Wireless communication control method and communication system

Abstract

To improve efficiency of downlink communication, a wireless communication control method includes transmitting, by a transmitting station connected with a first wireless terminal belonging to a first group and a second wireless terminal belonging to a second group different from the first group, a first signal transmitted at a plurality of timings by using a concatenated transmission using an orthogonal cover code, to the first wireless terminal, and transmitting, by the transmitting station, a second signal superimposed with the first signal transmitted at a specific timing among the plurality of timings, to the second wireless terminal.

Description

Technical Field

[0001] This disclosure relates to wireless communication control methods and communication systems. Background Technology

[0002] Within 3GPP (registered trademark), there are standards supporting base stations for Non-Terrestrial Networks (NTN) (e.g., Non-Patent Document 1). Additionally, within 3GPP (registered trademark), there are standards related to Non-Orthogonal Multiple Access (NOMA), a technology that transmits signals by assigning varying transmission power, thereby enabling the transmission of information to multiple users within the same frequency band (e.g., Non-Patent Document 2).

[0003] Existing technical documents

[0004] Non-patent literature

[0005] Non-patent document 1: 3GPP (registered trademark) TR 38.811 V15.4.0 (2020-09)

[0006] Non-patent document 2: 3GPP (registered trademark) TS 38.211 V18.1.0 (2023-12), 6.3.1 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The purpose of this disclosure is to provide a wireless communication control method and communication system that can efficiently implement downlink communication of multiple wireless terminals.

[0009] Methods for solving problems

[0010] One aspect of this disclosure is a wireless communication control method, comprising: transmitting a first signal to a first wireless terminal via a transmitting station connected to a second wireless terminal belonging to a first group and a second wireless terminal belonging to a second group different from the first group, at multiple time intervals, using a cascading transmission of an orthogonal coverage code; and transmitting a second signal to the second wireless terminal via the transmitting station superimposed on the first signal transmitted at a specific time interval among the multiple time intervals.

[0011] Additionally, one aspect of this disclosure is a communication system comprising a transmitting station connected to a first wireless terminal belonging to a first group and a second wireless terminal belonging to a second group different from the first group. The communication system includes circuitry that performs the following processing: transmitting a first signal from the transmitting station to the first wireless terminal at multiple time intervals using a series of orthogonal overlay codes; and transmitting a second signal from the transmitting station to the second wireless terminal superimposed on the first signal transmitted at a specific time interval within the multiple time intervals.

[0012] The methods disclosed herein may include transmitting stations, base stations, satellite stations, wireless terminals, and storage media capable of temporary storage that constitute the communication system involved in this disclosure.

[0013] Invention Effects

[0014] According to this disclosure, it is possible to achieve downlink communication of multiple wireless terminals efficiently. Attached Figure Description

[0015] Figure 1 This is a diagram illustrating an example of the configuration of a communication system according to an embodiment.

[0016] Figure 2 This is a diagram illustrating an example of the configuration of a communication system.

[0017] Figure 3 (A) shows an example of the configuration of a signal transmitted from satellite station 2A. Figure 3 (B) shows an example of the configuration of a signal transmitted from satellite station 2B. Figure 3 (C) shows an example of the configuration of the signal received by terminal 10a. Figure 3 (D) shows an example of the configuration of the signal received by terminal 10b.

[0018] Figure 4 This is an illustration of a demodulation method for signals that utilizes Successive Interference Cancellation (SIC).

[0019] Figure 5 (A) and Figure 5 (B) is an illustration of the demodulation method for the continuous transmission signal using Orthogonal Cover Code (OCC) in terminals 10A and 10B.

[0020] Figure 6 (A) Figure 6 (B) and Figure 6(C) is a diagram illustrating an example of Transmission Power Control (TPC) being performed in a transmission using OCC.

[0021] Figure 7 This is a diagram illustrating an example of the configuration of a wireless device.

[0022] Figure 8 This is a timing diagram illustrating an example of message exchange between a terminal station and a base station.

[0023] Figure 9 This is a timing diagram illustrating the operation of the communication system.

[0024] Figure 10 This is a diagram showing an example of the configuration of a base station.

[0025] Figure 11 This is an explanatory diagram of OCC and transmit power control.

[0026] Figure 12 This is a diagram showing an example of the configuration of a terminal station.

[0027] Figure 13 This is a flowchart illustrating a processing example of a control station.

[0028] Figure 14 This is a flowchart illustrating a processing example of a base station.

[0029] Figure 15 This is a flowchart illustrating a processing example for terminals 10A and 10B.

[0030] Figure 16 This is a flowchart illustrating a processing example for terminals 10a and 10b. Detailed Implementation

[0031] In sixth-generation (6G) mobile communication systems, research has been conducted on methods to ensure communication anywhere on Earth. Satellite communication and other NTN technologies are expected to serve as wireless communication networks for realizing these communication methods. Furthermore, within NTN, not only are dead-zone mitigation measures for terrestrial networks (TN) anticipated, but improvements in reliability when combined with TN, and effective utilization for IoT (Internet of Things) communications, are also anticipated.

