JP7764290B2 - Distributed antenna system, master unit, remote unit, and operation control method - Google Patents

Description

Embodiments of the present invention relate to a distributed antenna system, a master unit, a remote unit, and an operation control method.

The communication area of 5G (fifth-generation mobile communication system) is gradually expanding. Optical repeater devices are playing a role in this expansion. Also known as a DAS (Distributed Antenna System), this device comprises a master unit (parent station) connected to a base station and remote units (child stations) connected to the master unit via optical fiber.

Local 5G is a system that allows licensees to provide mobile communications services in areas they own. For example, if a local 5G area is established in an area where a telecommunications carrier's service area is already in operation, there is a risk of radio wave interference if the two frequencies are adjacent. This is because local 5G allows for quasi-synchronous or asynchronous operation using the TDD (Time Division Duplex) method. Therefore, when there is a mixture of carriers using quasi-synchronous and asynchronous operation, the distance between base stations is increased to cause propagation loss and prevent interference.

Japanese Patent Application Laid-Open No. 2001-145155 Japanese Patent Application Laid-Open No. 2001-24546 JP 2016-25382 A

Infrastructure sharing will be applied when 5G is introduced. Infrastructure sharing is the concept of multiple operators jointly using communication infrastructure, primarily for cost benefits. In DAS, too, consideration is being given to accommodating multiple base stations, each owned by a different owner, in a single master unit. If this technology is applied to local 5G, it will be possible for communication operators and licensees to share the same master unit and remote unit. This type of master unit and remote unit is also called operator-shared equipment.

However, when multiple base stations are accommodated in a master unit, radio waves from multiple operators are transmitted and received from the antenna of a single slave station, making it impossible to expect interference prevention effects due to distance. This means that it is difficult to mix operators that operate quasi-synchronously and asynchronously, with different downlink (DL) and uplink (UL) settings (time division multiplexing patterns, TDD patterns) in the air section. These circumstances have been an obstacle to shared use of infrastructure and have also been a factor preventing area expansion. There is a demand for technology that can prevent radio interference, enable the coexistence of operators with different TDD patterns, and accommodate a variety of use cases.

The objective is to provide a distributed antenna system, master unit, remote unit, and operation control method that eliminates constraints related to shared use of infrastructure and increases operational flexibility.

According to an embodiment, a distributed antenna system includes a master unit and a remote unit equipped with an antenna capable of covering a first band and a second band adjacent to the first band. The master unit includes a base station connection unit, a slave station connection unit, a detection unit, and an operation control unit. The base station connection unit is connectable to a first base station assigned the first band and a second base station assigned the second band. The slave station connection unit is connectable to the remote unit. The detection unit detects downlink signals in the first band. The operation control unit allows an operation mode in which the time division multiplexing pattern in the second band differs from the time division multiplexing pattern in the first band during a period in which loss of the downlink signal in the first band is detected from the output of the detection unit.

FIG. 1 is a diagram illustrating an example of a communication system according to an embodiment. FIG. 2 is a diagram illustrating an example of band allocation to a base station. FIG. 3 is a functional block diagram showing an example of the master station 100 and the slave station 200. As shown in FIG. FIG. 4 is a diagram showing an example of a TDD pattern in synchronous operation. FIG. 5 is a diagram for explaining the state of the switch in the DL slot/UL slot. FIG. 6 is a flowchart showing an example of a processing procedure of the master station 100. FIG. 7 is a flowchart showing an example of a processing procedure of the master station 100. FIG. 8 shows an example of a modified TDD pattern. FIG. 9 is a sequence diagram showing an example of a processing procedure when the DL signal is lost. FIG. 10 shows the disappearance of the DL signal in band A. FIG. 11 is a sequence diagram showing an example of a processing procedure when the UL signal is lost. FIG. 12 shows the disappearance of the UL signal in band A. FIG. 13 is a block diagram for explaining switching between synchronous and asynchronous operation between base stations belonging to different master stations.

