WO2022244152A1

WO2022244152A1 - Communication system, communication method, and base station communication device

Info

Publication number: WO2022244152A1
Application number: PCT/JP2021/019022
Authority: WO
Inventors: 満西野; 大樹柴山; 史洋山下
Original assignee: 日本電信電話株式会社
Priority date: 2021-05-19
Filing date: 2021-05-19
Publication date: 2022-11-24
Also published as: JPWO2022244152A1

Abstract

According to this communication system, communications are performed between base stations and terminal stations via a relay station. A first base station transmits a first signal to the relay station. A second base station transmits a second signal having the same information as the first signal to the relay station. The relay station transmits the first signal and the second signal or transmits a combined signal obtained by combining the first signal and the second signal to the terminal stations. The first base station executes delay processing that delays the transmission of the first signal by a first delay time. A reception time difference is the difference between a timing at which the first signal reaches the relay station and a timing at which the second signal reaches the relay station when the delay processing is not executed. On the basis of reception time difference information indicating the reception time difference, the first base station sets the first delay time such that the first signal and the second signal are received in phase with each other by the relay station.

Description

Communication system, communication method, and base station communication device

The present disclosure relates to communication technology for communicating between base stations and terminal stations via relay stations.

Non-Patent Document 1 discloses an infrastructure satellite communication system that is applied to disaster countermeasure services. Communication is performed between a base station and a terminal station via a communication satellite.

Consider a communication system that communicates between base stations and terminal stations via relay stations. A relay station is, for example, a communication satellite. In order to continue communication even when a disaster such as an earthquake occurs or when signal quality deteriorates due to rainfall, it is conceivable to employ a redundant configuration for base stations. In a redundant configuration, multiple base stations are installed in geographically separated locations. For example, base stations are installed at two geographically separated locations.

FIG. 1 is a conceptual diagram for explaining the first comparative example. The communication system includes multiple base stations 1 , relay stations 2 and multiple terminal stations 3 . The plurality of base stations 1 includes a first base station 1-1 and a second base station 1-2. A first base station 1-1 is connected to a network 5 via a first signal processing device 4-1. The second base station 1-2 is connected to the network 5 via the second signal processing device 4-2. Each base station 1 communicates with the terminal station 3 via the relay station 2 , aggregates communications with many terminal stations 3 , and relays them to the network 5 .

The transmission signal that the first base station 1-1 transmits to the relay station 2 is hereinafter referred to as "first signal SG1". Similarly, the transmission signal that the second base station 1-2 transmits to the relay station 2 is hereinafter referred to as "second signal SG2".

In the first comparative example shown in FIG. 1, the first base station 1-1 and the second base station 1-2 use the same frequency channel. However, both the first base station 1-1 and the second base station 1-2 do not communicate at the same time. This is because if both the first base station 1-1 and the second base station 1-2 communicate at the same time, interference will occur between the first signal SG1 and the second signal SG2 of the same frequency channel. While one of the first base station 1-1 and the second base station 1-2 communicates with the terminal station 3 via the relay station 2, the other stands by without communicating.

Consider a case where the quality of the first signal SG1 deteriorates while the first base station 1-1 is communicating with the terminal station 3 via the relay station 2. For example, due to rain or the like, the first signal SG1 is attenuated and the quality of the first signal SG1 is deteriorated. When quality deterioration of the first signal SG1 is detected, the base station 1 communicating with the terminal station 3 is switched from the first base station 1-1 to the second base station 1-2. That is, triggered by the quality deterioration of the first signal SG1, the first base station 1-1 stops communication, and the second base station 1-2 starts communication instead. For example, the second base station 1-2 detects quality deterioration of the first signal SG1, instructs the first base station 1-1 to stop transmitting the first signal SG1, switches the connection to the network 5, and then , start transmitting the second signal SG2. The same applies when the quality of the first signal SG1 is degraded due to a disaster, failure, or the like.

Thus, in the case of the first comparative example shown in FIG. 1, signal quality deterioration triggers the switching of the base station 1 that communicates with the terminal station 3, and the connection to the network 5 is also changed. As a result of such switching processing, communication is temporarily disconnected (interrupted).

FIG. 2 is a conceptual diagram for explaining the second comparative example. In the second comparative example, the first base station 1-1 and the second base station 1-2 use different frequency channels. Since the first signal SG1 and the second signal SG2 do not interfere with each other, both the first base station 1-1 and the second base station 1-2 are always set to the communication state. The terminal station 3 selects either the first base station 1-1 or the second base station 1-2 as a communication partner.

