Transmission control method and information processing device

Abstract

To provide a transmission control method capable of preferably controlling the delay at a sending station that performs consecutive transmissions.SOLUTION: The transmission control method is a method of controlling multiple sending stations that are connected with a receiving station of the wireless communication partner in a manner of non-orthogonal multiple access manner. Each of the multiple sending stations is capable of sending the same signal to the receiving station predetermined successively times a predetermined period by consecutive transmission. An information processor executes the steps of: acquiring information that represents the codeword length used by each of the multiple sending stations for the consecutive transmission; and assigning the transmission power that ensures the required power difference between sending stations to each of the multiple sending stations so that the shorter the codeword length, the higher the transmission power.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present disclosure relates to a transmission control method and an information processing device. [Background technology]

[0002] The mobile communications standardization organization 3GPP (Third Generation Partnership Project) has set coverage enhancement as one of the topics for Release 17. The conference is examining technologies that will enable communications that meet desired communication requirements, regardless of the distance from the base station, even when there is a large propagation loss between the base station and the terminal.

[0003] Background art related to the present disclosure includes, for example, a technique for continuously transmitting the same signal and integrating the same signal at a receiving station to improve the signal-to-noise ratio (SNR) at the receiving station (e.g., Non-Patent Document 1). Also, there is a technique that enables multiple terminals connected to a base station via Non-orthogonal Multiple Access (NOMA) to transmit data in the same time period using the same frequency band (e.g., Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TR 38.830, Study on NR coverage enhancements (Release 17), December 2020 [Non-Patent Document 2] M. Moriyama, T. Takizawa, M. Oodo, H. Tezuka, and F. Kojima, “Experimental Evaluation of a Novel Up-link NOMA System for IoT communication Equipping Repetition Transmission and Receive Diversity,” IEICE Trans. Commun., Vol.E102 -B, No.8, pp1467-1476 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a technique that enables suitable delay control for a transmitting station that performs continuous transmission. [Means for solving the problem]

[0006] One aspect of the present disclosure is a transmission control method for multiple transmitting stations that are non-orthogonally multiple-connected to a receiving station that is a wireless communication partner, and each of the multiple transmitting stations is capable of transmitting the same signal to the receiving station a predetermined number of times in a predetermined period by continuous transmission, in which an information processing device acquires information indicating a code word length used by each of the multiple transmitting stations for the continuous transmission, and allocates to each of the multiple transmitting stations a transmission power that is required between the transmitting stations and that can ensure a received power difference at the receiving station such that the shorter the code word length, the higher the received power at the receiving station.

[0007] Another aspect of the present disclosure is an information processing device that includes a control unit, and for a plurality of transmitting stations that are non-orthogonally multiple connected to a receiving station of a wireless communication partner, and each of the plurality of transmitting stations is capable of transmitting an identical signal to the receiving station a predetermined number of times in a predetermined period by continuous transmission, the control unit executes the following operations: acquiring information indicating a code word length used by each of the plurality of transmitting stations for the continuous transmission; and allocating to each of the plurality of transmitting stations a transmission power required between the transmitting stations that can ensure a reception power difference at the receiving station such that the transmission power is higher as the code word length is shorter.

[0008] Another aspect of the present disclosure is a plurality of transmitting stations that are non-orthogonally multiple-accessed to a receiving station of a wireless communication partner, each transmitting the same signal to the receiving station a predetermined number of times in a predetermined period by continuous transmission. A transmission control method for a first transmitting station included in a plurality of transmitting stations capable of transmission, the first transmitting station transmitting a code word length to be used for the continuous transmission to the receiving station, receiving information indicating a transmission power to be used for the continuous transmission allocated based on the code word length, and performing the continuous transmission using the transmission power.

[0009] Other aspects of the present disclosure may include a wireless communication system including the above-mentioned multiple transmitting stations and receiving stations, a program for causing a computer to operate as the above-mentioned transmitting station, receiving station, or information processing device, a non-transitory storage medium having the program recorded thereon, and the like. Effect of the Invention

[0010] According to the present disclosure, suitable delay control is possible for a transmitting station that performs continuous transmission. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1A is a diagram showing a first configuration example of a wireless communication system, and FIG. 1B is a diagram showing a second configuration example of a wireless communication system. [Diagram 2] FIG. 2 is a diagram illustrating an example of a radio frame applied to a radio communication system. [Diagram 3]FIG. 3 is an explanatory diagram of power multiplexing and interference suppression and cancellation techniques. [Figure 4] FIG. 4 is a diagram showing an example of continuous transmission in a wireless communication system. [Diagram 5] FIG. 5 is a diagram illustrating an example of the hardware configuration of the base station and the terminal. [Figure 6] FIG. 6 is a block diagram showing an example of the configuration of a terminal. [Figure 7] FIG. 7 is a block diagram showing an example of the configuration of a base station. [Figure 8] FIG. 8 is a flowchart showing an example of processing in the base station. [Figure 9] FIG. 9 is a flowchart illustrating details of step S001 in FIG. [Figure 10] FIG. 10 is a flowchart showing the details of step S002 in FIG. [Figure 11] FIG. 11 is a flowchart showing the details of step S021 in FIG. [Figure 12] FIG. 12 illustrates an example of an improved continuous transmission performed in a wireless communication system. [Figure 13] FIG. 13 is a diagram showing an experimental example relating to continuous transmission. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Wireless communication system configuration> Fig. 1 is a diagram showing a first configuration example of a wireless communication system according to an embodiment. Fig. 1B is a diagram showing a second configuration example of the wireless communication system. The wireless communication system according to the first configuration example includes a base station 1 and a plurality of terminals 2 (#0 to #K-1, K is a natural number including 0) that communicate wirelessly with the base station 1. The base station 1 is an example of a receiving station, and the plurality of terminals 2 are an example of a plurality of transmitting stations.