A communication system according to one embodiment will be described with reference to the drawings. The communication system described below is, for example, a distributed antenna system (DAS), but can also be applied to systems compliant with eCPRI of the ORAN (Open Radio Access Network).

Figure 1 shows an example of a communication system according to one embodiment. The communication system includes a master station (MU) 100 and multiple slave stations 200 (200-1 to 200-n), each connected to the master station 100 via optical fiber. DAS is the name given when focusing on the master station 100 and the slave stations (RUs) 200-1 to 200-n. This is also called an optical repeater system.

The management device (EMS: Element Management System) 300 is connected to the master station 100 via the network NW. Mobile terminals (UE: User Equipment) 3 (3a, 3b, ..., 3m) are connected to one of the slave stations 200-1 to 200-n via a wireless channel.

The base station 100, which serves as a master unit, is connected to base stations BS (BSa, BSb, ..., BSm) via the base station connection unit 101. Each base station BS is connected to the base station connection unit 101 via, for example, a coaxial cable. In other words, the base station connection unit 101 is an interface that inputs and outputs RF (Radio Frequency) signals for each base station (operator). In this embodiment, it is assumed that base station BSa is operated by operator A, base station BSb is operated by operator B, ..., and base station BSm is operated by operator M. In other words, the base station 100 is an example of a shared-operator device.

The master station 100 also functions as a relay device. That is, the master station 100 relays signals exchanged between the mobile terminals 3a, 3b, ..., 3m of each telecommunications carrier and the base stations BSa, BSb, ..., BSm of each telecommunications carrier.

Base stations BSa, BSb, ..., BSm are accommodated in a core device (not shown) of a core network, such as 5G (5th Generation) or LTE (Long-Term Evolution), operated by each of telecommunications carriers A, B, ..., M. The core network controls the radio access network between base stations BSa, BSb, ..., BSm and mobile terminals 3a, 3b, ..., 3m. The core device performs processes such as authentication and security management, session management, policy control, and packet forwarding.

Mobile terminals 3a, 3b, ..., 3m are smartphones, tablets, mobile phones, etc. Mobile terminals 3a, 3b, ..., 3m communicate using communication resources (such as frequency bands) allocated to their respective telecommunications carriers A, B, ..., M. In the following description, mobile terminal 3a may be referred to as the "mobile terminal of telecommunications carrier A" to indicate the telecommunications carrier to which the service is subscribed. Similarly, mobile terminals 3b, ..., 3m may be referred to as the mobile terminals of telecommunications carriers B, ..., M.

The master station 100 collects wireless signals transmitted via UL from mobile terminals 3a, 3b, ..., 3m via slave stations 200-1 to 200-n and transmits them to the base stations BSa, BSa, ..., BSm of the corresponding telecommunications carrier. When connected to slave stations 200-1 to 200-n via optical communication lines, the master station MU is sometimes referred to as an "optical repeater." The master station 100 is equipped with a slave station connection unit 102 that can connect to slave stations 200-1 to 200-n as remote units. The slave station connection unit 102 accommodates optical fibers connected to each of slave stations 200-1 to 200-n and is an interface for inputting and outputting optical signals.

Slave stations 200-1 to 200-n transmit wireless signals via DL from base stations BSa, BSb, ..., BSm via master station MU. Slave stations 200-1 to 200-n can communicate wirelessly with any of mobile terminals 3a, 3b, ..., 3m. In other words, slave stations 200-1 to 200-n can cover the frequency bands allocated to each of telecommunications carriers A, B, ..., M.

The management device 300 functions as a server, controlling each device in the communication system and monitoring its status based on information from the master station 100. The management device 300 provides information about the operational status of the communication system to the client terminals CL-1 to CL-l, and controls the communication system, compiles data, generates display data, and so on, in accordance with requests and instructions from the client terminals CL-1 to CL-l.