Consider a case where the quality of the first signal SG1 deteriorates while the terminal station 3 selects the first base station 1-1 as the communication partner. When quality deterioration of the first signal SG1 is detected, the terminal station 3 selects the second base station 1-2 as a communication partner. That is, the terminal station 3 switches the communication partner from the first base station 1-1 to the second base station 1-2. As a result, even when the quality of the first signal SG1 is degraded, communication can be continued without interruption.

However, in the case of the second comparative example shown in FIG. 2, the frequency band required for communication is doubled, increasing operating costs. In particular, when the relay station 2 is a communication satellite, the expensive satellite communication usage fee is doubled. In addition, in the transmitting/receiving device of the terminal station 3, two communication circuits are required for the first base station 1-1 and the second base station 1-2. This leads to an increase in equipment cost of the terminal station 3 .

One object of the present disclosure is to enable appropriate continuation of communication when signal quality is degraded, without increasing costs, with respect to communication technology that performs communication between a base station and a terminal station via a relay station. It is to provide technology.

A first aspect relates to a communication system that communicates between a base station and a terminal station via a relay station.
A communication system is
a first base station transmitting a first signal to the relay station;
a second base station that transmits to the relay station a second signal having the same information as the first signal.
The relay station transmits the first signal and the second signal, or a composite signal obtained by combining the first signal and the second signal to the terminal station.
The first base station is configured to perform a delay process to delay transmission of the first signal by a first delay time.
The reception time difference is the difference between the timing at which the first signal reaches the relay station and the timing at which the second signal reaches the relay station when no delay processing is performed.
The first base station sets the first delay time based on the reception time difference information indicating the reception time difference so that the first signal and the second signal are received by the relay station in phase.

A second aspect relates to a communication method for communicating between a base station and a terminal station via a relay station.
Communication method
a process of transmitting a first signal from the first base station to the relay station;
a process of transmitting a second signal having the same information as the first signal from the second base station to the relay station;
A process of transmitting a first signal and a second signal or a combined signal obtained by combining the first signal and the second signal from a relay station to a terminal station;
and delaying the transmission of the first signal at the first base station by a first delay time.
The reception time difference is the difference between the timing at which the first signal reaches the relay station and the timing at which the second signal reaches the relay station when no delay processing is performed.
The delay processing includes processing for setting a first delay time based on reception time difference information indicating the reception time difference so that the first signal and the second signal are received by the relay station in phase.

A third aspect relates to a base station communication apparatus in a communication system in which communication is performed between a base station and a terminal station via a relay station.
A communication system is
a first base station transmitting a first signal to the relay station;
a second base station transmitting a second signal having the same information as the first signal to the relay station;
a relay station that transmits a first signal and a second signal or a composite signal obtained by combining the first signal and the second signal to a terminal station.
The base station communication device of the first base station is configured to execute delay processing for delaying transmission of the first signal by a first delay time.
The reception time difference is the difference between the timing at which the first signal reaches the relay station and the timing at which the second signal reaches the relay station when no delay processing is performed.
The base station communication device of the first base station sets the first delay time based on the reception time difference information indicating the reception time difference so that the first signal and the second signal are received by the relay station in the same phase.

According to the present disclosure, in a communication system in which communication is performed between a base station and a terminal station via a relay station, it is possible to appropriately continue communication when signal quality deteriorates without increasing costs. .

FIG. 5 is a conceptual diagram for explaining a first comparative example; FIG. 11 is a conceptual diagram for explaining a second comparative example; 1 is a conceptual diagram showing a configuration example of a communication system according to an embodiment of the present disclosure; FIG. FIG. 2 is a conceptual diagram for explaining an outline of processing in a communication system according to an embodiment of the present disclosure; FIG. FIG. 2 is a conceptual diagram for explaining an example of a reception time difference in a communication system according to an embodiment of the present disclosure; FIG. FIG. 2 is a conceptual diagram showing another configuration example of a communication system according to an embodiment of the present disclosure; FIG. 4 is a conceptual diagram for explaining delay adjustment processing in the communication system according to the embodiment of the present disclosure; 4 is a flow chart summarizing processing related to delay processing and delay adjustment processing according to the embodiment of the present disclosure; 1 is a block diagram showing an example of a functional configuration of a base station communication device according to an embodiment of the present disclosure; FIG. FIG. 4 is a block diagram showing another example of the functional configuration of the base station communication device according to the embodiment of the present disclosure; 1 is a block diagram showing a configuration example of a base station communication device according to an embodiment of the present disclosure; FIG. FIG. 4 is a conceptual diagram for explaining signal strength adjustment processing according to an embodiment of the present disclosure; FIG. 4 is a conceptual diagram for explaining signal strength adjustment processing according to an embodiment of the present disclosure; 6 is a flowchart showing processing related to signal strength adjustment processing according to the embodiment of the present disclosure;

Embodiments of the present disclosure will be described with reference to the accompanying drawings.