[0032] However, the limited frequency range available in NTN necessitates technologies capable of handling the anticipated surge in traffic. Furthermore, the long distance between satellite stations and terminal stations (hereinafter sometimes simply referred to as "terminals") raises concerns about ensuring the desired communication quality at non-line-of-sight (NLOS) terminal stations where high-gain antennas cannot be utilized. In other words, in NTN communication, multiple terminals involved in downlink communication can be categorized into groups with good (marginal) link budgets and groups with poor (no margin) link budgets. Link budget refers to the method of calculating the overall cost (allowable propagation loss) of the link by adding / subtracting all gain factors (gain caused by antennas, amplifiers, coding, etc.) and loss factors (loss caused by cables, free space, fading, thermal noise, etc.) in dB values ​​along the path (link) between the transmitter and receiver in the communication system. Based on the link budget calculation, the arrival distance of radio waves from the base station to the terminal can be determined, which is used for wireless system line design (cell radius, transmit power).

[0033] The communication system involved in the implementation includes a transmitting station connected to a first wireless terminal belonging to a first group and a second wireless terminal belonging to a second group different from the first group. It includes: transmitting a first signal from the transmitting station to the first wireless terminal at multiple time intervals using a series of transmissions employing orthogonal overlay codes; and transmitting a second signal from the transmitting station to the second wireless terminal superimposed on the first signal transmitted at a specific time interval among the multiple time intervals.

[0034] Hereinafter, based on the accompanying drawings, the communication system and wireless communication control method according to the embodiments will be described. The configuration of the embodiments described below is illustrative, and this disclosure is not limited to the configuration of the embodiments. Furthermore, in the embodiments, a 5G (fifth-generation mobile communication system) communication system is illustrated, but the mobile communication method according to this disclosure can be applied to wireless communication methods other than 5G (4G (LTE), 6G, etc.).

[0035] Figure 1 and Figure 2 This is a diagram illustrating an example of the configuration of a communication system. Figure 1 In this system, the communication system comprises multiple base stations 1 controlled by a control station 3. Figure 1 In the example shown, base stations 1A and 1B are illustrated as multiple base stations 1. Base stations 1A and 1B are ground stations. Figure 1 and Figure 2 In the example shown, the control station 3 is illustrated as a device independent of the base station 1, but it is also possible to use any one of the multiple base stations 1 as the control station 3.

[0036] In addition, the communication system includes multiple satellite stations 2 (in pairs) corresponding to multiple base stations 1 (ground stations). Figure 1 The example shown illustrates satellite station 2A operating as a relay station for base station 1A and satellite station 2B operating as a relay station for base station 1B. Satellite station 2A accommodates multiple terminals 10 as subordinate terminals 10. Satellite station 2A transmits (forwards) signals (information and messages) received from each subordinate terminal 10 to base station 1, and forwards signals containing downlink communication data transmitted from base station 10 to each terminal 10. However, it is also possible for satellite station 2 to generate and transmit signals containing data for each terminal 10 according to instructions received from base station 1. Terminal 10 is referred to as UE (User Equipment), and base station 1 is referred to as gNodeB (gNB), etc.

[0037] Satellite station 2A has terminal 10a and terminal 10A as subordinate terminals 10. Satellite station 2B has terminal 10b and terminal 10B as subordinate terminals 10. For example... Figure 2 As shown, terminals 10a, 10A, 10b and 10B are located in the area (interference area) where the coverage area (cell) of satellite station 2A overlaps with the coverage area (cell) of satellite station 2B.

[0038] Multiple terminals 10 are classified into a first group and a second group. Terminals 10A and 10B, which have a good link budget (link budget margin), are classified into the first group. On the other hand, terminals 10a and 10b, which have a poor link budget (no link budget margin), are classified into the second group. Terminals 10A and 10B are examples of "first wireless terminals," and terminals 10a and 10b are examples of "second wireless terminals." Satellite stations 2A and 2B are examples of "transmitting stations." Furthermore, the communication system can be configured with base stations 1A and 1B directly connected to multiple terminals 10; in this case, base stations 1A and 1B are equivalent to "transmitting stations."

[0039] Figure 3 (A) shows an example of the configuration of a signal transmitted from satellite station 2A. Figure 3 (B) shows an example of the configuration of a signal transmitted from satellite station 2B. Figure 3 (C) shows an example of the configuration of the signal received by terminal 10a. Figure 3 (D) shows an example of the signal configuration received by terminal 10b. Given the limitations on the transmission power of satellite stations 2A and 2B, base stations 1A and 1B respectively implement the following processes to generate suitable downlink communication signals.

[0040] First, satellite station 2A (2B) reduces the transmission power of the signal sent to terminal 10A (10B), while increasing the transmission power of the signal sent to terminal 10a (10b) (see reference). Figure 3 (A) and Figure 3 (B)). By widening the transmission power difference in this way, the SIR required for demodulation using SIC in terminal 10 is ensured.

[0041] Second, satellite station 2A (2B) generates a signal based on orthogonal coverage code (OCC) for downlink communication to terminal 10A (10B) belonging to the first group (referred to as OCC relay signal). Regarding the OCC relay signal, relaying is a method of repeatedly sending signals in a predetermined number of relays. That is, in relaying, signals are sent at multiple time intervals (time slots (resource blocks: RBs, 1 RB is 1 time slot on the time axis)) corresponding to the number of relays.

