Communication system, communication method, and computer program

Abstract

To provide a communication system, a communication method, and a computer program that switch a transmission line to allow transmission and reception of radio signals through another transmission line.SOLUTION: A communication system according to an embodiment comprises: a parent unit 4 that is connected to a plurality of base station devices 1-3 that are connected to a mobile communication network and transmit and receive radio signals in frequency bands different from each other; a repeater 7 that is connected to the parent unit 4 via a plurality of transmission lines 5-6; and child units 14-16 that transmit radio signals to the repeater 7 via a plurality of transmission lines 8-13 and perform radio communication with a mobile station. The parent unit 4 comprises: a determination unit 471 that determines if a predetermined signal is included in the radio signals transmitted from the plurality of base station devices 1-3 and if there is an abnormality in the transmission quality of a first transmission line to transmit the radio signals; and a switching unit that, when the determination unit 471 determines that the predetermined signal is included in the radio signals and there is an abnormality in the transmission quality of the first transmission line, switches a transmission line to transmit the radio signals from the first transmission line to a second transmission line.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a communication system, a communication method, and a computer program.

Background Art

[0002] A distributed antenna system (DAS) that extends a communication area by distributing radio waves received from a base station through an optical cable is known. A DAS is composed of devices that transmit (transmit and receive) a radio signal sent from a base station to a dead zone where radio waves do not reach directly.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional device, since the external IF for transmitting and receiving radio signals and the transmission path inside the device are fixed, when a failure occurs at a specific location of the device, the transmission and reception through the transmission path are stopped. At this time, if a signal (block) having special information is included in the radio signal, the conventional device cannot use the transmission path.

[0005] Embodiments of the present invention have been made in view of the above circumstances, and provide a communication system, a communication method, and a computer program that enable radio signals to be transmitted and received outside the transmission path by switching the transmission path.

Means for Solving the Problems

[0006] A communication system according to an embodiment includes a master unit connected to a plurality of base station devices that are connected to a mobile communication network and transmit and receive radio signals in different frequency bands, a relay unit connected to the master unit via a plurality of transmission paths, and a slave unit that transmits the radio signal to and from the relay unit via the plurality of transmission paths and performs wireless communication with a mobile station. The master unit includes a determination unit that determines whether a predetermined signal is included in the radio signal transmitted from the plurality of base station devices and whether there is an abnormality in the transmission quality of a first transmission path that transmits the radio signal, and a switching unit that switches the transmission path that transmits the radio signal from the first transmission path to a second transmission path when the determination unit determines that the predetermined signal is included in the radio signal and there is an abnormality in the transmission quality of the first transmission path.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0008] Hereinafter, a communication system, a communication method, and a computer program according to an embodiment will be described with reference to the drawings. In the following embodiments, the same reference numerals are used for parts that perform the same operations, and redundant descriptions will be omitted.

[0009] FIG. 1 is a block diagram showing a configuration example of a communication system including a master unit according to an embodiment. An example of the configuration of the communication system including the master unit according to the present embodiment will be described with reference to FIG. 1.

[0010] The communication system includes, for example, a base station device 1 (Base Station A), a base station device 2 (Base Station B), a base station device 3 (Base Station C), a master unit 4, transmission lines 5-6, a relay unit 7, transmission lines 8-13, and slave units 14-16.

[0011] The base station devices 1-3 each have a plurality of antennas, and the master unit 4 performs wireless communication with the base station devices 1-3 via external IFs (for example, antenna TRXs 1-TRX4) for connecting to the base station devices 1-3. For example, the antennas of the base station devices 1-3 and the master unit 4 are 4×4 MIMO, and four systems of wireless signals (for example, Stream0, Stream1, Stream2, Stream3) are transmitted for each of the base station devices 1-3.

[0012] The master unit 4 and the relay unit 7 are connected via an optical fiber 5-6, and the wireless signals Stream0-3 are transmitted. Also, the relay unit 7 and the slave unit 14 are connected via an optical fiber 8-9, and the wireless signals Stream0-3 are transmitted.

[0013] Also, the relay unit 7 and the slave unit 15 are connected via an optical fiber 10-11, and the wireless signals Stream0-3 are transmitted. Also, the relay unit 7 and the slave unit 16 are connected via an optical fiber 12-13, and the wireless signals Stream0-3 are transmitted.