[0013] Each of the multiple terminals 2 is called UE (User Equipment). Each of the multiple terminals 2 includes an antenna 20, a wireless device 2a connected to the antenna 20, and a control device 2b connected to the wireless device 2a. The control device 2b acquires (receives) data from a sensor 3 or the like. The control device 2b also controls the wireless device 2a to transmit a data signal or a control signal to the base station 1, or to receive a control signal or the like from the base station 1. The wireless device 2a converts a signal to be transmitted, including a data signal and a control signal, into a wireless signal and radiates (transmits) it from the antenna 20. The wireless station 2a also converts the wireless signal received from the antenna 20 into a signal format that can be handled by the control device 2b. The number of antennas 20 may be one or more. The terminal 2 has two or more antennas, and communicates with the base station 1 using MIMO (multiple-input and multiple-output). tput) communication may be performed.

[0014] The base station 1 includes one or more antennas 10, a radio 1a connected to the antenna 10, and a control device 1b connected to the radio 1a. The radio 1a and the control device 1b have the same functions as the radio 2a and the control device 2b. The control device 2b can transmit data received from the terminal 2 to a server 4 or the like. The control device 1b is an example of an information processing device (computer). The information processing device may be included in the base station 1, or may be a terminal device (such as a server) different from the base station 1 (independent from the base station 1). In other words, a terminal device such as a server may be configured to calculate the number of consecutive transmissions to multiple terminals 2 and the transmission power to be used each time, and notify (transmit) the same to each terminal 2.

[0015] According to the wireless communication system, for example, data (such as IoT (Internet of Things) data) acquired from a sensor 3 at each of the multiple terminals 2 can be accumulated in a server 4 via a base station 1. Data from the server 4 can also be transmitted to each of the multiple terminals 2 via the base station 1. The terminals 2 may be fixed terminals or mobile terminals. The mobile terminals may be portable terminals or in-vehicle terminals. The in-vehicle terminals may be terminals mounted on the vehicle or terminals installed in the vehicle.

[0016] As shown in the second configuration example of FIG. 1B, a base station 1A having two or more distributed base stations and a control device 1b may be applied instead of the base station 1. The distributed base station has an antenna 10 and a wireless device 1a, and is called an RRH (Remote Radio Head: wireless unit). The control device 1b to which the distributed base station is connected is called a BBU (Base Band Unit: signal processing unit). In the following description, the base station 1 having the first configuration example will be described.

[0017] In the first and second configuration examples, the base station 1 and each of the multiple terminals 2 communicate (transmit and receive signals) using a downlink (downlink: DL) and an uplink (uplink: UL). The DL is a line from the base station 1 to the terminals 2, and includes a control channel (control CH) used for transmitting (notifying) control signals. On the other hand, the UL is a line from the terminals 2 to the base station 1, and includes a control CH and a shared channel (shared CH) used for transmitting data (user data). The shared CH is also called a data channel.

[0018] <radio frame> The UL signal and the DL signal are transmitted using a time domain allocated by time division multiplexing. FIG. 2 is a diagram showing an example of a radio frame applied to a radio communication system. In FIG. 2, the radio frame has a predetermined time length. The radio frame length is 10 ms in 5G, but may be shorter or longer than 10 ms. The radio frame is divided into a plurality of subframes. In 5G, the subframe length is specified to be 1 ms, and the radio frame is divided into 10 subframes. However, the subframe length and the number of divisions are not limited to the example of 5G. The subframe may be further divided into two or more slots (slot length: 500 μm). As shown in FIG. 2, each subframe of the radio frame is allocated to DL or UL. In the example of FIG. 2, DL and UL are allocated so that one DL is followed by four ULs. However, such allocation can be changed. The slots in the subframe to which the UL is allocated are equally divided, and a reference signal (RS) is mapped to the first half, and a data signal (DS) is mapped to the second half. However, the arrangement of the reference signal and the data signal in one slot can be changed as appropriate.

[0019] The reference signal is a signal known to the receiving station (base station 1) and is used to estimate the channel (propagation path or communication path) of the wireless signal. The data signal is a signal that is modulated and coded according to a predetermined MCS (Modulation and Coding Scheme) for user data. This is the signal.

[0020] <Characteristics of wireless communication systems> The wireless communication system has the following features in uplink communication of data signals. First, the wireless communication system in this embodiment employs configured grant (CG). As shown in FIG. 2, in UL communication, the frequency channel and slot available for CG are notified to terminal 2 in advance, a different reference signal is prepared for each terminal 2, and the reference signal is transmitted together with the data signal, which is the payload, to realize CG. CG can eliminate communication delays associated with the procedure in which a terminal obtains a grant, which is permission to communicate, from a base station.