[0042] exist Figure 3 In the examples shown in (A) to (D), the number of consecutive transmissions is 2, and each timing (time slot) is represented by S1 and S2. The signals transmitted in S1 and S2 are multiplied by the OCC (+1 or -1) corresponding to the OCC mode to become states with positive or negative signs.

[0043] For example, such as Figure 3 As shown in (A), in the OCC signal transmitted to terminal 10A, according to the OCC pattern "+1, +1", the signals corresponding to S1 and S2 have a positive sign (+). On the other hand, as Figure 3 As shown in (B), in the OCC relay signal sent to terminal 10B, according to the OCC pattern "+1, -1" different from the above, the signal corresponding to S1 has a + sign, and the signal corresponding to S2 has a negative sign (-). The OCC relay signal is an example of the "first signal". The signal superimposed on the OCC relay signal (NOMA signal) is an example of the "second signal".

[0044] In satellite stations 2A (2B), the signal to terminal 10a (10b) uses the same frequency band as the signal transmitted at multiple transmission timings, i.e., S1 or S2, based on the continuous transmission signal, thus becoming superimposed with the OCC continuous transmission signal. At this time, as described above, this ensures the SIR required for SIC. Here, in satellite station 2A, the signal is superimposed at S1, and in satellite station 2B, the signal is superimposed at S2. Therefore, as... Figure 3 (C) and Figure 3 As shown in (D), a signal destined for terminal 10a is received in S1, and a signal destined for terminal 10b is received in S2. In this way, two time slots can be used to transmit signals to four terminals 10, thus improving frequency utilization efficiency.

[0045] Figure 4 This is an illustration of a demodulation method for signals that utilizes Successive Interference Cancellation (SIC). In NOMA, at the receiving station, multiple signals with different received electric field strengths (received power) within the same frequency band are received. Figure 4 The signal is formed by superimposing signal 1 and signal 2 (as shown in the example). The signal at which the receiving station receives maximum power (the signal is shown in the example). Figure 4 The signal in the middle is signal 1). Next, the receiving station generates a copy of signal 1 and removes signal 1 from the superimposed signal. Thus, signal 2 is obtained.

[0046] In terminal 10a, reception is performed in S1 and S2. Figure 3 The signal shown in (C) is used. Terminal 10a receives a demodulation instruction for the signal under S1 from base station 1A (satellite station 2A). Terminal 10a can obtain the data (downlink user data) sent to terminal 10a by demodulating the superimposed signal under S1 (demodulation and decoding according to the modulation and coding scheme (MSC)). On the other hand, in terminal 10b, the signal received under S1 and S2 is... Figure 3 The signal shown in (D) indicates that terminal 10b receives a demodulation instruction for the signal under S2 from base station 1B (satellite station 2B). Terminal 10b can obtain the data sent to terminal 10b by demodulating the superimposed signal under S2 (according to the demodulation and decoding of the MSC).

[0047] Figure 5 (A) and Figure 5 (B) is an explanatory diagram of the demodulation method for the OCC-transmitted signal in terminals 10A and 10B. Figure 5 In (A), terminal 10A uses... Figure 4 The SIC process, as described, removes the signal destined for terminal 10a from the signal received in S1 and the signal destined for terminal 10b from the signal received in S2. Thus, as residual signals, the OCC transmission signals destined for terminal 10A and terminal 10B remain. Terminal 10A performs S1+S2 processing on the residual signals, that is, it adds the residual signal from S1 to the residual signal from S2, thereby leaving only the OCC transmission signals destined for terminal 10A. By combining these signals, a signal with increased received power destined for terminal 10A is obtained. This signal is then demodulated and decoded according to the MSC to obtain the data destined for terminal 10A. The S1+S2 processing (signal calculation method) is performed according to instructions from base station 1A (satellite station 2A).

[0048] Similarly, in Figure 5 In (B), terminal 10B uses... Figure 4 The SIC process, as described, removes the signals destined for terminal 10a and terminal 10b to obtain a residual signal. Terminal 10A performs S1-S2 processing on the residual signal, that is, subtracts the residual signal from the residual signal of S1, leaving only the OCC transmission signal destined for terminal 10B. By combining these signals, a signal with increased receiving power is obtained for transmission to terminal 10B. This signal is then demodulated and decoded according to the MSC to obtain the data destined for terminal 10B. The S1-S2 processing (signal calculation method) is performed according to instructions from base station 1B (satellite station 2B).

[0049] Figure 6 (A) Figure 6 (B) and Figure 6 (C) is a diagram illustrating an example of transmit power control (TPC) in a transmission using OCC. Figure 6 (A) shows the transmission signal (for downlink communication) of satellite station 2A with transmission power control implemented. Figure 6 (B) shows the transmission signal (for downlink communication) of satellite station 2B with transmission power control implemented. Figure 6 (C) is an illustration of the demodulation process in terminal 10A (10B).