1. Overview FIG. 3 is a conceptual diagram showing a configuration example of a communication system according to this embodiment. The communication system includes multiple base stations 10 , relay stations 20 , and multiple terminal stations 30 . The base station 10 and terminal station 30 communicate with each other via the relay station 20 . The relay station 20 is, for example, a communication satellite. The terminal station 30 may include a personal computer, an IP telephone terminal, a smart phone, and the like.

A redundant configuration is adopted for the base station 10 in order to continue communication even when a disaster such as an earthquake occurs or when signal quality deteriorates due to rainfall. The plurality of base stations 10 includes a first base station 10-1 and a second base station 10-2. The first base station 10-1 and the second base station 10-2 are installed in geographically separated locations.

The first signal processing device 40-1 on the side of the first base station 10-1 is connected to the network 50. Also, the first signal processing device 40-1 on the first base station 10-1 side and the second signal processing device 40-2 on the second base station 10-2 side are connected so as to be able to communicate with each other. The first base station 10-1 is connected to the network 50 via the first signal processing device 40-1. The second base station 10-2 is connected to the network 50 via the second signal processing device 40-2 and the first signal processing device 40-1. Each base station 10 communicates with the terminal station 30 via the relay station 20 , aggregates communications with many terminal stations 30 , and relays them to the network 50 .

FIG. 4 is a conceptual diagram for explaining the outline of processing in the communication system according to the present embodiment. The first signal SG1 is a transmission signal that the first base station 10-1 transmits to the relay station 20. FIG. The second signal SG2 is a transmission signal that the second base station 10-2 transmits to the relay station 20. FIG. The first signal SG1 and the second signal SG2 have the same information. The first base station 10-1 receives the first signal SG1 from the first signal processing device 40-1 and transmits the first signal SG1 to the terminal station 30 via the relay station 20. FIG. The second base station 10-2 receives the first signal SG1 as the second signal SG2 from the first signal processing device 40-1 via the second signal processing device 40-2 (SG2=SG1). The second base station 10-2 then transmits a second signal SG2 having the same information as the first signal SG1 to the terminal station 30 via the relay station 20. FIG.

The first base station 1-1 and the second base station 1-2 use the same frequency channel. Also, both the first base station 1-1 and the second base station 1-2 are always set to the communication state. Therefore, it is necessary to avoid interference between the first signal SG1 and the second signal SG2 in the relay station 20 and the like. For that purpose, the relay station 20 should be able to receive the first signal SG1 and the second signal SG2 having the same information in the same phase. In other words, the first signal SG1 and the second signal SG2 having the same information should reach the relay station 20 in the same phase. In that case, the relay station 20 or the terminal station 30 can combine the first signal SG1 and the second signal SG2 without causing interference.

According to the present embodiment, either first base station 10-1 or second base station 10-2 can receive first signal SG1 and second signal SG2 in phase so that relay station 20 can receive first signal SG1 and second signal SG2 One of them performs "delay processing" to delay signal transmission. A case where the first base station 10-1 performs delay processing will be described below. The same applies when the second base station 10-2 performs delay processing.

In the delay process, the first base station 10-1 delays transmission of the first signal SG1 by "first delay time D1". The first base station 10-1 sets the first delay time D1 so that the first signal SG1 and the second signal SG2 are received by the relay station 20 in phase. A specific method for setting and adjusting the first delay time D1 will be described in detail later.

The relay station 20 receives the first signal SG1 and the second signal SG2 in phase. The relay station 20 transmits (transfers) the received first signal SG1 and second signal SG2 to the terminal station 30 . The terminal station 30 combines and receives the in-phase first signal SG1 and second signal SG2 having the same information. Alternatively, the relay station 20 combines the received first signal SG1 and second signal SG2 to generate a combined signal SGC. The relay station 20 then transmits to the terminal station 30 a combined signal SGC obtained by combining the first signal SG1 and the second signal SG2. Terminal station 30 receives combined signal SGC.