[0021] Secondly, in a wireless communication system, wireless signals (reference signals and data signals) are transmitted from a plurality of terminals 2 using the same frequency domain and the same time domain (slot) by non-orthogonal multiple access. At this time, each terminal 2 transmits a wireless signal with a transmission power specified by the base station 1 so that a desired difference in received power occurs between the terminals 2 at the base station 1. NOMA can reduce the waiting time of signal transmission. However, it is necessary for the base station 1 to suppress and remove inter-terminal interference from each terminal 2.

[0022] Fig. 3 is an explanatory diagram of power multiplexing and interference suppression / removal technology. The diagram on the left side of Fig. 3 shows a schematic diagram of the received power at the base station 1 of radio signals transmitted from terminals A, B, and C, which are examples of multiple terminals 2. In this example, the data signals received from terminals A, B, and C are in a state of being superimposed (superimposed signal) with the received power at the base station 1. Then, the power difference D1 between the received power at terminal A and the received power at terminal B, and the power difference D2 between the received power at terminal B and the received power at terminal C are each equal to or greater than the received power difference (required power difference ΔP) between terminals 2 at the base station 1, which is required for suitable interference suppression / removal.

[0023] The base station 1 obtains the propagation path characteristics based on the reference signal, and uses these propagation path characteristics to demodulate and decode the superimposed signal, thereby obtaining data from the terminal A. The inventors of the present application call the wireless communication system including the above-mentioned CG, UL communication using NOMA, and interference suppression and removal technology (SIC, etc.) STABLE (Simultaneous Transmission Access Boosting Low-latency). However, the transmission (continuous transmission) control method according to the present application is as follows: This is applicable to wireless communication systems that use NOMA other than STABLE.

[0024] The Successive Interference Cancellation (SIC) algorithm is used to suppress and remove interference from the signal of terminal A from the superimposed signal. SIC is a method to detect a signal with a high received signal strength indicator (RSSI). This is an algorithm that sequentially judges the signals of each terminal in order and removes them. The SIC algorithm uses an estimate of the communication path (propagation path) characteristics between terminal 2 and base station 1, using a reference signal specific to terminal 2. In other words, the SIC algorithm uses the estimate of the propagation path characteristics to reproduce (generate) the signal (called a replica signal) transmitted from terminal 2 (terminal A) with the strongest received signal among the superimposed signals, and subtracts it from the superimposed signal. This removes interference caused by the data signal from terminal A from the superimposed signal (see the middle diagram in Figure 3).

[0025] The superimposed signal from which the data signal from terminal A has been removed can be demodulated and decoded using the propagation path characteristics based on the reference signal of terminal B to obtain the data from terminal B. Furthermore, a replica signal of the data signal transmitted from terminal B is generated using the SIC algorithm and subtracted from the superimposed signal, thereby removing the interference from the data signal from terminal B and leaving the data signal transmitted from terminal C (see the diagram on the right side of Figure 3). The data from terminal C can be obtained by demodulating and decoding the signal using the propagation path characteristics based on the reference signal of terminal C. Data from C can be obtained.

[0026] <Repetition> Furthermore, in the wireless communication system, each of the multiple terminals 2 can perform continuous transmission. Continuous transmission is the continuous and repeated transmission of the same signal at a predetermined period (e.g., every slot). The signal transmitted from the terminal 2 by continuous transmission is received and integrated by the base station 1. The received signals are added together through integration, thereby increasing the SNR and improving the reception quality (SINR or propagation loss).

[0027] In the case of continuous transmission, the codeword length (i.e., coding rate) used to generate data signals may be the same among multiple terminals 2. On the other hand, continuous transmission may be performed in a situation where each of multiple terminals 2 independently determines the coding length to be used, and different coding rates are mixed. Mixing of codeword lengths occurs, for example, when the MCS used by terminals 2 is different.

[0028] The purpose of continuous transmission is to increase the SNR through integration of the signals received by continuous transmission, thereby improving the SINR. For this reason, it is conceivable to arrange multiple terminals 2 in ascending order of propagation loss, and allocate transmission power to multiple terminals 2 so that the smaller the propagation loss, the higher the received power at the base station.

[0029] FIG. 4 is a diagram showing an example of continuous transmission. In FIG. 4, it is assumed that there are five terminals 2 (K-1=5) performing UL communication in NOMA. The identification information (user ID) of each of the five terminals 2 is "1", "2", "3", "4" and "5". The terminals "1" to "5" are numbered in order of the largest propagation loss between them and the base station 1. The codeword lengths of the terminals "1" to "5" are not the same. In the example of FIG. 4, the codeword lengths used by the terminals "1" and "5" during continuous transmission are such that four slots are used to transmit one continuous transmission of data signals. The codeword length used by the terminal "2" during continuous transmission is such that two slots are used to transmit one continuous transmission of data signals. The codeword length used by each of the terminals "3" and "4" during continuous transmission is such that one slot is used to transmit one continuous transmission of data signals.

[0030] As shown in FIG. 4, when the codeword length of the terminals (in the example of FIG. 4, “2”, “3”, and “4”) located below the terminal “1” with the maximum reception power of the base station is shorter than the codeword length of the terminal “1”, the following problem occurs. That is, since four slots are required for receiving the data signal of the terminal “1”, the minimum delay for generating a replica signal of the terminal “1” by SIC and removing the signal from the terminal “1” is four slots. However, in the reception of four slots, each of the terminals “2”, “3”, and “4” has already completed reception for performing normal demodulation and decoding. Nevertheless, the minimum delay for the terminal “1” is awaited, and there is a problem that the delay time until the decoding results for these terminals are obtained is long. In the following description, the details of the wireless communication system and the transmission control method of the transmitting station that can solve at least the above-mentioned problem will be described.