[0050] The transmission power in the OCC continuous transmission signal can vary between timing (time slots) and between terminals 10. Figure 6 In the example shown in (A), the transmission power under S1 is set to be lower than the transmission power under S2. Figure 6 In contrast to (B), terminal 10 can control the transmission power, i.e., set the transmission power, according to instructions from base station 1 (satellite station 2).

[0051] Figure 6 (C) shows the signal received by terminal 10A (10B). Terminal 10A (10B) can remove the signals sent to terminals 10a and 10b via SIC. The signal from the residual signal obtained after removal, for example, the signal with low received power under S1, is amplified to match the received power of the signal under S2, thereby making the received power (signal level) of the signal under S1 and the signal under S2 consistent. Then, terminal 10A (10B) performs... Figure 5 (A) or Figure 5 The processing described in (B) enables the acquisition of signals destined for its own terminal. Then, terminal 10A (10B) demodulates and decodes the signals according to the MSC, and is able to obtain the data subsequently sent to terminal 10A (10B).

[0052] Figure 7This diagram illustrates the hardware configuration of a wireless device applicable to base station 1, satellite station 2, or terminal 10. The wireless device 100 has a CPU 11, main storage device 12, and external devices interconnected via a bus 17, and performs communication and information processing through a computer program. The CPU 11 is also called a processor. The CPU 11 is not limited to a single processor and can also be configured with multiple processors. Furthermore, the CPU 11 may also include a graphics processing unit (GPU), a digital signal processor (DSP), etc. Additionally, the CPU 11 may cooperate with hardware circuits such as a field-programmable gate array (FPGA). As an external device, such as... Figure 7 As shown, external storage device 13, output device 14, operation device (input device) 15 and communication device 16 are illustrated.

[0053] The CPU 11 executes a computer program that is executed in a manner available in the main storage device 12, enabling the wireless device 100 to function as a base station 1 or a terminal 10. The main storage device 12 stores the computer program executed by the CPU 11, data processed by the CPU 11, etc. The main storage device 12 may be a Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Read-Only Memory (ROM), etc. An external storage device 13 may be used, for example, as a storage area supplementing the main storage device 12, storing the computer program executed by the CPU 11, data processed by the CPU 11, etc. The external storage device 13 may be a hard disk drive, a solid-state drive (SSD), etc. Furthermore, the wireless device 100 may be connected to a drive device that serves as a removable storage medium. Examples of removable storage media include Blu-ray discs, Digital Versatile Discs (DVDs), Compact Discs (CDs), flash memory cards, etc.

[0054] Output device 14 is, for example, a display device such as a liquid crystal display or an electroluminescent panel. However, output device 14 may also include a speaker and other sound output devices. Operating device 15 is, for example, a key, button, dial, or a touch panel formed by overlaying a touch sensor on the display. Communication device 16 communicates with external networks such as base station 1 and the Internet, for example, via optical fiber. Communication device 16 includes a wireless communication device (including a transceiver antenna) for wireless communication between base station 1 or satellite station 2 and terminal 10, and a communication device for communication between base station 1 and core network. Communication device 16 may also include communication equipment for connecting to a wireless LAN (Wi-Fi). Communication device 16 may be a single device or a combination of multiple devices.

[0055] The processing performed by the CPU 11 and memory (e.g., main storage device 12) can also be performed by semiconductor devices such as FPGA, CPLD (Complex Programmable Logic Device), ASIC (Application Specific Integrated Circuit), and SoC (System on a Chip), instead of the CPU 11 and memory. The CPU 11 (processor), FPGA, CPLD, ASIC, and SoC are examples of the "circuit" that a wireless device capable of operating as a base station 1 or terminal 10 possesses.

[0056] Figure 8 This is a timing diagram illustrating an example of message exchange between a base station and a terminal. Satellite station 2, which is located between base station 1 and terminal 10, is omitted.

[0057] When the Radio Resource Control (RRC) status of terminal 10 is idle or inactive, base station 1 uses the paging channel (PCH) to send paging information to terminal 10. Figure 8 of <1> Therefore, information exchange is performed between terminal 10 and base station 1 to change the RRC state to the RRC connection state. Figure 8 of <2> ).

[0058] When the RRC state of terminal 10 transitions to the RRC connected state, base station 1, when scheduling requires, uses the Physical Downlink Control Channel (PDCCH) to send a Channel State Information (CSI) request to terminal 10. Figure 8 of <3> Terminal 10 generates information containing Channel State Information (CSI information) and sends it to base station 1 using the Physical Downlink Shared Channel (PDSCH). Figure 8of <4> ).

[0059] Subsequently, control station 3 or base station 1 performs scheduling related to downlink communication with terminal 10. Base station 1 uses PDCCH to send scheduling information to terminal 10. Figure 8 of <5> Base station 1 uses PDSCH to send the data of the downlink communication object (user data) to terminal 10. Figure 8 of <6> Terminal 10 uses the Physical Uplink Control Channel (PUCCH) or the Physical Uplink Shared Channel (PUSCH) to send an ACK or NACK (Negative ACK knowledge) message. Figure 8 of <7> ).

[0060] Upon receiving a NACK, base station 1 uses PDCCH to send retransmission control information to terminal 10. Figure 8 of <8> Afterwards, base station 1 uses PDSCH to send retransmitted data to terminal 10. Figure 8 of <9> ).