The quality of the first signal SG1 transmitted from the first base station 10-1 may deteriorate. For example, rain or the like may attenuate the first signal SG1 and degrade the quality of the first signal SG1. As another example, the quality of the first signal SG1 may be degraded due to a disaster, failure, or the like. According to the present embodiment, even if the quality of the first signal SG1 deteriorates, it is possible to appropriately continue communication by the second signal SG2 having the same information as the first signal SG1. Since the base station is not switched as in the first comparative example shown in FIG. 1, no communication disconnection occurs.

The same applies when the quality of the second signal SG2 transmitted from the second base station 10-2 deteriorates. Even if the quality of the second signal SG2 deteriorates, it is possible to properly continue communication by means of the first signal SG1 having the same information as the second signal SG2. Since the base station is not switched as in the first comparative example shown in FIG. 1, no communication disconnection occurs.

Furthermore, according to the present embodiment, unlike the case of the second comparative example shown in FIG. 2, separate frequency channels are used for the first base station 1-1 and the second base station 1-2. No need. Therefore, no increase in operating costs occurs. Further, in the transmitting/receiving device of the terminal station 30, two communication circuits for the first base station 10-1 and the second base station 10-2 are unnecessary. Therefore, the device cost of the terminal station 30 does not increase.

As described above, according to the present embodiment, in a communication system in which communication is performed between the base station 10 and the terminal station 30 via the relay station 20, the signal quality can be improved without increasing the cost. It is possible to appropriately continue communication when deterioration occurs.

2. Delay Processing and Delay Adjustment Processing Delay processing and delay adjustment processing according to the present embodiment will be described in detail below.

2-1. Reception Time Difference Information It is assumed that delay processing is not executed in the first base station 1-1. In that case, the first signal SG1 and the second signal SG2 having the same information arrive at the relay station 20 at different timings. The difference between the timing at which the first signal SG1 reaches the relay station 20 and the timing at which the second signal SG2 reaches the relay station 20 when the delay processing is not executed is hereinafter referred to as "reception time difference ΔD".

FIG. 5 is a conceptual diagram for explaining an example of the reception time difference ΔD. The first communication delay α is the round trip time of the signal between the first base station 10-1 and the relay station 20. FIG. The second communication delay β is the signal transmission time on the communication route from the second base station 10-2 to the first base station 10-1 via the relay station 20. FIG. The third communication delay γ is the signal transmission time between the first base station 10-1 (first signal processing device 40-1) and the second base station 10-2 (second signal processing device 40-2). , which is the signal transmission time that does not pass through the relay station 20 . In this case, the reception time difference ΔD is represented by "β+γ-α".

The communication delays α, β, γ are measured or estimated in advance. The reception time difference ΔD is calculated in advance based on the communication delays α, β and γ. Information indicating the reception time difference ΔD is provided in advance to the first base station 10-1.

Alternatively, the first base station 10-1 itself may measure the first communication delay α and the second communication delay β at the start of communication. For example, the first base station 10 - 1 transmits the first delay measurement signal to the relay station 20 . The relay station 20 receives the first delay measurement signal and sends the first delay measurement signal back to the first base station 10-1. The first base station 10-1 measures the first communication delay α based on the transmission timing and reception timing of the first delay measurement signal. Subsequently, the first base station 10-1 stops signal transmission processing, and instead the second base station 10-2 transmits the second delay measurement signal to the first base station 10-1 via the relay station 20. Send. The first base station 10-1 receives the second delay measurement signal transmitted from the second base station 10-2. The second delay measurement signal contains timing information transmitted from the second base station 10-2. The first base station 10-1 measures the second communication delay β based on the transmission timing and reception timing of the second delay measurement signal. Information on the third communication delay γ is given in advance. The first base station 10-1 calculates the reception time difference ΔD based on the communication delays α, β, γ.

FIG. 6 shows another configuration example of the communication system according to this embodiment. In the example shown in FIG. 6, one signal processing device 40 is installed at an intermediate point between the first base station 10-1 and the second base station 10-2. Both the first base station 10-1 and the second base station 10-2 are connected to the network 50 via their signal processors 40. FIG. The first base station 10-1 and the second base station 10-2 receive the first signal SG1 and the second signal SG2 having the same information from the signal processing device 40, respectively. In the example shown in FIG. 6, the third communication delay γ is the signal transmission time between the first base station 10-1 and the signal processing device 40 and the signal transmission time between the second base station 10-2 and the signal processing device 40. is defined as the difference between the signal transmission time of Even in this case, the reception time difference ΔD is represented by "β+γ-α". In the case of the configuration shown in FIG. 6, it is possible to minimize the third communication delay γ.