[0014] The slave units 14-16 each have antennas ANT1-4, are connected to a mobile station, and transmit and receive to the mobile station wireless signals corresponding to the base station device of the communication carrier to which the user of the mobile station subscribes. Note that, for the sake of explanation, three base station devices and three slave units are assumed, but this is not limiting, and there may be less than three base station devices and less than three slave units, or there may be three or more base station devices and less than three slave units.

[0015] Also, in this embodiment, the transmission lines include optical fibers 5-6, 8-13, but this is not limiting, and three or more optical fibers may be connected between devices as the transmission lines.

[0016] Next, the master device 4 will be described in detail. FIG. 2 is a block diagram showing a configuration example of the master device, the transmission path, and the relay device according to an embodiment.

[0017] The master device 4 includes a first stream block 41, a second stream block 42, a third stream block 43, a fourth stream block 44, switches 45-46, a processor 47, a fifth stream block 48, and a sixth stream block 49. The master device 4 includes, for example, at least one processor and a memory in which a program executed by the processor is recorded, and is configured to be able to realize various functions by software or a combination of software and hardware.

[0018] The first stream block 41 aggregates the radio signals Stream0 transmitted from each of the base station devices 1-3 and generates Streams0. The second stream block 42 aggregates the radio signals Stream1 transmitted from each of the base station devices 1-3 and generates Streams1. The third stream block aggregates the radio signals Stream2 transmitted from each of the base station devices 1-3 and generates Streams2. The fourth stream block aggregates the radio signals Stream3 transmitted from each of the base station devices 1-3 and generates Streams3.

[0019] The switch 45 is communicably connected to the first stream block 41, the processor 47, the fifth stream block 48, and the sixth stream block 49. Based on a switching signal from the processor 47 described later, the switch 45 switches the transmission destination of the radio signal Streams0 transmitted from the first stream block 41 to the fifth stream block 48 (StreamsA) or the sixth stream block (StreamsB).

[0020] That is, the switch 45 switches the transmission path for transmitting the wireless signal Streams0 to the optical fiber 5 or the optical fiber 6 based on the switching signal from the processor 47. In the present embodiment, hereinafter, the optical fiber 5 is taken as the first transmission path, and the optical fiber 6 is taken as the second transmission path.

[0021] The switch 46 is communicably connected to the second stream block 42, the processor 47, the fifth stream block 48, and the sixth stream block 49. The switch 46 switches the destination of the wireless signal Streams1 transmitted from the second stream block 42 to the fifth stream block 48 or the sixth stream block based on the switching signal from the processor 47 described later. That is, the switch 46 switches the transmission path for transmitting the wireless signal Streams1 to the first transmission path or the second transmission path based on the switching signal from the processor 47.

[0022] Also, a switch (not shown) may be connected to the third stream block 43 and the fourth stream block 44 respectively. Similar to the switches 45-46, the switch switches the transmission path for transmitting the wireless signal Streams2 to the first transmission path or the second transmission path based on the signal from the processor 47, and switches the transmission path for transmitting the wireless signal Streams3 to the first transmission path or the second transmission path based on the signal from the processor 47.

[0023] The processor 47 is typically a CPU (Central Processing Unit) and / or a GPU (Graphics Processing Unit), but may also be a microcontroller, an FPGA (Field Programmable Gate Array), or a DSP (Digital Signal Processor), etc.

[0024] The processor 47 can implement various functions of the master unit 4 by executing programs such as system software, application software, or firmware stored in the memory. The processor 47 includes a determination unit 471 and a switching unit 472.

[0025] The determination unit 471 determines whether a predetermined signal is included in the radio signals Streams0 - Streams3 transmitted (transmitted) from the base station apparatuses 1 - 3. The predetermined signal is, for example, a synchronization signal block (SSB: SS / PBCH Block). The synchronization signal block has a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). The determination unit 471 transmits the determination result regarding the signal to the switching unit 472.

[0026] Also, the determination unit 471 determines whether there is an abnormality in the transmission quality of the transmission paths that transmit the radio signals Streams0 - Streams3. For example, the determination unit 471 determines whether there is an abnormality in the transmission quality of the first transmission path that transmits the radio signal Streams0 and the radio signal Streams1.

[0027] Also, for example, the determination unit 471 determines whether there is an abnormality in the transmission quality of the second transmission path that transmits the radio signal Streams2 and the radio signal Streams3. Note that the evaluation scale for normal / abnormal transmission quality by the determination unit 471 is performed by a generally known method. The determination unit 471 transmits the determination result regarding the transmission quality to the switching unit 472.