[0061] Figure 9 This is a sequence diagram illustrating the operation of the communication system. The control station generates an interference zone ( Figure 2 ) information ( Figure 9 of <1> ), and sent to base stations 1A and 1B ( Figure 9 (1A, 1B).

[0062] When base station 1A wishes to send data (downlink communication) to its subordinate terminals 10A(A) and 10a(α) located in the interference area, it sends the scheduling requests of terminals 10A and 10a, information about terminals 10A and 10a, and information indicating the transmittable power of base station 1A (satellite station 2A) to control station 3 ( Figure 9 (<2A>). The information for terminals 10A and 10a includes CSI, data volume, priority, allowable latency, and information indicating the link budget between each terminal.

[0063] When base station 1B wishes to transmit data (downlink communication) to its subordinate terminals 10B(B) and 10b(β) located in the interference area, it sends the scheduling requests of terminals 10B and 10b, information about terminals 10B and 10b, and information indicating the transmittable power of base station 1A (satellite station 2A) to control station 3. Figure 9 (2B). The information for terminals 10B and 10b includes CSI, data volume, priority, allowable latency, and information indicating the link budget between terminals.

[0064] Control station 3 performs scheduling related to data transmission to terminals 10A and 10a, and terminals 10B and 10b. Figure 9 of <3> Control station 3 sends scheduling information and information about the target terminal (sending permission terminal) among the terminals 10 that have requested scheduling to the base station 1A, as the result of the scheduling. Figure 9 <4A>). The scheduling information includes information on the allocation of radio resources to each licensed transmitting terminal, information on the allocation of transmit power to each licensed transmitting terminal, NOMA information (whether the signal is superimposed with the OCC relay signal), whether OCC is applied, and parameters when OCC is applied (number of relays, OCC mode, etc.).

[0065] In addition, control station 3 sends information about the authorized terminal and scheduling information to base station 1B as the result of the scheduling. Figure 9 <4B>). The scheduling information includes information on the allocation of radio resources to each licensed transmitting terminal, information on the allocation of transmit power to each licensed transmitting terminal, NOMA information (whether the signal is superimposed with the OCC relay signal), whether OCC is applied, and parameters when OCC is applied (number of relays, OCC mode, etc.).

[0066] Based on information indicating the authorized terminal and scheduling information, base station 1A uses PDCCH to send control information such as resource allocation to terminals 10A and 10a. Figure 9 <5A>). Based on the information indicating the terminal authorized to transmit and the scheduling information, base station 1B uses PDCCH to send control information such as resource allocation to terminals 10B and 10b. Figure 9 <5B>). Afterwards, base station 1A uses PDSCH to send downlink communication target data to terminals 10A and 10b ( Figure 9 <6A>). Additionally, base station 1B uses PDSCH to send downlink communication target data to terminals 10B and 10a (…). Figure 9 (<6B>). Control station 3, base station 1A, satellite station 2A, base station 1B, and satellite station 2B operate synchronously in a manner that enables them to share wireless resources.

[0067] Figure 10 This is a diagram showing an example of the configuration of base station 1. Figure 7 The wireless device 100 shown is capable of functioning as a device by executing a program via CPU 11. Figure 9 It operates based on the configuration of base station 1 shown.

[0068] exist Figure 10In this system, base station 1 includes a radio protocol control unit 201 with a scheduler 202, a PDCCH / PCH control unit 203, a radio unit 204, an antenna 205, and a control unit 206. Satellite station 2 includes at least a radio wave transceiver antenna, a radio unit, and a mechanism for amplifying (correcting signal waveforms) the transmitted and received radio waves.

[0069] The scheduler 202 can communicate with the control station 3, using interference area information from the control station 3 and the location information of its subordinate terminals 10 to determine the terminals 10 (terminals 10A and 10a) located in the interference area. The scheduler 202 sends scheduling requests from each terminal 10 to the control station 3. Figure 9 <2A> Figure 9 <2B>). Receive information from control station 3 regarding the sending license terminal and its scheduling information ( Figure 9 <4A> Figure 9 (of <4B>).

[0070] The scheduler 202 provides control signals for each terminal 10, including radio resource indication (information indicating the allocation of radio resources), OCC specification information (number of consecutive transmissions (=2, 4, 8, 16, ...), OCC mode, and transmit power control content), and NOMA information (information on whether signals are superimposed).

[0071] The PDCCH / PCH control unit 203 processes the transmission of paging information to the terminal 10 using the PCH, and maps control signals from the radio protocol control unit 201 to the PDCCH and transmits them to the terminal 10. The radio unit 204 converts the output signals (baseband signals) of the PDCCH / PCH control unit 203 and control unit 206 into radio signals (radio waves). The antenna 205 is a transceiver antenna, transmitting radio waves from the radio unit 204 and transmitting received radio waves back to the radio unit 204. The radio unit 204 processes the conversion of radio waves into baseband signals. Channel state information (CSI) and ACK / NACK messages from the baseband signals are sent to the scheduler 202.