2-2. Initialization of Delay Time As described above, in the delay process, the first base station 10-1 delays the transmission of the first signal SG1 by the "first delay time D1". The first base station 10-1 acquires the information on the reception time difference ΔD, and sets the reception time difference ΔD as the initial value of the first delay time D1. Then, the first base station 10-1 starts delay processing using the initial value of the first delay time D1.

2-3. Delay Adjustment Processing There may be individual differences in the communication circuits of each device. In addition, fluctuations in signal transmission time can cause continuous delay fluctuations. In order to cope with such individual differences and delay variations, the first base station 10-1 may dynamically adjust the first delay time D1 after initializing the first delay time D1. The process of dynamically adjusting the first delay time D1 is hereinafter referred to as "delay adjustment process".

FIG. 7 is a conceptual diagram for explaining delay adjustment processing according to the present embodiment. The relay station 20 receives a first signal SG1 transmitted from the first base station 10-1 and receives a second signal SG2 transmitted from the second base station 10-2. The relay station 20 transmits the received first signal SG1 and second signal SG2 to the first base station 10-1. The first base station 10-1 combines and receives the first signal SG1 and the second signal SG2. Alternatively, the relay station 20 combines the received first signal SG1 and second signal SG2 to generate a combined signal SGC. The relay station 20 then transmits a combined signal SGC obtained by combining the first signal SG1 and the second signal SG2 to the first base station 10-1. The first base station 10-1 receives the combined signal SGC.

The first base station 10-1 demodulates the composite signal SGC obtained by combining the first signal SG1 and the second signal SG2. Then, the first base station 10-1 dynamically adjusts the first delay time D1 based on the demodulation result of the combined signal SGC.

For example, the first base station 10-1 determines whether the demodulation result of the composite signal SGC satisfies a certain quality. More specifically, the first base station 10-1 acquires communication parameters reflecting the demodulation result of the combined signal SGC. For example, the communication parameter is Bit Error Rate (BER). The first base station 10-1 determines whether its communication parameters satisfy certain quality. If the communication parameters do not satisfy the constant quality, the first base station 10-1 changes the first delay time D1 until the communication parameters satisfy the constant quality. A feedback circuit, for example, is used for such adjustment of the first delay time D1.

2-4. Processing Flow FIG. 8 is a flowchart schematically showing processing related to delay processing and delay adjustment processing according to the present embodiment.

In step S100, the first base station 10-1 acquires information indicating the reception time difference ΔD. Information indicating the reception time difference ΔD may be provided in advance to the first base station 10-1. Alternatively, the first base station 10-1 may measure the first communication delay α and the second communication delay β, and calculate the reception time difference ΔD based on the first communication delay α and the second communication delay β.

In step S110, the first base station 10-1 sets the reception time difference ΔD as the initial value of the first delay time D1.

In step S120, the first base station 10-1 performs delay processing and transmission processing. In the delay process, the first base station 10-1 delays the transmission of the first signal SG1 by the first delay time D1. Then, the first base station 10-1 transmits the first signal SG1 to the relay station 20. FIG. The second base station 10-2 transmits to the relay station 20 a second signal SG2 having the same information as the first signal SG1.

In step S130, the relay station 20 transmits the received first signal SG1 and second signal SG2 to the first base station 10-1. The first base station 10-1 combines and receives the first signal SG1 and the second signal SG2. Alternatively, the relay station 20 transmits a combined signal SGC obtained by combining the first signal SG1 and the second signal SG2 to the first base station 10-1. The first base station 10-1 receives the combined signal SGC.

In step S140, the first base station 10-1 determines whether the demodulation result of the combined signal SGC satisfies a certain quality. If the demodulation result of the synthesized signal SGC satisfies a certain level of quality (step S140; Yes), the process returns to step S120. On the other hand, if the demodulation result of the combined signal SGC does not satisfy the certain quality (step S140; No), the process proceeds to step S150.

In step S150, the first base station 10-1 changes the first delay time D1. After that, the process returns to step S120. That is, the first base station 10-1 changes the first delay time D1 until the demodulation result of the combined signal SGC satisfies a certain quality.

By the delay adjustment processing described above, it is possible to dynamically adjust the first delay time D1 according to the situation and further suppress interference between the first signal SG1 and the second signal SG2. As a result, communication quality is improved.

3. Configuration Example A base station 10 according to the present embodiment includes a base station communication apparatus 100 that controls communication of the base station 10 . A configuration example of the base station communication apparatus 100 of the first base station 10-1 will be described below.