[0028] Also, the determination unit 471 demodulates the radio signals Streams0 - Streams3 using the demodulation function of the master unit 4, and analyzes the importance of the radio signals Streams0 - Streams3 based on the information extracted by demodulating the radio signals Streams0 - Streams3.

[0029] For example, as shown in FIG. 2, when the radio signal Streams0 and the radio signal Streams1 are transmitted to the fifth stream block 48, and the radio signal Streams2 and the radio signal Streams3 are transmitted to the sixth stream block, the determination unit 471 compares the radio signal Streams0 / 1 and the radio signal Streams2 / 3 using the information that can be obtained by demodulating the radio signal Streams0 / 1 and the radio signal Streams2 / 3, and determines (decides) the radio signal with a high importance level (or the radio signal with a low importance level). The determination unit 471 transmits the determination result regarding the importance level to the switching unit 472.

[0030] The switching unit 472 receives the determination result regarding the signal transmitted from the determination unit 471, the determination result regarding the transmission quality, and the determination result regarding the importance level. The switching unit 472 generates a switching signal for switching the transmission path for transmitting the corresponding radio signal according to the received determination result, and transmits the switching signal to the corresponding switch.

[0031] For example, when the switching unit 472 receives the determination result that a predetermined signal is included in the radio signal Streams0 and the determination result that there is an abnormality in the transmission quality of the first transmission path for transmitting the radio signal Streams0, the switching unit 472 transmits a switching signal to the switch 45 to switch the transmission destination of the radio signal Streams0 from the fifth stream block 48 to the sixth stream block 49, that is, to switch the transmission path for transmitting the radio signal Streams0 from the first transmission path to the second transmission path. The switch 45 switches the transmission destination of the radio signal Streams0 from the fifth stream block 48 to the sixth stream block 49 based on the received switching signal.

[0032] Also, for example, when the switching unit 472 receives a determination result that a predetermined signal is included in the wireless signal Streams1 and a determination result that there is an abnormality in the transmission quality of the first transmission path that transmits the wireless signal Streams1, the switching unit 472 causes the transmission destination of the wireless signal Streams1 to be switched from the fifth stream block 48 to the sixth stream block 49, that is, transmits a switching signal to the switch 46 to cause the transmission path that transmits the wireless signal Streams1 to be switched from the first transmission path to the second transmission path. The switch 46 switches the transmission destination of the wireless signal Streams0 from the fifth stream block 48 to the sixth stream block 49 based on the received switching signal.

[0033] Also, when the switching unit 472 receives a determination result that a predetermined signal is included in the wireless signal Streams0, a determination result that there is an abnormality in the transmission quality of the first transmission path that transmits the wireless signal Streams0, and a determination result that the importance of the wireless signal Streams0 is higher than the importance of other wireless signals, the switching unit 472 may transmit a switching signal to the switch 45 to cause the transmission destination of the wireless signal Streams0 to be switched from the fifth stream block 48 to the sixth stream block 49, that is, to cause the transmission path that transmits the wireless signal Streams0 to be switched from the first transmission path to the second transmission path. The switch 45 switches the transmission destination of the wireless signal Streams0 from the fifth stream block 48 to the sixth stream block 49 based on the received switching signal.

[0034] Further, when the switching unit 472 receives a determination result that a predetermined signal is included in the wireless signal Streams1 and a determination result that there is an abnormality in the transmission quality of the first transmission path that transmits the wireless signal Streams1, and also receives a determination result that the importance of the wireless signal Streams1 is higher than the importance of other wireless signals, the switching unit 472 may transmit a switching signal to the switch 46 to cause the transmission destination of the wireless signal Streams1 to be switched from the fifth stream block 48 to the sixth stream block 49, that is, to cause the transmission path that transmits the wireless signal Streams1 to be switched from the first transmission path to the second transmission path. The switch 46 switches the transmission destination of the wireless signal Streams1 from the fifth stream block 48 to the sixth stream block 49 based on the received switching signal. Note that, similarly to the above, for the wireless signal Streams2 and the wireless signal Streams3, a process of switching from the second transmission path to the first transmission path may be performed.

[0035] The memory includes, for example, a main memory and an auxiliary memory. The main memory may include, for example, a ROM (read-only memory) and a RAM (random-access memory). The ROM is a non-volatile memory exclusively used for reading data, and can store data and various setting values used when the processor 47 performs various processes. Further, the RAM can be used as a so-called work area for temporarily storing data when the processor 47 performs various processes. The main memory of the present embodiment is, for example, a RAM and is used as a temporary storage memory.