[0031] <Hardware configuration> Fig. 5 is a diagram showing an example of the hardware configuration of the base station 1 and the terminal 2. In Fig. 5, the base station 1 includes M antennas 10 (10-1 to 10-M (M is a natural number)) shown in Fig. 1A, a wireless device (wireless processing device) 1a, and a control device 1b. The control device 1b includes a processor 11, a storage device (memory) 12, an internal interface 13, and a network interface 14 for communicating with other base stations, etc.

[0032] The processor 11 is also called a Central Processing Unit (CPU) or a Microprocessor Unit (MPU). The processor 11 is not limited to a single processor. The processor 11 may have a multi-processor configuration. The processor 11 may have a multi-core configuration with a single physical CPU connected via a single socket. The processor 11 may include an arithmetic device of various circuit configurations such as a Digital Signal Processor (DSP) or a Graphics Processing Unit (GPU). The processor 11 may also cooperate with an integrated circuit (IC), other digital circuits, or an analog circuit. The integrated circuit is, for example, an LSI, an Application Specific Integrated Circuit (ASIC), or a Programmable Logic Device (PLD). The PLD is, for example, a Field-Programmable The processor 11 is, for example, a microcontroller ( The processor 11 may be called an MCU, a system-on-a-chip (SoC), a system LSI, a chip set, etc. The processor 11 is an example of a control unit.

[0033] The storage device 12 stores a sequence of instructions (computer program) executed by the processor 11, or data processed by the processor 11. The internal interface (internal IF) 13 is a circuit that connects various peripheral devices to the processor 11.

[0034] The network interface (NW-IF) 14 is a communication device that allows the base station 1 to access a network to which other base stations are connected. The network to which other base stations are connected is also called a backhaul. The backhaul is, for example, a wired network using optical communication.

[0035] The wireless device 1a includes a transmitter for transmitting a wireless signal and a receiver for receiving a wireless signal, and is connected to antennas 10 (10-1, . . . , 10-M). The wireless device 1a may have M systems of transmitters and receivers, the number of which is the same as the number of antennas.

[0036] 5, the terminal 2 includes an antenna 20, a radio device (radio processing device) 2a, and a control device 2b. The control device 2b includes a processor 21, a storage device (memory) 22, an internal interface (internal IF) 23, and a network interface (NW-IF) 24 for communicating with other base stations, etc.

[0037] The processor 21, the storage device 22, the internal IF 23, the NW-IF 24, and the wireless device 2a have similar functions to those of the processor 11, the storage device 12, the internal IF 13, the NW-IF 14, and the wireless device 1a.

[0038] <Device configuration> Fig. 6 is a block diagram showing a configuration example of a terminal. When the processor 21 shown in Fig. 5 executes a program stored in the storage device 22, the terminal 2 operates as a device including an RS unit 210 and a DS unit 220. The RS unit 210 includes an RS generating unit 211. The RS generating unit 211 generates a reference signal.

[0039] The DS unit 220 includes an encoding unit 221 and a modulation unit 222. The encoding unit 221 performs a predetermined error correction coding on input data (user data). The error correction coding is, for example, turbo coding, but other coding formats may also be used. Furthermore, for example, CRC (Cyclic Redundancy Check) coding may be performed before the turbo coding.

[0040] The modulation unit 222 digitally modulates the encoded data to generate a data signal. The digital modulation method is, for example, Quadrature Amplitude Modulation (QAM), Phase Shift Keying (PSK), etc. The encoding and modulation method is determined based on the MPEG encoding method set in the terminal 2. Follow CS.

[0041] The terminal 2 further includes a multiplexer (multiplexing unit) 202. The output terminal of the multiplexer 202 is connected to the antenna 20. After outputting the reference signal, the multiplexer 202 switches to outputting the data signal, thereby connecting one slot's worth of reference signal and data signal to the antenna 20. Note that a cyclic prefix (CP) is inserted in front of each of the reference signal and the data signal to compensate for the influence of delayed waves. In the case of continuous transmission, a signal section can be provided for this purpose. In the case of continuous transmission, the data signal is generated so that the same data signal is transmitted the number of continuous transmissions (N times) designated by the base station 1. Alternatively, the generated data signal may be duplicated and transmitted the number of continuous transmissions (N times).

[0042] <Base station configuration> Fig. 7 is a diagram showing a configuration example of the base station 1. The processor 11 of the base station 1 executes a program stored in the storage device 12, so that the base station 1 operates as a device having the blocks shown in Fig. 7. As shown in Fig. 7, the base station 1 includes an antenna 10, a demultiplexer 101, an RS unit 110, and a DS unit 120. The demultiplexer 101 transmits a reference signal in a signal received from the antenna 10 to an integrator 111 of the RS unit 110 and transmits a data signal to an integrator 121 of the DS unit 120 by a switching operation. At this time, the CPs added to the reference signal and the data signal are removed.

[0043] The integrator 111 adds up the reference signals received by the continuous transmission to obtain a reference signal with sufficient received signal power. The channel estimator 112 uses the integrated reference signal to calculate an estimate of the channel characteristics (channel vector). This estimate is used for demodulation processing in the demodulator 123 and for generating a replica signal.