Client terminals CL-1 to CL-l are, for example, personal computers. Client terminals CL-1 to CL-l accept instructions from the operator and issue instructions to the management device 300, process information provided by the management device 300, and present the information to the operator via a monitor or the like.

Figure 2 is a diagram showing an example of band allocation to base stations. In the embodiment, it is assumed that band A is allocated to company A's base station BSa, and band B is allocated to company B's base station BSb. Band A and band B are adjacent to each other, for example, in the Sub6 band. As shown in Figure 2(a), there is a risk of interference when a DL signal (D) in band A and a DL signal (D) in band B are transmitted simultaneously. The same is true for UL signals (U), as shown in Figure 2(b). In the embodiment, a technique for preventing interference will be described.

Figure 3 is a functional block diagram showing an example of a master station 100 and a slave station 200. In Figure 3, Company A's base station BSa and Company B's base station BSb are shown connected to the master station 100, but other base stations may also be connected in the same way.

The master station 100 includes a distributor (HYB) 11, a coupler (CPL) 12, a frequency conversion unit 13, a detection unit (DET) 14, an analog-to-digital converter (ADC) 15, a signal processing unit 16, a digital-to-analog converter (DAC) 17, a switch unit (SW) 18, a processor 19, and a base station interface (IF) 20.

Processor 19 controls and monitors each device. Base station IF 20 is an interface for communicating with base stations BSa, BSb, ..., BSm via interfaces such as RS232C, USB, and Ethernet (registered trademark).

The slave station 200 includes a signal processing unit 22 with a detection unit (DET) 21, a digital-to-analog converter (DAC) 23, a frequency conversion unit 24, a transmission amplifier (TPA) 25, a circulator 26, an antenna 27, a switch unit (SW) 28, a low-noise amplifier (LNA) 29, an analog-to-digital converter (ADC) 30, and a processor 31.

The operation of each functional block will be explained with respect to processing related to DL signals and processing related to UL signals.
<DL Processing of Master Station 100>
A wireless band DL signal from a base station BS passes through a distributor 11 and a coupler 12 and is input to a frequency converter 13. The coupler 12 branches off a portion of the DL signal and inputs it to a detector 14. The detector 14 detects the DL signal and notifies a processor 19 of the detected output.
The frequency conversion unit 13 performs radio reception processing and down-converts the DL signal to an IF (Intermediate Frequency) band. The DL signal converted to the IF band is converted from analog to digital by an AD converter 15 and sent to a signal processing unit 16. The signal processing unit 16 maps the digital signal to a TDD communication format between the master station 100 and the slave stations 200 for each operator, and transmits the digital signal to each slave station.

<UL Processing of Master Station 100>
The signal processing unit 16 extracts a digital signal from the slot of the UL signal from the RU 200 based on the communication format between the master station 100 and the slave stations 200. The signal processing unit 16 then combines the extracted digital signals for each slave station 200 on a carrier-by-carrier basis and sends the combined signal to the DA converter 17. The DA converter 17 converts the digital signal to analog and sends it to the frequency conversion unit 13. The frequency conversion unit 13 upconverts the analog signal to regenerate the UL signal. The UL signal is transmitted to the corresponding base station BS via the coupler 12, switch unit 18, and distributor 11. Part of the UL signal is branched off at the coupler 12 along the way and input to the detection unit 14.
Here, the processor 19 controls the on/off of the switch unit 18. As a result, the DL/UL signal route is switched in accordance with the DL slot timing and UL slot timing of the TDD signal.

<DL Processing of the Child Station 200>
The DL signal from the master station 100 is sent to a signal processing unit 22. The signal processing unit 22 extracts a digital signal from the slot of the DL signal based on the communication format between the master station 100 and the slave station 200. This digital signal is converted to an analog signal by a DA converter 23 and sent to a frequency conversion unit 24. The frequency conversion unit 24 upconverts the analog signal to match the transmission band of the air section and regenerates it into a DL signal. This DL signal is amplified to a transmission level by a transmission amplifier 25 and radiated from an antenna 27 via a circulator 26.

