US-12621044-B2 - Communication system, control apparatus, relay station, and communication method

Abstract

A communication system includes a first communication station, a second communication station, a relay station to non-regenerative-relay communications between the first communication station and the second communication station, and a control apparatus. The relay station relay-transmits a relay wave with a relay power value of such a limit as to fulfill a second condition when a transmission wave being transmitted from the first communication station and being relay-transmitted by the relay station fulfills a first condition about a signal-to-interference noise power ratio (SINR) and when the relay wave being relay-transmitted by the relay station and reaching the second communication station fulfills the second condition about the signal-to-interference noise power ratio (SINR) and the relay power value in the relay station.

Inventors

• Kenichi Takizawa

Assignees

• TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date

20260505

Application Date

20231101

Priority Date

20221102

Claims (20)

1. 1 . A communication system comprising: a first communication station; a second communication station; a relay station to non-regenerative-relay communications between the first communication station and the second communication station; and a control apparatus, the relay station relay-transmitting a relay wave with a relay power value of such a limit as to fulfill a second condition when a transmission wave being transmitted from the first communication station and being relay-transmitted by the relay station fulfills a first condition about a signal-to-interference noise power ratio (SINR) and when the relay wave being relay-transmitted by the relay station and reaching the second communication station fulfills the second condition about the signal-to-interference noise power ratio (SINR) and the relay power value in the relay station.
2. 2 . The communication system according to claim 1 , wherein the first condition is that the signal-to-interference noise power ratio (SINR), given when the transmission wave transmitted by the first communication station is relay-transmitted by the relay station, satisfies a first reference value, and the second condition is that the relay power value to relay-transmit the relay wave, in a case where the signal-to-interference noise power ratio (SINR) given when the relay wave being relay-transmitted by the relay station is received by the second communication station satisfies a second reference value, is within a range of allowable transmission power in the relay station.
3. 3 . The communication system according to claim 2 , wherein the control apparatus, when the relay wave fulfills the second condition, notifies the relay station of the relay power value of the relay wave fulfilling the second condition and information for specifying the first reference value, and the relay station relay-transmits the relay wave with the notified relay power value when the signal-to-interference noise power ratio (SINR) given upon relay-transmitting the transmission wave by the relay station satisfies the first reference value.
4. 4 . The communication system according to claim 2 , wherein the control apparatus notifies the relay station of information for determining the first condition and information for determining the second condition, and the relay station: calculates the relay power value to relay-transmit the relay wave when the signal-to-interference noise power ratio (SINR) given upon the second communication station's receiving the relay wave being relay-transmitted by the relay station satisfies the second reference value; and relay-transmits the relay wave when the signal-to-interference noise power ratio (SINR) given upon relay-transmitting the transmission wave by the relay station satisfies the first reference value, and when the calculated relay power value of the relay wave is within the range of the allowable transmission power in the relay station.
5. 5 . The communication system according to claim 2 , wherein the relay station notifies the control apparatus of non-fulfillment notification when the signal-to-interference noise power ratio (SINR) given upon relay-transmitting the transmission wave by the relay station does not satisfy the first reference value, and the control apparatus, when receiving the non-fulfillment notification, instructs the first communication station to increase power of the transmission wave within the range of the allowable transmission power in the first communication station.
6. 6 . The communication system according to claim 1 , wherein the first condition is that a transmission power value of the transmission wave, when the signal-to-interference noise power ratio (SINR) given upon the relay station's relay-transmitting the transmission wave being transmitted by the first communication station satisfies the first reference value, is within the range of the allowable transmission power in the first communication station, and the second condition is that a relay power value to relay-transmit the relay wave, when the signal-to-interference noise power ratio (SINR) given upon the second communication station's receiving the relay wave being transmitted by the first communication station satisfies the second reference value, is within the range of the allowable transmission power in the relay station.
7. 7 . The communication system according to claim 6 , wherein the control apparatus, when the transmission wave fulfills the first condition and when the relay wave fulfills the second condition, notifies the first communication station of the transmission power value of the transmission wave fulfilling the first condition, and notifies the relay station of the relay power value of the relay wave fulfilling the second condition, the first communication station transmits the transmission wave with the transmission power value that fulfills the first condition, and the relay station relays the relay wave with the relay power value that fulfills the second condition.
8. 8 . The communication system according to claim 1 , wherein the first condition is that the transmission wave coming from the first communication station, when the signal-to-interference noise power ratio (SINR) given upon the relay station's relay-transmitting the transmission wave being transmitted by the first communication station and upon the second communication station's receiving the relay-transmitted transmission wave satisfies the second reference value, is transmitted within the range of the allowable transmission power in the first communication station, and the second condition is that the relay power value to relay-transmit the relay wave, when the signal-to-interference noise power ratio (SINR) given upon the second communication station's receiving the relay power value of the relay wave being relay-transmitted by the relay station satisfies the second reference value, is within the range of the allowable transmission power in the relay station.
9. 9 . A control apparatus configured to: control a first communication station, a second communication station, and a relay station to non-regenerative-relay communications between the first communication station and the second communication station; and cause the relay station to relay-transmit a relay wave with a relay power value of such a limit as to fulfill a second condition when a transmission wave being transmitted from the first communication station and being relay-transmitted by the relay station fulfills a first condition about a signal-to-interference noise power ratio (SINR) and when the relay wave being relay-transmitted by the relay station and reaching the second communication station fulfills the second condition about the signal-to-interference noise power ratio (SINR) and the relay power value in the relay station.