[0044] The DS unit 120 includes an integration unit 121, a replica removal unit 122, a demodulation unit 123, a decoding unit 124, and a replica generation unit 126. The integration unit 121 calculates the number of consecutive transmissions N assigned to the target terminal 2 (terminal k). k By adding together the data signals (of N slots), the SNR of the received signal is increased, thereby improving the SINR.

[0045] The replica removal unit 122 subtracts the replica signal generated by the replica generation unit 126 from the integrated received signal (superimposed signal). The demodulation unit 123 uses the estimated value of the communication channel characteristics from the communication channel estimation unit 112 to separate the data signal of the target terminal 2 (terminal 2 having the largest transmission power value among the terminals that have transmitted the superimposed signal) and demodulates the separated data signal. The decoding unit 123 decodes the coding performed by the coding unit 221 of the terminal 2 and outputs the original data.

[0046] The replica generation unit 126 includes an encoding unit 127, a modulation unit 128, and a multiplication unit 129. The encoding unit 127 and the modulation unit 128 perform the encoding and digital modulation performed in the terminal 2 on the data output from the decoding unit 124. The multiplication unit 129 multiplies the modulated data by an estimate of the communication path characteristics between the target terminal 2 (terminal 2 that is the source of the decoded data) and the base station 1. This generates a replica signal. The replica signal is supplied to the replica removal unit 122.

[0047] <Calculation of transmission power based on codeword length> Fig. 8 is a flowchart showing an example of processing in the base station 1. The processing shown in Fig. 8 is performed, for example, by the processor 11 (control device 1b) of the base station 1. For example, when multiple terminals 2 transmit data to the base station 1, the processing is started when the base station 1 receives a transmission request for a data signal transmitted from the terminals 2 through a UL control channel. However, the start trigger is not limited to the above. Input parameters for the processor 11 are as follows: Terminal ID (user ID) k: k takes values ​​ranging from a minimum of “0” to a maximum of “K-1”. ·Maximum transmission power P max,UE : Maximum transmission power allowed for terminal 2 Required power difference ΔP: The difference in received power between terminals at the base station required for optimal interference suppression and cancellation.

[0048] The input parameters are stored, for example, in the storage device 12. However, the input parameters may be stored in a location other than the storage device 12. Furthermore, the processor 11 may obtain some or all of the input parameters from a network.

[0049] In step S001, the processor 11 calculates the propagation loss L between the base station 1 and the terminal 2 for K terminals 2 (terminals k: 0 to K−1) that perform UL communication by NOMA. k The processor 11 also measures the codeword length C k Get the.

[0050] In step S002, the processor 11 calculates a codeword length C k The transmission power value P based on k The output parameters at the end of step S003 are as follows: The transmission power P specified for each of K terminals 2 (terminals with terminal IDs k=0 to K-1) k

[0051] In step S003, the base station 1 transmits information including the output parameters to each of the multiple terminals 2 via the DL control channel. At this time, the base station 1 can include information indicating the number of continuous transmissions, the continuous transmission start slot, and the frequency channel used for the continuous transmission in the information transmitted to the terminal 2. These pieces of information may be transmitted to the terminal 2 using a channel other than the DL control channel.

[0052] 9 is a flowchart illustrating the details of step S001 in FIG. 8. In step S011, the processor 11 sets the transmission power for each terminal 2 to a transmission power value p k,UE and transmit a control signal. This instruction is transmitted, for example, through a DL control channel.

[0053] In step S012, the processor 11 controls each terminal 2 to set the transmission power value p k,UE The received signal strength r of the control signal transmitted by k,BS The control signal is transmitted, for example, via a UL control channel.

[0054] In step S013, the processor 11 calculates the transmission power value p k,UE Received signal strength r k,BS By subtracting k In step S003, when the base station 1 has a plurality of antennas 10, for example, the average value of the path loss related to the received signal of each antenna 10 is calculated as the path loss L k It can be used as:

[0055] In step S014, the processor 11 calculates the codeword length C that is included in the control signal and is used by each terminal 2 when transmitting the codewords. k The information indicating the above (for example, MCS) is acquired and stored in the storage device 22 or the like.

[0056] FIG. 10 is a flowchart illustrating the details of step S002 in FIG. 8. In step S021, the processor 11 k is sorted in ascending order (here, in ascending order from shortest to oldest), k(i) is determined as the terminal station ID.

[0057] 11 is a flowchart for explaining the details of step S021. In step S031, the processor 11 transmits K terminals 2 to the terminals 2 with a codeword length of C k Arrange in ascending order of length.

[0058] In step S032, the processor 11 determines the codeword length C k In the result of sorting the K terminals 2 in ascending order of the codeword length, the processor 11 judges whether there are two or more terminals of the same rank (terminals having the same codeword length) among the K terminals 2. k In the same codeword length C k If it is determined that the same codeword length exists, the process proceeds to step S033, and if not, the process proceeds to step S034.

[0059] In step S033, the terminals with the same rank are grouped according to the propagation loss L k By raising the ranking of terminal 2 with smallest propagation loss, transmission power is allocated so that the received power at base station 1 is high, thereby improving the SNR.

[0060] In step S034, a terminal ID k(i) is assigned to each of the terminals k whose ranks have been determined without any ties. k(i) is a function that decreases as the value of i increases. Therefore, the higher the rank based on the codeword length, the smaller the value of k(i) will be.