<UL Processing of Child Station 200>
A UL signal in a radio band from the mobile terminal 3 is transmitted from the antenna 27 to the LNA 29 via the circulator 26 and the switch unit 28. The switch unit 28 is controlled to be turned on/off by the processor 19 so as to switch the DL/UL signal route in accordance with the DL slot timing and UL slot timing of the TDD signal.
The LNA 29 amplifies the UL signal in the radio band and sends it to the frequency conversion unit 24. The frequency conversion unit 24 down-converts the UL signal to the IF band and sends it to the AD converter 30. The AD converter 30 converts the analog IF signal into a digital signal and sends it to the signal processing unit 22. The signal processing unit 22 maps the digital signal to a TDD communication format between the master station 100 and the slave stations 200 for each operator and transmits it to the master station 100. Here, the UL signal for each operator is detected by the detection unit 21 of the signal processing unit 22, and the level of the UL signal is detected.

The processor 19 of the master station 100 includes an operation control unit 19a and an inquiry unit 19b. The processor 31 of the slave station 200 includes a notification unit 31a. These are processing functions realized by the processor 19 executing a program embedded in memory (not shown).

The operation control unit 19a detects the loss of the DL signal in band A from the detection output of the detection unit 14, for example, when the level of the DL signal in band A falls below a predetermined threshold. The operation control unit 19a then allows asynchronous operation in band B during the period in which the loss of the DL signal in band A is detected. Asynchronous operation is an operation mode in which the TDD pattern in band B (A) is different from the TDD pattern in band A (B). In other words, the operation control unit 19a allows company B, which was synchronized with company A's TDD pattern before the loss of the DL signal in band A, to freely change the TDD pattern settings after the loss of the DL signal in band A.

The operation control unit 19a also detects the loss of the UL signal in band A from the detection output of the detection unit 21. The operation control unit 19a then allows asynchronous operation in band B during the period in which the loss of the UL signal in band A is detected. In other words, the operation control unit 19a allows company B, which was synchronized with company A's TDD pattern before the UL signal in band A was lost, to freely change the TDD pattern settings after the DL signal in band A is lost.

Here, the operation control unit 19a detects the loss of the UL signal in band A based on a notification from the slave station 200. That is, when the output of the detection unit 21 indicates that the level of the UL signal in band A falls below a predetermined threshold, for example, the notification unit 31a of the slave station 200 notifies the master station 100 that the loss of the uplink signal in band A has been detected.

The operation control unit 19a also makes a decision after querying the base station BS as to whether asynchronous operation is permitted. That is, when the query unit 19b detects the loss of the DL signal in band A, it notifies company B's base station BSb of this and receives a response. The operation control unit 19a determines whether asynchronous operation is permitted, that is, whether the operation mode can be switched, based on the result of this response.

Furthermore, when the inquiry unit 19b detects the loss of the UL signal in band A, it notifies company B's base station BSb of this and receives a response. Based on the result of this response, the operation control unit 19a decides whether to allow asynchronous operation, that is, whether to switch the operation mode.

4 is a diagram showing an example of a TDD pattern in synchronous operation. In synchronous operation, the frame format associated with base station BSa of company A and the frame format associated with base station BSb of company B are the same. The TDD pattern shown in FIG. 4 is referred to as TDD pattern 1 in the following description.
The switch unit 28 of the slave station 200 is turned on in synchronization with the UL slot and turned off in the DL slot. By controlling the switch unit 28, isolation in the DL section can be ensured and the impact on the processing system of the uplink signal can be reduced.

Figure 5 is a diagram explaining the state of the switches in the DL slot/UL slot. As shown in Figure 5(a), in frame #0, both Company A and Company B are in the DL section. In this section, switch units 18a and 18b of parent station 100 and switch unit 28 of child station 200 are both turned OFF. This allows DL signals to pass through but prevents UL signals from passing through.