[0072] Scheduler 202 receives data (transmission data) from the upper layer for downlink communication. The transmission data is converted into a transmission data signal in the radio protocol control unit 201 according to MCS modulation and coding, and provided to the control unit 206. The control unit 206 transmits data from satellite station 2A (2B) according to control signals (radio resource indication, OCC designation, NOMA information). Figure 2 A ( Figure 2 In the signal method shown in B), the data to be transmitted to each terminal 10 is mapped to the PDSCH (signal generation). Additionally, the control unit 206 can also control the transmission power according to TPC information under the control of the wireless unit 204.

[0073] Figure 11 This is an explanatory diagram of OCC and transmit power control. In Figure 11 The example illustrates four OCC and transmission power indication modes when the number of consecutive transmissions is 4. In modes 1 to 4, the OCC symbols are different from each other. Additionally, in modes 1 to 4, an example is shown where the transmission power in the second transmission (transmission index number = 2) is reduced by -3dB compared to the normal transmission power (difference = -3dB). In the first, third, and fourth transmissions (transmission index numbers = 1, 3, and 4), the difference from the normal transmission power is 0dB. Information indicating the transmission power value for each (timing) transmission can also be transmitted as a transmission power indication.

[0074] Figure 12 This is a diagram showing an example of the configuration of terminal 10. Figure 7 The wireless device 100 shown operates as a terminal 10 comprising a wireless protocol control unit 101, a PDCCH / PCH control unit 102, a wireless unit 103, an antenna 104, a PUCCH / PUSCH control unit 105, and a PDSCH control unit 106 by executing a program by a CPU 11.

[0075] exist Figure 12 In this configuration, antenna 104 is a transceiver antenna for transmitting and receiving radio waves. The radio unit 103 performs the conversion between radio waves (radio signals) and baseband signals. The PDCCH / PCH control unit 102 acquires paging information mapped to the PCH, control information mapped to the PDCCH (including scheduling information), and retransmission control information, and transmits them to the radio protocol control unit 101. The radio protocol control unit 101 can output information for transitioning the RRC state to a connected state and CSI information. The information for transitioning the RRC state to a connected state and the CSI information are mapped to the PUCCH in the PUCCH / PUSCH control unit 105 and transmitted from antenna 104 via radio unit 103. ACK / NACK messages transmitted from radio protocol control unit 101 are also transmitted from antenna 104 via PUCCH / PUSCH control unit 105 and radio unit 103.

[0076] The wireless signal containing the object data of downlink communication received by antenna 104 is provided to PDSCH control unit 106 via wireless unit 103. PDSCH control unit can perform demodulation using SIC, demodulation using OCC, and demodulation and decoding using MCS according to scheduling information provided by wireless protocol control unit 101. Thus, the raw data is obtained and transmitted from wireless protocol control unit 101 to the upper layer.

[0077] Figure 13This is a flowchart illustrating a processing example of control station 3. Control station 3, for example, has... Figure 7 The wireless device 100 shown has the same hardware configuration (however, the communication device is a wired communication device), and can execute programs by the CPU 11. Figure 13 The processing is shown.

[0078] In step S201, control station 3 reports the interference area. Figure 9 <1A> and <1B>). In step S202, control station 3 receives scheduling requests and terminal information from base stations 1A and 1B (<1A> and <1B>). Figure 9 (2A and 2B).

[0079] In step S203, control station 3 allocates wireless resources and power, and schedules the data transmission to each terminal 10. Figure 9 of <3> In step S204, information on the transmitting license terminal and scheduling information are sent to base stations 1A and 1B. Figure 9 (4A and 4B).

[0080] Figure 14 This is a flowchart illustrating a base station processing example. In step S01, base station 1 detects the generation of data destined for downlink communication with terminal 10. In step S02, base station 1 determines whether the RRC state of terminal 10 is connected. If the RRC state is determined to be connected, the process proceeds to step S03; otherwise, the process proceeds to step S04.

[0081] In step S03, base station 1 determines whether terminal 10 has a valid CSI. If it is determined that there is a valid CSI, the process proceeds to step S06; otherwise, the process proceeds to step S05.

[0082] In step S04, base station 1 performs a transition to the RRC connection state, causing the process to proceed to step S06. In step S05, base station 1 performs a process to obtain CSI from terminal 10, causing the process to proceed to step S06.

[0083] In step S06, base station 1 sends a scheduling request to control station 3. Figure 9 <2A> Figure 9 (2B). In step S07, base station 1 uses the transmission permission terminal information and scheduling information received from control station 3 to schedule radio resources and power allocation related to downlink communication with terminal 10.

[0084] In step S08, base station 1 uses PDCCH to send control information (radio resource allocation, OCC indication, transmit power indication, etc.). In step S09, PDSCH is used to send signals (OCC transmission signal, NOMA signal) after the data to terminal 10 is modulated according to MCS.

[0085] In step S09, base station 1 determines whether it has received an ACK message from terminal 10. If it determines that an ACK message has been received, Figure 14 If the processing ends, then proceed with the retransmission control (step S11).

[0086] Figure 15 This is a flowchart illustrating a processing example for terminals 10A and 10B. In step S101, terminal 10A (10B) in the RRC connected state waits to receive data (receive data for downlink communication). Furthermore, if the RRC state of terminal 10A (10B) is not the RRC connected state, a transition process to the RRC connected state is performed (steps S111 to S113).