[0061] An example is shown below. For example, there are four terminals k (k=0 to 3), and the codeword length C k Suppose the value of is: C0=5, C1=1, C2=2, C3=1 Furthermore, assume that the path loss Lk of terminal k is as follows: L0=90, L1=80, L2=85, L3=75

[0062] In the above example, C k The order based on this is C1=C3, C2, C0. However, since C1=C3, the magnitude of the propagation loss L1 and the propagation loss L3 are compared. As a result, C3, which has a lower propagation loss (larger loss), is placed higher than C1. Therefore, the final order is C3, C1, C2, C0. And the value of k(i) for terminal k=0 to 3 is, for example, as follows: The value is: k(i=0)=3,k(i=1)=1,k(i=2)=2,k(i=3)=0,

[0063] 10, in step S22, the processor 11 sets the value of the argument i to 0. In step S023, the processor 11 determines whether the current value of i is 0 (the minimum value of i). If it is determined that the value of i is 0, the process proceeds to step S024, and if not, the process proceeds to step S025.

[0064] In step S024, the processor 11 determines the transmission power value P k(i) Maximum transmission power P max,UE As a result, the transmission power of terminal k(0) in the above example, i.e., terminal k=3, is set to the maximum transmission power. Note that the maximum transmission power P max,UE Instead of Pmax,UE A lower desired value may be used, and then the process proceeds to step S026.

[0065] When the process proceeds to step S025, the processor 11 determines the transmission power of the terminal k(i). Value P k(i) is determined to be the smaller of a first and second value shown below. First value: Maximum transmission power P max,UE Second value: Power value P of terminal k(i-1) k(i-1) From the above, the propagation loss L k(i) and the propagation loss L k(i-1) The difference between the two and the required power difference ΔP is subtracted. The second value is smaller than the first value. The second value is equal to or larger than the required power difference ΔP so that a sufficient power difference can be obtained between the terminals.

[0066] In step S026, the processor 11 judges whether the current value of i is K-1 (the maximum value of i). If it is judged that the value of i is K-1, the flow of FIG. 10 ends, and if not, the process proceeds to step S027. In step S027, i In this way, the value of the transmission power P k(i) Decided As a result, transmission power that ensures a power difference of at least the required power difference ΔP is allocated to terminal k.

[0067] FIG. 12 is a diagram showing an example of improved continuous transmission executed in a wireless communication system. When the processes according to the flows shown in FIG. 8 to FIG. 13 are performed for the terminals 2 with terminal IDs "1" to "5" shown in FIG. 4, the following occurs. That is, when the codeword length C k In ascending order of propagation loss L k The terminals "1" to "5" are arranged in order (including adjustment based on the 3), and an initial power value is assigned to each of them (steps S023 to S027). Therefore, the order of terminals "1" to "5" is changed to "3" → "4" → "2" → "1" → "5" in the order of shortest codeword length, and transmission power is assigned in the order from highest to lowest. As a result, the reception power of the base station increases in the above order, resulting in the state shown in FIG. 13. Here, among terminals "1" to "5", terminal "3" with the shortest codeword length is positioned at the top. Since the codeword length of terminal "3" is one slot, the delay required for demodulating and decoding the signal from terminal "3" is one slot length. In this way, in this embodiment, it is possible to shorten the minimum delay at which terminals "1" to "5" can start demodulating and decoding the signal after starting continuous transmission in sync with the timing (continuous transmission start slot). In other words, it is possible to perform a suitable delay control for terminal "3" that performs continuous transmission. In addition, since terminal “3” has a short code length, it is expected that favorable demodulation and decoding results (required BLER (Block Error Rate)) can be obtained early by setting a high transmission power, and it is also possible to stop the continuous transmission of terminal “3” early.

[0068] 13 is a diagram showing an example of an experiment relating to continuous transmission using the wireless communication system according to the embodiment. The environment in the example of the experiment is as follows. ·ISD (Inter-Site Distance: distance between base stations): 1732m - NLOS (Non Line Of Sight) environments Maximum transmit power: 23dBm Number of antennas at base station 1: 2 Randomly select 3 types corresponding to MCS=1,3,5 Error correction code: LDPC (Low Density Parity Check)

[0069] 13, multiple user IDs (terminal 2) "1" to "6" are arranged in ascending order of propagation loss. The vertical axis of the graph represents the number of slots required to start demodulation and decoding.

[0070] In contrast, the blocks on the right side are arranged in order based on the codeword length (including adjustment using propagation loss). In this case, the maximum transmission power among multiple terminals 2 performing continuous transmission is assigned to the terminal 2 with the shortest codeword length, so the minimum delay required for demodulating and decoding the signal from that terminal 2 is shortened. In this way, it is possible to perform suitable delay control for terminals 2 performing continuous transmission.

[0071] <Effects of the embodiment> The wireless communication system according to the embodiment includes a plurality of transmitting stations (terminals 2) that are non-orthogonally connected to a receiving station (base station 1) that is a wireless communication partner (FIGS. 1A and 1B). Each of the plurality of terminals 2 can transmit the same signal to the base station 1 a predetermined number of times in a predetermined period (number of slots) by continuous transmission (FIG. 4).