On the other hand, as shown in Figure 5(b), in frame #2, both companies A and B are in the UL section. In this section, switch units 18a and 18b of parent station 100 and switch unit 28 of child station 200 are both turned ON. This allows UL signals to pass through, but prevents DL signals from passing through.

By the way, it is decided that the switching of switch units 18a, 18b, and 28 from OFF to ON is to be performed during the guard period of frame #1 (the time required to switch between DL and UL). This means that in multi-operator shared equipment, it is assumed that synchronization is maintained between multiple operators. In other words, with existing technology, asynchronous operation is generally difficult.

Therefore, a technology that enables asynchronous operation will be described below.
(effect)
6 and 7 are flowcharts showing an example of a processing procedure of the master station 100. In FIG. 6, the master station 100 monitors the loss of a DL signal from any base station (step S1) or the loss of a UL signal from any UE (step S2) in a loop of steps S1 to S3. As long as the master station 100 does not detect the loss of either a DL signal or a UL signal, it maintains synchronous operation by synchronizing the TDD patterns between the base stations (step S3). When the loss of a DL signal is detected (Yes in step S1) or the loss of a UL signal is detected (Yes in step S2), the processing procedure proceeds to operation switching (step S4) and jumps to step S41 in FIG. 7.

In Figure 7, the master station 100 inquires of the relevant base station whether or not it is possible to switch to asynchronous mode (step S41). For example, if the master station 100 detects the loss of Company A's DL signal, it notifies Company B's base station BSb of this via the base station interface 20 and inquires whether or not it is possible to switch to asynchronous operation. If the response to this inquiry is not permitted (No in step S42), the processing procedure returns to the caller and returns to the loop starting from step S1 in Figure 6.

If an OK response (OK) is received in response to the inquiry (Yes in step S42), the master station 100 exchanges control signals with the base station and changes the TDD pattern (step S43). For example, the TDD pattern is changed to increase the number of UL slots in response to a request from the UE to secure a larger uplink bandwidth. This operation continues until the lost DL signal resumes (Yes in step S44) or the lost UL signal resumes (Yes in step S45).
When the lost DL signal resumes or the lost UL signal resumes, the master station 100 performs processing to return to synchronous operation, and the processing returns to the loop starting from step S1 in FIG.

Figure 8 shows an example of a changed TDD pattern. As shown in Figure 8, company B's base station BSa can set a TDD pattern (TDD pattern 2) that is completely different from the TDD pattern (TDD pattern 1) associated with company A's base station BSa.

<Sequence when DL signal is lost>
9 is a sequence diagram showing an example of a processing procedure when a DL signal is lost. In the initial setting of FIG. 9, it is assumed that the master station 100 is operating in a synchronous operation mode with TDD pattern 1. At this time, the base station BSa of company A is communicating with the mobile terminal (UE) 3a with TDD pattern 1, and the base station BSb of company B is communicating with the mobile terminal (UE) 3b with TDD pattern 1.

In this state, let's say the input signal (DL) from company A's base station BSa disappears. The master station 100 then detects the loss of company A's DL signal from the output of the detection unit 14 (confirming that company A has stopped transmitting). The master station 100 then sends a TDD pattern change notification (company A stopped) to company B's base station BSb, notifying it that the input signal from company A has disappeared. Upon receiving this notification, company B's base station BSb checks whether the TDD pattern can be changed and sends a response including the result (Yes/No) back to the master station 100. Messages are exchanged between the master station 100 and company B's base station BSb via the base station interface 20.

If the TDD pattern can be changed, Company B's base station BSb replies with a response indicating that the change is possible (Yes), and the master station 100 then changes the TDD pattern in band B to, for example, TDD pattern 2 in Figure 8. This enables Company B's base station BSb and Company B's mobile terminal 3b to operate using an asynchronous TDD pattern (TDD pattern 2) via the master station 100.