10. 10 . The control apparatus according to claim 9 , wherein the first condition is that the signal-to-interference noise power ratio (SINR), given when the transmission wave transmitted by the first communication station is relay-transmitted by the relay station, satisfies a first reference value, and the second condition is that the relay power value to relay-transmit the relay wave, in a case where the signal-to-interference noise power ratio (SINR) given when the relay wave being relay-transmitted by the relay station is received by the second communication station satisfies a second reference value, is within a range of allowable transmission power in the relay station.
11. 11 . The control apparatus according to claim 10 , wherein the control apparatus, when the relay wave fulfills the second condition, notifies the relay station of the relay power value of the relay wave fulfilling the second condition and information for specifying the first reference value, and the relay station relay-transmits the relay wave with the notified relay power value when the signal-to-interference noise power ratio (SINR) given upon relay-transmitting the transmission wave by the relay station satisfies the first reference value.
12. 12 . The control apparatus according to claim 10 , wherein the control apparatus notifies the relay station of information for determining the first condition and information for determining the second condition, and the relay station: calculates the relay power value to relay-transmit the relay wave when the signal-to-interference noise power ratio (SINR) given upon the second communication station's receiving the relay wave being relay-transmitted by the relay station satisfies the second reference value; and relay-transmits the relay wave when the signal-to-interference noise power ratio (SINR) given upon relay-transmitting the transmission wave by the relay station satisfies the first reference value, and when the calculated relay power value of the relay wave is within the range of the allowable transmission power in the relay station.
13. 13 . The control apparatus according to claim 10 , wherein the relay station notifies the control apparatus of non-fulfillment notification when the signal-to-interference noise power ratio (SINR) given upon relay-transmitting the transmission wave by the relay station does not satisfy the first reference value, and the control apparatus, when receiving the non-fulfillment notification, instructs the first communication station to increase power of the transmission wave within the range of the allowable transmission power in the first communication station.
14. 14 . The control apparatus according to claim 9 , wherein the first condition is that a transmission power value of the transmission wave, when the signal-to-interference noise power ratio (SINR) given upon the relay station's relay-transmitting the transmission wave being transmitted by the first communication station satisfies the first reference value, is within the range of the allowable transmission power in the first communication station, and the second condition is that a relay power value to relay-transmit the relay wave, when the signal-to-interference noise power ratio (SINR) given upon the second communication station's receiving the relay wave being transmitted by the first communication station satisfies the second reference value, is within the range of the allowable transmission power in the relay station.
15. 15 . The control apparatus according to claim 14 , wherein the control apparatus, when the transmission wave fulfills the first condition and when the relay wave fulfills the second condition, notifies the first communication station of the transmission power value of the transmission wave fulfilling the first condition, and notifies the relay station of the relay power value of the relay wave fulfilling the second condition, the first communication station transmits the transmission wave with the transmission power value that fulfills the first condition, and the relay station relays the relay wave with the relay power value that fulfills the second condition.
16. 16 . The control apparatus according to claim 9 , wherein the first condition is that the transmission wave coming from the first communication station, when the signal-to-interference noise power ratio (SINR) given upon the relay station's relay-transmitting the transmission wave being transmitted by the first communication station and upon the second communication station's receiving the relay-transmitted transmission wave satisfies the second reference value, is transmitted within the range of the allowable transmission power in the first communication station, and the second condition is that the relay power value to relay-transmit the relay wave, when the signal-to-interference noise power ratio (SINR) given upon the second communication station's receiving the relay power value of the relay wave being relay-transmitted by the relay station satisfies the second reference value, is within the range of the allowable transmission power in the relay station.
17. 17 . A relay station comprising: one or more antennas; wireless equipment to be connected to the one or more antennas; and a control circuit, the relay station: non-regenerative-relaying communications between a first communication station and a second communication station in accordance with control apparatus; and relay-transmitting a relay wave with a relay power value of such a limit as to fulfill a second condition when a transmission wave being transmitted from the first communication station and being relay-transmitted by the relay station fulfills a first condition about a signal-to-interference noise power ratio (SINR) and when the relay wave being relay-transmitted by the relay station and reaching the second communication station fulfills the second condition about the signal-to-interference noise power ratio (SINR) and the relay power value in the relay station.
18. 18 . The relay station according to claim 17 , wherein the first condition is that the signal-to-interference noise power ratio (SINR), given when the transmission wave transmitted by the first communication station is relay-transmitted by the relay station, satisfies a first reference value, and the second condition is that the relay power value to relay-transmit the relay wave, in a case where the signal-to-interference noise power ratio (SINR) given when the relay wave being relay-transmitted by the relay station is received by the second communication station satisfies a second reference value, is within a range of allowable transmission power in the relay station.
19. 19 . The relay station according to claim 18 , wherein the control apparatus, when the relay wave fulfills the second condition, notifies the relay station of the relay power value of the relay wave fulfilling the second condition and information for specifying the first reference value, and the relay station relay-transmits the relay wave with the notified relay power value when the signal-to-interference noise power ratio (SINR) given upon relay-transmitting the transmission wave by the relay station satisfies the first reference value.
20. 20 . A communication method of communications among a first communication station, a second communication station, and a relay station to non-regenerative-relay the communications between the first communication station and the second communication station, the method comprising: causing the relay station to relay-transmit a relay wave with a relay power value of such a limit as to fulfill a second condition when a transmission wave being transmitted from the first communication station and being relay-transmitted by the relay station fulfills a first condition about a signal-to-interference noise power ratio (SINR) and when the relay wave being relayed by the relay station and reaching the second communication station fulfills the second condition about the signal-to-interference noise power ratio (SINR) and the relay power value in the relay station.