[0036] The auxiliary memory is a non-transitory computer-readable memory medium of a computer centered around the processor 47. The auxiliary memory is, for example, an EEPROM (registered trademark) (electric erasable programmable read-only memory), an HDD (hard disk drive), or an SSD (solid state drive). The auxiliary memory can store data used by the processor 47 to perform various processes, data generated by the processes in the processor 47, or various setting values.

[0037] Next, an example of the operations of the determination unit 471 and the switching unit 472 of the master device 4 will be described with reference to the drawings. FIG. 3 is a flowchart for explaining an example of the operations of the determination unit and the switching unit of the master device according to an embodiment. FIG. 4 is a flowchart for explaining another example of the operations of the determination unit and the switching unit of the master device according to an embodiment.

[0038] The process of FIG. 3 starts at an arbitrary timing. For example, when the determination unit 471 determines that a predetermined signal is included in the radio signals Streams0 - Streams3 transmitted from a plurality of base station devices, it determines whether there is an abnormality in the transmission quality of the transmission path that transmits the radio signals Streams0 - Streams3 (step S1).

[0039] When the determination unit 471 determines that there is an abnormality in the transmission quality of the transmission path that transmits at least one of the radio signals Streams0 - Streams3 (step S1, YES), it transitions to the process of step S2. Also, when the determination unit 471 determines that there is no abnormality in the transmission quality of the transmission path that transmits the radio signals Stream0 - Streams3 (step S1, NO), it ends the process.

[0040] Next, the case where the determination unit 471 determines that there is an abnormality in the first transmission path that transmits the wireless signal Streams0 or the wireless signal Streams1 will be described with reference to FIG. 3. For the sake of explanation, it is assumed that the wireless signals Streams0 - Streams1 (Streams0 / 1) are transmitted through the first transmission path, and the wireless signals Streams2 - Streams3 (Streams2 / 3) are transmitted through the second transmission path. As shown in FIG. 3, when the determination unit 471 determines that there is an abnormality in the transmission quality of the first transmission path that transmits the wireless signal Streams0 or Streams1 (step S1, YES), it transitions to the process of step S2. Also, when the determination unit 471 determines that there is no abnormality in the transmission quality of the first transmission path that transmits the wireless signal Streams0 or Streams1 (step S1, NO), the process ends.

[0041] Next, the determination unit 471 demodulates the wireless signals Streams0 / 1 and the wireless signals Streams2 / 3 using the demodulation function. The determination unit 471 compares the wireless signals Streams0 / 1 and the wireless signals Streams2 / 3 and determines the importance level based on the information extracted by demodulating the wireless signals Streams0 / 1 and the information extracted by demodulating the wireless signals Streams2 / 3 (step S2).

[0042] As shown in FIG. 3, when the determination unit 471 determines that the wireless signal Streams0 / 1 has a higher importance level than the wireless signal Streams2 / 3 (Streams0 / 1 > Streams2 / 3), it transitions to the process of step S3. When the determination unit 471 determines that the wireless signal Streams2 / 3 has a higher importance level than the wireless signal Streams0 / 1 or the importance levels of the wireless signal Streams2 / 3 and the wireless signal Streams0 / 1 are equal (Streams2 / 3 ≧ Streams0 / 1), the process ends.

[0043] As shown in FIG. 3, when the determination unit 471 determines that the importance of the radio signal 0 / 1 is higher than that of the radio signals Streams2 / 3, the switching unit 472 uses the switch 45 to switch the transmission destination of the radio signal 0 / 1 from StreamsA to StreamsB (step S3), and ends the process. The procedure for switching the transmission destination of the radio signal Streams2 / 3 from StreamsB to StreamsA is the same. The case where the determination unit 471 determines that there is an abnormality in the second transmission path for transmitting the radio signal Streams2 or the radio signal Streams3 will be described with reference to FIG. 4.