Figure 10 shows the disappearance of the DL signal in band A. As shown in Figure 10(a), when the input signal (DL) from company A's base station BSa in slot #0 (Figure 8) disappears, asynchronous operation is achieved via the sequence in Figure 9. Even in this state, as shown in Figure 10(b), the uplink signals in slots #2 and #3 reach the master station 100 from the slave station 200. Here, the TDD pattern is changed by changing the OFF/ON switching timing of switches 18a and 18b in the master station 100 and switch 28 in the slave station 200.

Returning to Figure 9, we continue the explanation. In asynchronous operation mode, when company A's base station BSa resumes transmission using TDD pattern 1, the detection unit 14 of the master station 100 detects an input signal (DL) from company A's base station BSa. The master station 100 then immediately returns to synchronous operation mode and changes company B's TDD pattern back to TDD pattern 1. At this time, the master station 100 sends a TDD pattern change notification (company A resumed) to company B's base station BSb, notifying it that the input signal from company A has resumed. Upon receiving this notification, company B's base station BSb replies with a response and resumes synchronous operation using TDD pattern 1. Again, the change to TDD pattern 1 is achieved by changing the OFF/ON switching timing of switch units 18a, 18b, and 28.

<Sequence when UL signal is lost>
11 is a sequence diagram showing an example of a processing procedure when a UL signal is lost. As in FIG. 9, it is assumed that the master station 100 is operating in a synchronous operation mode with TDD pattern 1, the base station BSa of company A is communicating with the mobile terminal (UE) 3a with TDD pattern 1, and the base station BSb of company B is communicating with the mobile terminal (UE) 3b with TDD pattern 1.

In this state, let's say the input signal (UL) from company A's mobile terminal 3a disappears. The slave station 200 then detects the loss of company A's UL signal from the output of the detection unit 21 (no company A UL signal). Furthermore, the slave station 200 notifies the master station 100 that the UL signal from company A has disappeared by sending an UL status notification (no company A).

Upon receiving this, the master station 100 sends a TDD pattern change notification (no Company A UL signal) to Company B's base station BSb, notifying it that the UL signal from Company A's mobile terminal 3a has disappeared. Upon receiving this notification, Company B's base station BSb checks whether the TDD pattern can be changed and sends a response including the result (Yes/No) back to the master station 100. Messages are exchanged between the master station 100 and Company B's base station BSb via the base station interface 20.

If the TDD pattern can be changed, Company B's base station BSb replies with a response indicating that the change is possible (Yes), and the master station 100 then changes the TDD pattern in band B to, for example, TDD pattern 2. This enables Company B's base station BSb and Company B's mobile terminal 3b to operate using an asynchronous TDD pattern (TDD pattern 2) via the master station 100.

Figure 12 shows the disappearance of the UL signal in band A. When the input signal (UL) from company A's mobile terminal 3a in slot #2 (Figure 8) disappears, asynchronous operation is achieved via the sequence in Figure 11. The uplink signal in slot #2 travels from company B's mobile terminal 3b to company B's base station BSb via the slave station 200 and master station 100. Here too, the TDD pattern is changed by changing the OFF/ON switching timing of switches 18a and 18b in the master station 100 and switch 28 in the slave station 200.

Returning to Figure 11, we continue the explanation. In asynchronous operation mode, when company A's mobile terminal 3a resumes transmitting UL signals, the detection unit 21 of the slave station 200 detects the input signal (UL) from company A's mobile terminal 3a. The slave station 200 then notifies the master station 100 that UL communication from company A has resumed with an UL status notification (company A resume). The master station 100 then immediately returns to synchronous operation mode and changes company B's TDD pattern back to TDD pattern 1. At this time, the master station 100 transmits a TDD pattern change notification (company A resume) to company B's base station BSb, notifying it that the input signal from company A has resumed. Upon receiving this notification, company B's base station BSb replies with a response and resumes synchronous operation using TDD pattern 1. Again, the TDD pattern change is achieved by changing the OFF/ON switching timing of switches 18a and 18b of the master station 100 and switch 28 of the slave station 200.