[0072] An information processing device included in the base station 1, that is, a control device 1b including a processor 11, acquires information indicating the codeword length used for continuous transmission by each of the multiple terminals 2 (S014 in FIG. 9). In addition, the processor 11 acquires information indicating the codeword length in the base station that can secure the required power difference ΔP required between the terminals 2. Transmission power is allocated to each of the multiple terminals 2 so that the shorter the codeword length, the higher the received power. As a result, the maximum received power among the multiple terminals 2 is allocated to the terminal 2 with the shortest codeword length. Therefore, the minimum delay (required number of slots) required to start demodulation and decoding for that terminal 2 can be shortened compared to the case where higher transmission power is allocated the greater the propagation loss. As a result, suitable delay control can be performed for terminals 2 that perform continuous transmission.

[0073] In the embodiment, the processor 11 or the control device 1b allocates transmission power to two or more terminals 2 having the same codeword length included in the terminals 2 such that the higher the reception quality (propagation loss) at the base station 1, the higher the reception power (S083 in FIG. 11, FIG. 10). In this way, the transmission power is allocated so that the reception power at the base station 1 of the terminal 2 having a small propagation loss is high, thereby improving the reception quality (SINR or error rate).

[0074] Furthermore, in the embodiment, the processor 11 or the control device 1b can obtain information indicating the codeword length transmitted from each of the multiple terminals 2 to the base station 1. For example, as shown in Fig. 9, the processor 11 or the control device 1b (base station 1) instructs the multiple terminals 2 to transmit signals at a predetermined transmission power (specified transmission power) (S011). Then, the processor 11 or the control device 1b can obtain information indicating the codeword length in the signals transmitted from the multiple terminals 2 to the base station 1 in accordance with this instruction (S014).

[0075] In the embodiment, the processor 11 or the control device 1b calculates the reception quality (path loss L k ) can be obtained. This allows the acquisition of the codeword length and the measurement of the propagation loss to be performed simultaneously (efficiently). Note that the acquisition of the codeword length and the measurement of the propagation loss may be performed separately.

[0076] In the embodiment, the processor 11 or the control device 1b can perform the following. That is, the processor 11 or the control device 1b determines the order of the multiple terminals 2 so that the shorter the codeword length, the higher the terminal 2 is ranked (FIG. 11). In addition, the processor 11 or the control device 1b allocates transmission power to the terminal k(0) that is ranked highest among the multiple terminals 2. On the other hand, the maximum transmit power (P max,UE Then, the processor 11 or the control device 1b assigns the highest terminal k(0) The transmission power to be assigned to each of the remaining terminals excluding max,UE In the lower power range, calculation is performed so that the required power difference ΔP is ensured in the received power at the base station (S025 in FIG. 10). This makes it possible to allocate to each terminal 2 ranked second and below a transmission power that has a power difference suitable for SIC while enabling an improvement in SINR.

[0077] Furthermore, in the embodiment, the processor 11 or the control device 1b can transmit information including transmission power allocated to the multiple terminals 2 to the multiple terminals 2. The information can be transmitted via the UL control channel or other (S003 in FIG. 8). The terminal 2 can receive the information and set the transmission power to be used for the continuous transmission. Furthermore, the terminal 2 may receive information indicating the number of continuous transmissions, the timing to start continuous transmission, and the frequency channel to be used together with the information indicating the transmission power.

[0078] Furthermore, in the embodiment, each of the multiple terminals 2 performing continuous transmission is an example of a "first transmitting station", and the terminal 2 can receive information indicating the transmission power allocated by the base station 1 to the multiple terminals 2 such that the transmission power is higher as the codeword length becomes shorter.

[0079] The terminal 2 receives an instruction from the base station 1, includes information indicating a codeword length to be used for the continuous transmission in a signal corresponding to the instruction, and transmits the signal corresponding to the instruction to the base station 1. At this time, the terminal 2 can transmit a signal according to the instruction with the transmission power designated by the base station 1.

[0080] The processes and means described in this disclosure can be freely combined and implemented as long as no technical contradiction occurs. Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Alternatively, a process described as being performed by different devices may be executed by one device. In a computer system, the hardware configuration (server configuration) by which each function is realized can be flexibly changed.

[0081] The present disclosure can also be realized by supplying a computer program implementing the functions described in the above embodiments to a computer, and having one or more processors of the computer read and execute the program. Such a computer program may be provided to the computer by a non-transitory computer-readable storage medium connectable to the system bus of the computer, or may be provided to the computer via a network. Non-transitory computer-readable storage media include, for example, any type of disk, such as a magnetic disk (floppy disk, hard disk drive (HDD), etc.), an optical disk (CD-ROM, DVD disk, Blu-ray disk, etc.), a read-only memory (ROM), a random access memory (RAM), an EPROM, an EEPROM, a magnetic card, a flash memory, an optical card, and any type of medium suitable for storing electronic instructions. [Explanation of symbols]

[0082] 1...Base station 1a, 2a... Radio (radio processing device) 1b, 2b...Control device 2. Terminal 10,20... Antenna 11,21...Processor 12,22...Storage device 13,23... Internal Interface 14,24...Network Interface 101···Switch 110...RS section 111,121...Integrator part 112 Communication channel estimation unit 122 Replica removal section 123 Demodulation section 124 Decoding section 126... Replica generation unit 127...Encoding section 128 Modulation section 129... Multiplication section

Claims

1. A transmission control method for a plurality of transmitting stations that are connected in a non-orthogonal multiple access manner to a receiving station of a wireless communication partner, each of which is capable of transmitting an identical signal to the receiving station a predetermined number of times in a predetermined period by continuous transmission, comprising: An information processing device, acquiring information indicating a codeword length used by each of the plurality of transmitting stations for the continuous transmission; allocating transmission power required between the transmitting stations, capable of ensuring a difference in reception power at the receiving station, to each of the plurality of transmitting stations such that the shorter the codeword length is, the higher the reception power at the receiving station is; A transmission control method for performing the above.