[0087] In step S102, terminal 10A (10B) performs PDCCH reception, that is, receives information required for demodulation such as radio resource allocation and OCC indication. In step S103, terminal 10A (10B) performs PDSCH reception, that is, receives data from downlink communication objects.

[0088] In step S104, terminal 10A (10B) performs interference removal of the NOMA signal based on SIC (refer to...). Figure 4 , Figure 5 (A) Figure 5 (B)). In step S105, terminal 10A (10B) performs OCC demodulation (refer to...). Figure 5 (A) Figure 5 (B)

[0089] In step S106, terminal 10A (10B) performs demodulation according to MCS to obtain demodulated data. In step S107, terminal 10A (10B) determines whether there are errors in the demodulated data. If it is determined that there are no errors in the demodulated data, the demodulated data is sent to the upper layer; otherwise, data retransmission control is performed (step S108).

[0090] Figure 16 This is a flowchart illustrating processing examples for terminals 10a and 10b. Figure 16 In the processing example shown, without Figure 15 At this point, in steps S104 and S105 shown, and Figure 15 The treatment is different, but apart from that, it is the same as Figure 15The processing is the same. In step S106, terminal 10a (10b) demodulates the signal mapped to the radio resource (RB) specified by the radio resource allocation based on the MCS, thereby obtaining demodulated data.

[0091] According to the communication system and wireless communication control method involved in the implementation, a transmitting station (satellite station 2A(22B)) connected to a first wireless terminal (terminal 10A(10B)) belonging to a first group and a second wireless terminal (terminal 10a(10b)) belonging to a second group different from the first group transmits a first signal (OCC transmission signal) to the first wireless terminal (terminal 10A(10B)) at multiple timings (e.g., time slots) using orthogonal coverage code transmission (OCC transmission). Additionally, the transmitting station (satellite station 2A(2B)) can transmit a second signal (NOMA signal) superimposed on the first signal transmitted at a specific timing among the multiple timings to the second wireless terminal (terminal 10a(10b)). In this case, the transmission power of the first signal (OCC transmission signal) superimposed on the second signal (NOMA signal) can be configured such that the transmission power of the second signal (NOMA signal) is less than the transmission power of the first signal (NOMA signal). Furthermore, the transmission power of the second signal and the first signal superimposed on the second signal can be determined by having a specified signal-to-interference power ratio (SIR) between the second signal (NOMA signal) and the first signal (OCC relay signal) superimposed on the second signal. This ensures that the signal transmitted from satellite station 2A (2B) to terminals 10A and 10a (10B and 10b) reliably has the SIR required for SIC. Additionally, the transmitting station (satellite station 2A (2B)) can control (increase or decrease) the transmission power at multiple timings. From the viewpoint of obtaining the above advantages, the communication system does not need to have a series of base station 1A (base station 1A, satellite station 2A, terminals 10A and 10a) and a series of base station 1B (base station 1B, satellite station 2B, terminals 10B and 10b), only one series is required.

[0092] However, communication systems can be like Figure 1 and Figure 2 As shown, the configuration is as follows: a second transmitting station (satellite station 2B), which is different from the first transmitting station (satellite station 2A) that serves as the transmitting station, transmits a third signal (OCC transmission signal) based on orthogonal coverage code to a first wireless terminal (terminal 10B) connected to the second transmitting station (satellite station 2B) at multiple time intervals.

[0093] The second transmitting station (satellite station 2B) can also transmit a fourth signal (NOMA signal) superimposed on the third signal (OCC relay signal) transmitted at a time other than a specific time among multiple timed transmissions to a second wireless terminal (terminal 10b) connected to the second transmitting station (satellite station 2B). This allows for the sharing of radio resources (bandwidth) between transmitting stations, improving frequency utilization efficiency. In this case, the transmission power of the third signal superimposed with the fourth signal can be lower than the transmission power of the fourth signal itself. Alternatively, the transmission power of the fourth signal and the first signal superimposed with the fourth signal can be determined by a method that ensures a predetermined signal-to-interference power ratio between the fourth signal and the third signal superimposed with the fourth signal. The second transmitting station can control the transmission power at multiple timed transmissions.

[0094] The communication system described in this embodiment employs a configuration where the link budget value of the first wireless terminal (terminals 10A and 10B) belonging to the first group is better than the link budget value of the second wireless terminal (terminals 10a and 10b) belonging to the second group. However, the basis for grouping the first and second groups can also be other than the link budget value. Furthermore, the communication system described in this embodiment illustrates a case where the first and second wireless terminals are located in an overlapping area (interference area) between the coverage areas of the first and second transmitting stations. However, it is also possible to transmit downlink communication signals consisting of superimposed OCC and NOMA signals to multiple terminals located in coverage areas outside the interference area of ​​satellite station 2A (2B).

[0095] The above-described implementation is merely an example, and this disclosure can be appropriately modified and implemented without departing from its main intent. Furthermore, the processes and methods described in this disclosure can be freely combined and implemented as long as they do not create technical contradictions.