[0044] As shown in FIG. 4, when the determination unit 471 determines that there is an abnormality in the transmission quality of the second transmission path for transmitting the radio signal Streams2 or Streams3 (step S1, YES), it transitions to the process of step S2. Also, when the determination unit 471 determines that there is no abnormality in the transmission quality of the second transmission path for transmitting the radio signal Streams2 or Streams3 (step S1, NO), the process ends. When the determination unit 471 determines that there is an abnormality in the second transmission path for transmitting the radio signal Streams2 or the radio signal Streams3, if the determination unit 471 determines that the radio signal Streams2 / 3 has a higher importance than the radio signal Streams0 / 1 (Streams2 / 3>Streams0 / 1), it transitions to the process of step S3. If the determination unit 471 determines that the radio signal Streams0 / 1 has a higher importance than the radio signal Streams2 / 3 or the importance of the radio signal Streams0 / 1 is equal to that of the radio signal Streams2 / 3 (Streams0 / 1≧Streams2 / 3), the process ends. When the determination unit 471 determines that the importance of the radio signal 2 / 3 is higher than that of the radio signal Streams0 / 1, the switching unit 472 uses the switch 45 to switch the transmission destination of the radio signal 2 / 3 from StreamsB to StreamsA (step S3), and ends the process.

[0045] According to the communication system according to this embodiment, when an abnormality occurs in the transmission quality of a transmission path that is the destination of a radio signal when a specific failure occurs, by switching the transmission path in which the abnormality has occurred, it is possible to shorten the time during which radio signals cannot be transmitted and received, rather than a simple degradation operation.

[0046] Also, according to the communication system according to this embodiment, by using the demodulation function of the master unit to determine the importance of radio signals, when an abnormality occurs in the transmission quality of a transmission path, it is possible to switch the transmission paths other than the corresponding transmission path according to the importance and preferentially transmit and receive radio signals with a high importance.

[0047] That is, according to the communication system, communication method, and computer program of this embodiment, by switching the transmission path, it becomes possible to transmit and receive radio signals outside the said transmission path.

[0048] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0049] 1-3…Base station device 4…Master unit 41-44…Stream block 45-46…Switch 47…Processor 471…Determination unit 472…Switching unit 48-49…Stream block 5-6…Optical fiber 7…Relay 8-13…Optical fiber 14-16…Slave unit

Claims

1. A master unit connected to a plurality of base station devices connected to a mobile communication network and transmitting and receiving radio signals in different frequency bands, a relay unit connected to the master unit via a plurality of transmission lines, and the relay unit And a slave unit that transmits the radio signal via a plurality of the transmission lines and performs wireless communication with a mobile station, the communication system comprising: The master unit: A determination unit that determines whether a predetermined signal is included in the radio signals transmitted from the plurality of base station devices and whether there is an abnormality in the transmission quality of a first transmission line that transmits the radio signals; A switching unit that causes the transmission line that transmits the radio signal to be switched from the first transmission line to a second transmission line when the determination unit determines that a predetermined signal is included in the radio signal and there is an abnormality in the transmission quality of the first transmission line; A communication system comprising:

2. The communication system according to claim 1, wherein the determination unit analyzes the importance of the radio signal based on information extracted by demodulating the radio signals transmitted from the plurality of base station devices.

3. The switching unit is configured such that the determination unit determines that a predetermined signal is included in a first radio signal and a second radio signal transmitted from the plurality of base station devices, and that there is an abnormality in the transmission quality of the first transmission line that transmits the first radio signal. When it is determined that the importance of the first radio signal is higher than that of the second radio signal, the transmission line that transmits the first radio signal is switched from the first transmission line to the second transmission line. The communication system according to claim 2.

4. A communication method executed in a communication system including a master unit connected to a plurality of base station devices connected to a mobile communication network and transmitting and receiving radio signals in different frequency bands, a relay unit connected to the master unit via a plurality of transmission lines, and the relay unit And a slave unit that transmits the radio signal via a plurality of the transmission lines and performs wireless communication with a mobile station, the method comprising: Determining whether a predetermined signal is included in the radio signals transmitted from the plurality of base station devices and whether there is an abnormality in the transmission quality of a first transmission line that transmits the radio signals; A communication method for causing a transmission path for transmitting the wireless signal to be switched from a first transmission path to a second transmission path when it is determined that a predetermined signal is included in the wireless signal and there is an abnormality in the transmission quality of the first transmission path.

5. The communication method according to claim 4, wherein the importance of the wireless signal is analyzed based on information extracted by demodulating the wireless signals transmitted from a plurality of the base station devices.

6. When it is determined that a predetermined signal is included in a first wireless signal and a second wireless signal transmitted from a plurality of the base station devices, and there is an abnormality in the transmission quality of the first transmission path for transmitting the first wireless signal, and it is determined that the first wireless signal has a higher importance than the second wireless signal, causing the transmission path for transmitting the first wireless signal to be switched from the first transmission path to the second transmission path, the communication method according to claim 5.

7. A computer program for causing a computer to execute the communication method according to any one of claims 4 to 6.

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