Description

CROSS REFERENCE TO THE RELATED APPLICATION This application claims the benefit of Japanese Patent Application No. 2022-176686, filed on Nov. 2, 2022, which is hereby incorporated by reference herein in its entirety. BACKGROUND Technical Field The present disclosure pertains to a communication system, a control apparatus, a relay station, and a communication method. Description of the Related Art Super low delay communications equal to or shorter than sub-milliseconds are expected in wireless communications exemplified by 5th Generation Mobile Communication System (5G) and equivalences. On the other hand, expansions of cell coverage areas are desired in terms of improving communication services, and relay communications via relay stations are effective in attaining the expansions. By the way, non-regenerative relay configured not to demodulate and decode at the relay station is desirable as a relay technology exhibiting a small quantity of delay. PRIOR ART DOCUMENTS Non-Patent Documents [Non-Patent Document 1] 3GPP (registered trademark) TS 38.174 V17.0.0(2022-03)[Non-Patent Document 2] 3GPP (registered trademark) TS 38.106 V17.0.0(2022-03) SUMMARY However, a relay device amplifies not only a relayed signal but also unnecessary signals of noises and interferences inclusive when performing non-regenerative relay. Therefore, e.g., the non-regenerative-relay on an uplink has a possibility of deteriorating a signal-to-interference noise power ratio (SINR) of a reception signal for other terminals excluding a relay target terminal when a base station as a reception station receives the signal. Note that the non-regenerative-relay on a downlink also has the possibility of deteriorating the SINR of the non-regenerative-relayed signal among plural terminals. An aspect of an embodiment of the disclosure resides in performing the non-regenerative-relay in a way that suppresses the deterioration of the SINR of the reception signal. One aspect of the embodiment of the disclosure is exemplified by a communication system. The communication system includes a first communication station, a second communication station, a relay station to non-regenerative-relay communications between the first communication station and the second communication station, and a control apparatus. The relay station relay-transmits a relay wave with a relay power value of such a limit as to fulfill a second condition when a transmission wave being transmitted from the first communication station and being relay-transmitted by the relay station fulfills a first condition about a signal-to-interference noise power ratio (SINR) and when the relay wave being relay-transmitted by the relay station and reaching the second communication station fulfills the second condition about the signal-to-interference noise power ratio (SINR) and the relay power value in the relay station. The communication system is enabled to perform the non-regenerative-relay in a way that suppresses the deterioration of the SINR of the reception signal. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a communication system according to a first embodiment; FIG. 2 is a diagram illustrating another communication system embraced by the first embodiment; FIG. 3 is a diagram illustrating a hardware configuration of a control apparatus; FIG. 4 is a diagram illustrating power of reception signals at a second communication station (reception station), the reception signals being transmitted from respective transmission stations in communications by the communication system; FIG. 5 is a diagram illustrating a profile of reception signal power at a base station operating as a second communication station (reception station) when the communication system controls relay power in a relay station; FIG. 6 is a flowchart illustrating a processing flow in the communication system according to the first embodiment; FIG. 7 is a flowchart illustrating the processing flow in the communication system according to the first embodiment; FIG. 8 is a flowchart illustrating a processing flow in the communication system according to a second embodiment; FIG. 9 is a flowchart illustrating the processing flow in the communication system according to the second embodiment; FIG. 10 is a diagram illustrating a profile of the reception signal power in the base station as a second communication station (reception station) when the communication system according to a third embodiment controls transmission signal power in the relay station; FIG. 11 is a flowchart illustrating a processing flow according to the third embodiment; FIG. 12 is a flowchart illustrating the processing flow according to the third embodiment; and FIG. 13 is a flowchart illustrating a processing flow of the relay station according to a fourth embodiment. DESCRIPTION OF THE EMBODIMENTS A communication system 100, a control apparatus 1, a relay station 3, and a communication method will hereinafter be described with referenc