[0096] Furthermore, a process described as being performed by one device can also be executed by multiple devices. Alternatively, a process described as being performed by different devices can also be executed by one device. In a computer system, the hardware configuration (server configuration) used to implement each function can be flexibly changed.

[0097] This disclosure can also be implemented by providing a computer program, which incorporates the functions described in the above embodiments, to a computer, which then reads and executes the program using one or more processors. Such a computer program can be provided to the computer via a non-transitory computer-readable storage medium connectable to the computer's system bus, or via a network. Non-transitory computer-readable storage media include, for example, any type of disk suitable for storing electronic commands, such as a disk (floppy disk, hard disk drive (HDD), etc.), an optical disk (CD-ROM, DVD, Blu-ray disc, etc.), a read-only memory (ROM), a random access memory (RAM), an EPROM, an EEPROM, a magnetic card, flash memory, or an optical card.

Claims

1. A wireless communication control method, comprising: A transmitting station connected to a first wireless terminal belonging to a first group and a second wireless terminal belonging to a second group different from the first group sends a first signal to the first wireless terminal, which is transmitted at multiple time intervals by using a series of transmissions using an orthogonal coverage code. as well as The transmitting station transmits a second signal to the second wireless terminal, which is superimposed on the first signal transmitted at a specific time among the plurality of time intervals.

2. The wireless communication control method according to claim 1, wherein, The transmission power of the first signal superimposed with the second signal is less than the transmission power of the second signal.

3. The wireless communication control method according to claim 2, wherein, The transmission power of the second signal and the first signal superimposed with the second signal is determined in such a way that the second signal and the first signal superimposed with the second signal have a specified signal-to-interference power ratio.

4. The wireless communication control method according to claim 1, wherein, The transmitting station controls the transmission power under the multiple timing conditions.

5. The wireless communication control method according to claim 1, wherein, It also includes: a second transmitting station, different from the first transmitting station, transmitting a third signal based on a cascading signal using an orthogonal coverage code to the first wireless terminal connected to the second transmitting station during the plurality of timings.

6. The wireless communication control method according to claim 5, wherein, The second transmitting station transmits a fourth signal, superimposed on the third signal transmitted at a time other than the specific time among the plurality of time intervals, to the second wireless terminal connected to the second transmitting station at a time other than the specific time among the plurality of time intervals.

7. The wireless communication control method according to claim 6, wherein, The transmission power of the third signal superimposed with the fourth signal is less than the transmission power of the fourth signal.

8. The wireless communication control method according to claim 7, wherein, The transmission power of the superimposed fourth signal and the first signal of the fourth signal are determined in such a way that the fourth signal and the third signal superimposed on the fourth signal have a predetermined signal-to-interference power ratio.

9. The wireless communication control method according to claim 6, wherein, The second transmitting station controls the transmission power under multiple timed conditions.

10. The wireless communication control method according to claim 1, wherein, The link budget value involved by the first wireless terminal belonging to the first group is better than the link budget value involved by the second wireless terminal belonging to the second group.

11. The wireless communication control method according to claim 5, wherein, The first wireless terminal and the second wireless terminal are located in the overlapping area of ​​the coverage area of ​​the first transmitting station and the coverage area of ​​the second transmitting station.

12. A communication system, It includes a transmitting station, which is connected to a first wireless terminal belonging to a first group and a second wireless terminal belonging to a second group different from the first group. The communication system includes circuitry that performs the following processing: The transmitting station transmits a first signal to the first wireless terminal via a series of timed transmissions using orthogonal coverage codes; and The transmitting station transmits a second signal to the second wireless terminal, which is superimposed on a first signal transmitted at a specific time among the plurality of time intervals.

13. The communication system according to claim 12, wherein, The transmission power of the first signal superimposed with the second signal is less than the transmission power of the second signal.

14. The communication system according to claim 13, wherein, The transmission power of the second signal and the first signal superimposed with the second signal is determined in such a way that the second signal and the first signal superimposed with the second signal have a specified signal-to-interference power ratio.

15. The communication system according to claim 12, wherein, The transmitting station controls the transmission power under the multiple timing conditions.

16. The communication system according to claim 12, wherein, It also includes a second sending station, which is different from the first sending station that serves as the sending station. The second transmitting station transmits a third signal based on a cascading transmission using an orthogonal coverage code to the first wireless terminal belonging to the first group connected to the second transmitting station during the plurality of timings.

17. The communication system according to claim 16, wherein, The second transmitting station transmits a fourth signal, superimposed on the third signal transmitted at a time other than the specific time among the plurality of time intervals, to a second wireless terminal belonging to the second group connected to the second transmitting station at a time other than the specific time among the plurality of time intervals.

18. The communication system according to claim 17, wherein, The transmission power of the third signal superimposed with the fourth signal is less than the transmission power of the fourth signal.

19. The communication system according to claim 18, wherein, The transmission power of the fourth signal and the first signal superimposed on the fourth signal is determined by having a predetermined signal-to-interference power ratio between the fourth signal and the third signal superimposed on the fourth signal.

20. The communication system according to claim 19, wherein, The second transmitting station controls the transmission power under multiple timed conditions.

Images