FIG. 9 is a block diagram showing an example of the functional configuration of the base station communication device 100. As shown in FIG. Base station communication apparatus 100 includes demodulator 110 , delay controller 120 , and transmitter 130 .

A received signal received by the first base station 10 - 1 from the relay station 20 is input to the demodulation unit 110 . Demodulator 110 demodulates the received signal and outputs received data obtained by demodulation to signal processing device 40 . Demodulator 110 also outputs demodulation result information indicating the demodulation result of the received signal to delay controller 120 . The demodulation result information includes communication parameters reflecting the demodulation result of the received signal. For example, the communication parameter is bit error rate.

The delay control unit 120 holds reception time difference information 200 and delay setting information 300 . The reception time difference information 200 indicates the reception time difference ΔD described above. In the example shown in FIG. 9, the reception time difference information 200 is provided to the base station communication device 100 in advance. The delay setting information 300 indicates the first delay time D1 used in delay processing.

The delay control unit 120 sets the reception time difference ΔD indicated by the reception time difference information 200 as the initial value of the first delay time D1. The delay control unit 120 registers the initial value of the first delay time D1 in the delay setting information 300. FIG. Then, the delay control section 120 notifies the transmission section 130 of the first delay time D1 indicated by the delay setting information 300 .

Also, the delay control unit 120 performs delay adjustment processing. Specifically, delay control section 120 receives demodulation result information from demodulation section 110 and determines whether the demodulation result satisfies a certain level of quality. For example, the delay control unit 120 determines whether the bit error rate satisfies a certain quality. If the demodulation result does not satisfy a certain quality, the delay control section 120 changes the first delay time D1 and updates the delay setting information 300 . Then, the delay control section 120 notifies the transmission section 130 of the first delay time D1 indicated by the delay setting information 300 . The delay control section 120 changes the first delay time D1 until the demodulation result satisfies a certain quality. A feedback circuit, for example, is used for such adjustment of the first delay time D1.

The transmission unit 130 receives transmission data from the signal processing device 40 . The transmitter 130 modulates transmission data to generate a first signal SG1 and transmits the first signal SG1. At this time, the transmission section 130 performs delay processing based on the first delay time D<b>1 notified from the delay control section 120 . Specifically, the transmitter 130 has a delay circuit 135 . Using the delay circuit 135, the transmitter 130 delays the transmission of the first signal SG1 by the first delay time D1.

FIG. 10 is a block diagram showing another example of the functional configuration of the base station communication device 100. As shown in FIG. Explanations that overlap with the example shown in FIG. 9 will be omitted as appropriate. In the example shown in FIG. 10, the base station communication device 100 generates the reception time difference information 200. FIG.

More specifically, demodulation section 110 includes delay measurement section 115 . The delay measurement unit 115 measures the first communication delay α and the second communication delay β. Specifically, when receiving the first delay measurement signal, the delay measurement unit 115 calculates the first communication delay α based on the transmission timing and the reception timing of the first delay measurement signal. Further, when receiving the second delay measurement signal, the delay measurement unit 115 calculates the second communication delay β based on the transmission timing and the reception timing of the second delay measurement signal. The demodulator 110 notifies the delay controller 120 of the first communication delay α and the second communication delay β.

The delay control section 120 receives information on the first communication delay α and the second communication delay β from the demodulation section 110 . Information on the third communication delay γ is given in advance. The delay control unit 120 calculates the reception time difference ΔD based on the communication delays α, β, and γ, and generates reception time difference information 200 . Others are the same as in the case of the example shown in FIG.

FIG. 11 is a block diagram showing a configuration example of base station communication apparatus 100 according to the present embodiment. The base station communication device 100 includes an I/O interface 140, one or more processors 150 (hereinafter simply referred to as "processors 150"), and one or more storage devices 160 (hereinafter simply referred to as "storage devices 160"). ).

The processor 150 performs various information processing. For example, processor 150 includes a CPU (Central Processing Unit).

The storage device 160 stores various information necessary for processing by the processor 150 . For example, the storage device 160 stores the reception time difference information 200 and the delay setting information 300 described above. Examples of the storage device 160 include volatile memory, nonvolatile memory, HDD (Hard Disk Drive), SSD (Solid State Drive), and the like.