As described above, in the embodiment, the master station 100 is equipped with a detection unit 14 that detects DL signals from base stations BSa and BSb, and if the DL signal from base station BSa is lost, the signal in band B related to base station BSb is operated in a pattern different from the TDD pattern used by base station BSa.

The slave station 200 is also equipped with a detection unit 21 that detects UL signals from the mobile terminal 3a, and if the UL signal from the mobile terminal 3a is lost, the slave station 200 notifies the master station 100 of this. Upon receiving this notification, the master station 100 operates the signals in band B related to base station BSb in a pattern different from the TDD pattern used by base station BSa.

In this way, it is possible to detect DL signals from operators that have been individually assigned bandwidth, and if they are absent, it is possible to switch to asynchronous operation. It is also possible to detect UL signals from each operator, and if they are absent, it is possible to switch to asynchronous operation. This control is possible only because it is a master station that serves as shared-operator equipment, accommodating the base stations of multiple operators. In other words, it is a function unique to shared-operator equipment that allows it to uniformly monitor the bandwidth usage status of each operator.

This functionality makes it possible to prevent interference between bands in an environment where the antenna 27 of the slave station 200 handles multiple bands. Furthermore, by enabling asynchronous operation, it becomes possible to flexibly respond to needs such as increasing the uplink bandwidth, thereby increasing the availability of the system.

For example, it becomes possible to connect operators that operate semi-synchronously and asynchronously to the same base station 100. This makes it possible to accommodate, for example, an operator that provides a service in which downlink bandwidth is important and an operator that provides a service in which uplink bandwidth is important, in the same base station 100. This makes it possible to provide flexible communication services for each operator.

Furthermore, with regard to downlink signals, the master station 100 can grasp the signal conditions of other operators, making it possible to select its own TDD pattern depending on the situation without affecting other operators. In other words, master stations operating base stations in the same series can switch their own TDD patterns without affecting base stations belonging to other series.

Currently, local 5G in the millimeter wave band (28.2-28.3 GHz band) is assumed to operate synchronously with other local 5G and nationwide 5G using the TDD method. According to an embodiment, it is possible to realize a variety of use cases using local 5G.

As a result, according to the embodiments, it is possible to eliminate the constraints associated with the shared use of infrastructure, thereby providing a distributed antenna system, master unit, remote unit, and operation control method with increased operational flexibility.

Note that this invention is not limited to the above-described embodiments. For example, if the transmission capacity is sufficient, the link connecting the master station and slave stations does not need to be limited to optical fiber. Also, the link connecting the base station and master station does not need to be limited to coaxial cable.

Furthermore, for example, in the embodiment, it was explained that the TDD pattern of company B is changed when a downlink signal or uplink signal related to company A is lost, but the same discussion holds true even if company A and company B are swapped. Of course, the master station (shared operator device) in the embodiment can also accommodate three or more operators, and the same discussion can be applied. Also, while the embodiment discussed asynchronous operation, in the case of quasi-synchronous operation, a similar solution can be achieved, for example, by reducing the output of the distributed antenna system.

Furthermore, the technology of the embodiment can be applied by exchanging information between distributed antenna systems operated by different entities.
13 is a block diagram for explaining switching between synchronous and asynchronous operation between base stations belonging to different master stations. In FIG. 13, it is assumed that a base station BSa of company A is connected to a master station 110, and a base station BSb of company B is connected to a master station 120. In this configuration, the master station 110 is provided with a master station interface (MU IF) 111 for communicating with the master station 120, and the master station 120 is provided with a master station interface 121 for communicating with the master station 120, so that the master stations can mutually notify each other of detected loss of DL signal and loss of UL signal. By providing interfaces 111 and 121 for exchanging information between the master stations in this way, it is possible to execute a sequence similar to that described above even in relationships with base stations accommodated by different master stations.