2. The information processing device allocates transmission power to two or more transmitting stations having the same codeword length included in the plurality of transmitting stations such that the higher the reception quality at the receiving station, the higher the reception power at the receiving station. The transmission control method according to claim 1 .

3. The information processing device acquires information indicating the codeword length transmitted from each of the plurality of transmitting stations to the receiving station.

3. A transmission control method according to claim 1 or 2.

4. the information processing device instructs the plurality of transmitting stations to transmit signals at a predetermined transmission power; Obtaining information indicating the codeword length included in the signals transmitted from the plurality of transmitting stations to the receiving station in accordance with the instruction 3. A transmission control method according to claim 1 or 2.

5. The information processing device acquires a reception quality at the receiving station of a signal transmitted to the receiving station. The transmission control method according to claim 4.

6. The information processing device determines the order of the plurality of transmitting stations so that the shorter the codeword length, the higher the transmitting station is, and in allocating the transmission power, allocates the maximum allocable transmission power to the transmitting station ranked highest among the plurality of transmitting stations, and calculates the transmission power to be allocated to each of the remaining transmitting stations excluding the highest transmitting station, within a range of power lower than the maximum transmission power, so that a difference in reception power at the receiving station is secured. The transmission control method according to any one of claims 1 to 5.

7. The information processing device transmits information including transmission powers allocated to the plurality of transmitting stations to the plurality of transmitting stations. The transmission control method according to any one of claims 1 to 6.

8. A control unit is included. The control unit, with respect to a plurality of transmitting stations that are non-orthogonally multiple-accessed with a receiving station of a wireless communication partner, each of which is capable of transmitting the same signal to the receiving station a predetermined number of times in a predetermined period by continuous transmission, acquiring information indicating a codeword length used by each of the plurality of transmitting stations for the continuous transmission; allocating transmission power required between the transmitting stations, capable of ensuring a difference in reception power at the receiving station, to each of the plurality of transmitting stations such that the shorter the codeword length is, the higher the reception power at the receiving station is; An information processing device that executes the above.

9. The control unit allocates transmission power to two or more transmitting stations having the same codeword length included in the plurality of transmitting stations such that the higher the reception quality at the receiving station, the higher the reception power at the receiving station. The information processing device according to claim 8.

10. The control unit acquires information indicating the codeword length transmitted from each of the plurality of transmitting stations to the receiving station.

10. The information processing device according to claim 8 or 9.

11. the control unit instructs the plurality of transmitting stations to transmit signals at a predetermined transmission power; Obtaining information indicating the codeword length included in the signals transmitted from the plurality of transmitting stations to the receiving station in accordance with the instruction 10. The information processing device according to claim 8 or 9.

12. The information processing device according to claim 11 , wherein the control unit acquires a reception quality at the receiving station of a signal transmitted to the receiving station.

13. The control unit determines the order of the plurality of transmitting stations so that the shorter the codeword length, the higher the transmitting station is, and in allocating the transmission power, allocates the maximum allocable transmission power to the transmitting station ranked highest among the plurality of transmitting stations, and calculates the transmission power to be allocated to each of the remaining transmitting stations excluding the highest transmitting station, within a range of power lower than the maximum transmission power, so that a difference in reception power at the receiving station is secured. The information processing device according to claim 8 .

14. The control unit transmits information including transmission powers allocated to the plurality of transmitting stations to the plurality of transmitting stations. The information processing device according to claim 8 .

15. The receiving station is included The information processing device according to claim 8 .

16. A transmission control method for a first transmitting station included in a plurality of transmitting stations that are non-orthogonally multiple-connected to a receiving station of a wireless communication partner, each of the transmitting stations being capable of transmitting an identical signal to the receiving station a predetermined number of times in a predetermined period by continuous transmission, comprising: The first transmitting station, transmitting a codeword length to be used in the continuous transmission to the receiving station; receiving information indicating a transmission power to be used for the continuous transmission, the transmission power being allocated based on the codeword length; performing the continuous transmission using the transmission power; A transmission control method for performing the above.

17. The first transmitting station receives information indicating a transmission power allocated to the receiving station for the plurality of transmitting stations such that the transmission power is higher as the codeword length is shorter. The transmission control method according to claim 16.

18. the first transmitting station receiving an indication from the receiving station; including information indicating a codeword length to be used in the continuous transmission in a signal corresponding to the instruction; transmitting a signal in response to the instruction to the receiving station; The transmission control method according to claim 16 or 17, further comprising the steps of:

19. The first transmitting station transmits a signal according to the instruction at a transmission power designated by the receiving station. The transmission control method according to claim 18.

20. The first transmitting station receives information indicating a start timing of the continuous transmission, a frequency channel to be used for the continuous transmission, and a number of the continuous transmissions. A transmission control method according to any one of claims 16 to 19.

Images