The control program 170 is a computer program executed by the processor 150. The functions of the base station communication apparatus 100 (processor 150) are realized by the processor 150 executing the control program 170. FIG. The functional blocks shown in FIGS. 9 and 10 may be implemented by cooperation between the processor 150 executing the control program 170 and the storage device 160. FIG. The control program 170 is stored in the storage device 160 . The control program 170 may be recorded on a computer-readable recording medium. The control program 170 may be provided to the base station communication device 100 via a network.

The base station communication device 100 may be implemented using hardware such as ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), and FPGA (Field Programmable Gate Array).

4. Signal Strength Adjustment Processing As described above, according to the present embodiment, the first signal SG1 is transmitted from the first base station 10-1, the second signal SG2 is transmitted from the second base station 10-2, and the first signal SG2 is transmitted from the second base station 10-2. The signal SG1 and the second signal SG2 are combined in phase. Therefore, even if the signal transmission power per base station 10 is set to half of the conventional one, it is possible to ensure the same communication quality with the same signal-to-noise ratio as the conventional one. From this point of view, the signal transmission power in the first base station 10-1 and the second base station 10-2 may be positively reduced in order to reduce power consumption. For example, the signal transmission power in the first base station 10-1 and the second base station 10-2 is set to half of the conventional one.

However, if the quality of the first signal SG1 or the second signal SG2 is degraded, the signal-to-noise ratio of the composite signal SGC is also degraded. Therefore, when quality deterioration of the first signal SG1 or the second signal SG2 is detected, the "signal strength adjustment process" described below may be performed.

FIG. 12 shows the frame structure of the transmission signal. A frame of transmitted signals includes an identifying header and signaling data. The value of the identification header of the frame of the first signal SG1 is "H1" representing the first base station 10-1. The value of the identification header of the frame of the second signal SG2 is "H2" representing the second base station 10-2.

FIG. 13 shows a frame of a synthesized signal SGC obtained by synthesizing the first signal SG1 and the second signal SG2. When neither the first signal SG1 nor the second signal SG2 is degraded, the value of the identification header of the frame of the combined signal SGC is "H1+H2". When the second signal SG2 is degraded, the value of the identification header of the frame of the synthesized signal SGC becomes "H1". On the other hand, when the first signal SG1 deteriorates, the value of the identification header of the frame of the combined signal SGC becomes "H2". Therefore, quality deterioration of the first signal SG1 or the second signal SG2 can be detected based on the value of the identification header of the frame of the synthesized signal SGC.

FIG. 14 is a flowchart showing processing related to signal strength adjustment processing according to the present embodiment.

In step S200, the relay station 20 or the first base station 10-1 combines and receives the first signal SG1 and the second signal SG2.

In step S210, the relay station 20 or the first base station 10-1 determines whether the quality of the first signal SG1 or the second signal SG2 has deteriorated. More specifically, relay station 20 or first base station 10-1 checks the value of the identification header of the frame of combined signal SGC.

When the value of the identification header is "H1+H2", the relay station 20 or the first base station 10-1 determines that neither the first signal SG1 nor the second signal SG2 has deteriorated. In this case, the process proceeds to step S220. In step S220, the signal strengths of the first signal SG1 and the second signal SG2 are set to default values. For example, the first base station 10-1 (transmitting unit 130) sets the signal transmission power of the first signal SG1 to half of the conventional one, and the second base station 10-2 sets the signal transmission power of the second signal SG2 to Set to half of the conventional setting.

When the value of the identification header is "H1", the relay station 20 or the first base station 10-1 determines that the second signal SG2 has deteriorated. That is, quality deterioration of the second signal SG2 is detected. In this case, the process proceeds to step S230. At step S230, the first base station 10-1 or the relay station 20 increases the signal strength of the first signal SG1. For example, the first base station 10-1 (transmitting unit 130) or the relay station 20 sets the signal strength of the first signal SG1 to double the default value. By increasing the signal strength of the first signal SG1, quality deterioration of the second signal SG2 can be compensated.

On the other hand, if the value of the identification header is "H2", the relay station 20 or the first base station 10-1 determines that the first signal SG1 has deteriorated. That is, quality deterioration of the first signal SG1 is detected. In this case, the process proceeds to step S240. In step S240, the second base station 10-2 or relay station 20 increases the signal strength of the second signal SG2. For example, the second base station 10-2 or the relay station 20 sets the signal strength of the second signal SG2 to double the default value. By increasing the signal strength of the second signal SG2, quality deterioration of the first signal SG1 can be compensated.

The signal strength adjustment processing described above makes it possible to ensure communication quality even when the first signal SG1 or the second signal SG2 is degraded. Also, in normal times when neither the first signal SG1 nor the second signal SG2 is degraded, the signal transmission power in the first base station 10-1 and the second base station 10-2 is actively reduced, and the power consumption as a whole is reduced. can be suppressed.

