or another device or machine, and its format is not limited to a particular format. For example, the code of the program may be any of source code, object code, and binary code, or may be a mixture of two or more of these codes.

  Also, the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of this disclosure. Therefore, the present disclosure should not be limited to the examples and designs described herein, but should be admitted to the broadest extent consistent with the principles and novel features disclosed herein.

10 wireless communication system 20 base station 21, 21 (1), 21 (2) transmission antenna 30 mobile station 31, 31 (1), 31 (2) reception antenna 80 core network of mobile communication network 210 resource allocation unit 220 transmission unit 400 subframe 410 control channel region 420 data channel region 421 eMBB resource 422 URLLC resource 423 HARQ-ACK / NACK resource 424 HARQ resource other than HARQ-ACK / NACK resource

Claims (16)

A wireless communication device for a mobile communication system,
In the resource allocation region allocated to a part of the system band in the frequency direction of the data channel region of the subframes constituting the radio frame, a transmission unit that transmits low-delay transmission data that requires low-delay communication,
In the frequency direction of the data channel region, the transmission power of the resource allocation region of the low-delay transmission data is set to the resource allocation of the low-delay transmission data under the condition that the average transmission power of the entire system band is maintained at a predetermined power. And a transmission power control unit that controls the transmission power so as to be higher than resource areas other than the area. The wireless communication device according to claim 1,
The wireless communication device, wherein the transmitting unit transmits control information including information defining a resource allocation region of the low delay transmission data in the control channel region. The wireless communication device according to claim 1 or 2,
When using TDD (Time Division Duplex) as the duplex system,
The wireless communication device is characterized in that the data channel area is allocated with a resource area for receiving a retransmission control response for the low-delay transmission data from a destination of the low-delay transmission data. The wireless communication device according to claim 3,
In the frequency direction of the data channel region, the transmission power of the resource allocation region of the retransmission control response is the resource allocation of the retransmission control response under the condition that the average transmission power of the entire system band is maintained at a predetermined power. A wireless communication device characterized by being higher than resource areas other than the area. The wireless communication device according to any one of claims 1 to 4,
The radio communication device, wherein the resource allocation area of the low-delay transmission data is located at a leading portion in the time direction of the data channel area. The wireless communication device according to any one of claims 1 to 4,
The radio communication device, wherein the resource allocation areas of the low delay transmission data are distributed and located at a plurality of locations in the frequency direction of the data channel area. The wireless communication device according to any one of claims 1 to 4,
The radio communication device, wherein the resource allocation areas of the low-delay transmission data are distributed and located at both ends in the frequency direction of the data channel area. The wireless communication device according to any one of claims 1 to 7,
The wireless communication device, wherein the transmission unit transmits a reference signal for demodulating the low-delay transmission data together with the low-delay transmission data in a resource allocation region of the low-delay transmission data. The wireless communication device according to any one of claims 1 to 8,
The wireless communication device, wherein the low-delay transmission data is URLLC (Ultra-Reliable and Low Latency Communications) data.   A wireless communication device on the transmitting side that transmits the low-delay transmission data according to claim 1, and a wireless communication device on the receiving side that receives the low-delay transmission data transmitted from the wireless communication device on the transmitting side. A wireless communication system comprising: The wireless communication system according to claim 10,
The wireless communication device on the reception side is provided with a plurality of radio signals of the low-delay transmission data received at different positions or a plurality of radio signals of different polarizations of the low-delay transmission data. A wireless communication system having an antenna and performing reception antenna diversity for selecting or combining reception signals received by each antenna. The wireless communication system according to claim 10 or 11,
The wireless communication device on the transmitting side is provided with a plurality of radio signals of the low-delay transmission data to be transmitted at different positions or to transmit radio signals of different polarizations of the low-delay transmission data. A wireless communication system having an antenna and performing transmission antenna diversity for selecting or combining transmission signals to be transmitted by each antenna. The wireless communication system according to claim 12,
The wireless communication device on the transmitting side executes the transmitting antenna diversity by performing space-time coding or space-frequency coding on the low-delay transmission data. The wireless communication system according to claim 12,
The wireless communication system, wherein the transmitting antenna diversity is a cyclic delay fiber type. A wireless communication method,
In the resource allocation area allocated to a part of the system band in the frequency direction of the data channel area of the subframes forming the radio frame, transmitting low-delay transmission data that requires low-delay communication,
In the frequency direction of the data channel region, the transmission power of the resource allocation region of the low-delay transmission data is set to the resource allocation of the low-delay transmission data under the condition that the average transmission power of the entire system band is maintained at a predetermined power. Controlling the transmission power so as to be higher than the resource region other than the region, the wireless communication method. A program executed by a computer or a processor provided in a mobile communication wireless communication device,
In the resource allocation area allocated to a part of the system band in the frequency direction of the data channel area of the subframes constituting the radio frame, a program code for transmitting low-delay transmission data that requires low-delay communication,
In the frequency direction of the data channel region, the wireless communication device sets the transmission power of the resource allocation region of the low-delay transmission data to the low transmission power under the condition that the average transmission power of the entire system band is maintained at a predetermined power. A program code for controlling transmission power so as to be higher than a resource area other than the resource allocation area of the delayed transmission data, the program.

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