5. Others According to the present embodiment, the first signal SG1 and the second signal SG2 are synthesized in the same phase. What is synthesized may be a radio frequency band (RF band) signal after modulation, an intermediate frequency band (IF band) signal, or a baseband signal before modulation. good too.

In the present embodiment, the duplex method for transmission and reception is arbitrary. The duplex system may be frequency division duplex (FDD) or time division duplex (TDD).

10... base station, 10-1... first base station, 10-2... second base station, 20... relay station, 30... terminal station, 40... signal processing device, 40-1... first signal processing device, 40 -2... second signal processing device, 50... network, 100... base station communication device, 110... demodulation unit, 115... delay measurement unit, 120... delay control unit, 130... transmission unit, 135... delay circuit, 140... I /O interface, 150... processor, 160... storage device, 170... control program, 200... reception time difference information, 300... delay setting information, SG1... first signal, SG2... second signal, SGC... combined signal

Claims

A communication system for communicating between a base station and a terminal station via a relay station,
a first base station that transmits a first signal to the relay station;
a second base station that transmits a second signal having the same information as the first signal to the relay station;
The relay station transmits to the terminal station the first signal and the second signal, or a combined signal obtained by combining the first signal and the second signal,
The first base station is configured to perform delay processing for delaying transmission of the first signal by a first delay time,
the reception time difference is the difference between the timing at which the first signal reaches the relay station and the timing at which the second signal reaches the relay station when the delay processing is not performed;
The first base station sets the first delay time based on reception time difference information indicating the reception time difference so that the first signal and the second signal are received by the relay station in phase. system.
A communication system according to claim 1,
The first base station sets the reception time difference indicated by the reception time difference information as an initial value of the first delay time, and starts the delay processing using the initial value of the first delay time. Communication system .
A communication system according to claim 1 or 2,
The relay station transmits the first signal and the second signal or the combined signal to the first base station;
The first base station is
demodulating the synthesized signal obtained by synthesizing the first signal and the second signal;
A communication system that dynamically adjusts the first delay time based on a demodulation result of the combined signal.
A communication system according to claim 3,
The first base station is
determining whether the demodulation result of the combined signal satisfies a certain quality;
When the demodulation result of the composite signal does not satisfy the given quality, the first delay time is changed until the demodulation result of the composite signal satisfies the given quality.
A communication system according to any one of claims 1 to 4,
the first communication delay is the round trip time of a signal between the first base station and the relay station;
A second communication delay is a signal transmission time in a communication route from the second base station to the first base station via the relay station,
The communication system, wherein the reception time difference is calculated based on the first communication delay and the second communication delay.
A communication system according to any one of claims 1 to 5,
When quality deterioration of the first signal is detected, the second base station or the relay station increases the signal strength of the second signal,
The communication system, wherein the first base station or the relay station increases the signal strength of the first signal when quality deterioration of the second signal is detected.
A communication method for communicating between a base station and a terminal station via a relay station,
a process of transmitting a first signal from a first base station to the relay station;
a process of transmitting a second signal having the same information as the first signal from a second base station to the relay station;
a process of transmitting the first signal and the second signal or a combined signal obtained by combining the first signal and the second signal from the relay station to the terminal station;
a delay process for delaying transmission of the first signal in the first base station by a first delay time;
the reception time difference is the difference between the timing at which the first signal reaches the relay station and the timing at which the second signal reaches the relay station when the delay processing is not performed;
The delay processing includes processing for setting the first delay time based on reception time difference information indicating the reception time difference so that the first signal and the second signal are received by the relay station in phase. Communication method.
A base station communication device in a communication system that communicates between a base station and a terminal station via a relay station,
The communication system is
a first base station that transmits a first signal to the relay station;
a second base station that transmits a second signal having the same information as the first signal to the relay station;
the relay station transmitting the first signal and the second signal, or a combined signal obtained by combining the first signal and the second signal, to the terminal station;
The base station communication device of the first base station is configured to execute delay processing for delaying transmission of the first signal by a first delay time,
the reception time difference is the difference between the timing at which the first signal reaches the relay station and the timing at which the second signal reaches the relay station when the delay processing is not performed;
Based on reception time difference information indicating the reception time difference, the base station communication device of the first base station controls the first signal so that the first signal and the second signal are received by the relay station in the same phase. A base station communication device that sets the delay time.