Furthermore, it is possible to aggregate detection information and control signals related to switching of operation modes in the management device 300, and have the management device 300 take the lead in controlling switching/returning of TDD patterns.

Although an embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its variations are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

3...Mobile terminal, 11...Distributor, 12...Coupler, 13...Frequency conversion unit, 14...Detection unit, 15...Analog/digital converter, 16...Signal processing unit, 17...Digital/analog converter, 18...Switch unit, 18a...Switch unit, 18b...Switch unit, 19...Processor, 19a...Operation control unit, 19b...Inquiry unit, 20...Base station interface, 21...Detection unit, 22...Signal processing unit, 23...Digital/analog converter, 24...Frequency conversion unit, 25...Transmitting amplifier, 26...Circulator, 27...Antenna, 28...Switch unit, 29...Low noise amplifier, 30...Analog/digital converter, 31...Processor, 31a...Notification unit, 100...Master station, 101...Base station connection unit, 102...Slave station connection unit, 200...Slave station, 200-1 to 200-n...Slave station, 300...Management device, CL-1 to CL-l...Client terminal.

Claims (12)

A master unit;
a remote unit having an antenna capable of covering a first band and a second band adjacent to the first band;
The master unit
a base station connection unit that can connect to a first base station that is assigned the first band and a second base station that is assigned the second band;
a slave station connection unit connectable to the remote unit;
a detection unit that detects a downlink signal in the first band;
a control unit that allows an operation mode in which a time division multiplexing pattern in the second band and a time division multiplexing pattern in the first band are different from each other during a period in which loss of a downlink signal in the first band is detected from the output of the detection unit. The master unit
an inquiry unit that notifies the second base station of a loss of the downlink signal in the first band and receives a response therefrom;
The distributed antenna system according to claim 1 , wherein the operation control unit determines whether or not to switch the operation mode based on a result of the response. A master unit;
a remote unit having an antenna capable of covering a first band and a second band adjacent to the first band;
The remote unit:
a detection unit that detects an uplink signal in the first band,
The master unit
a base station connection unit that can connect to a first base station that is assigned the first band and a second base station that is assigned the second band;
a slave station connection unit connectable to the remote unit;
a control unit that allows an operation mode in which a time division multiplexing pattern in the second band and a time division multiplexing pattern in the first band are different from each other during a period in which loss of an uplink signal in the first band is detected from the output of the detection unit. The remote unit:
a notification unit that notifies the master unit that a loss of the uplink signal in the first band has been detected from the output of the detection unit,
The distributed antenna system according to claim 3 , wherein the operation control unit allows the operation mode based on a notification from the remote unit. The master unit
an inquiry unit that notifies the second base station of a loss of the uplink signal in the first band and receives a response therefrom;
The distributed antenna system according to claim 3 , wherein the operation control unit determines whether or not to switch the operation mode based on a result of the response. a slave station connection unit connectable to a remote unit having an antenna capable of covering a first band and a second band adjacent to the first band;
a base station connection unit that can connect to a first base station that is assigned the first band and a second base station that is assigned the second band;
a detection unit that detects a downlink signal in the first band;
a master unit including an operation control unit that allows an operation mode in which the time division multiplexing pattern in the second band and the time division multiplexing pattern in the first band are different during a period in which loss of the downlink signal in the first band is detected from the output of the detection unit. an inquiry unit that notifies the second base station of a loss of the downlink signal in the first band and receives a response therefrom;
The master unit according to claim 6 , wherein the operation control unit determines whether or not to switch the operation mode based on a result of the response. a slave station connection unit connectable to a remote unit having an antenna capable of covering a first band and a second band adjacent to the first band;
a base station connection unit that can connect to a first base station that is assigned the first band and a second base station that is assigned the second band;
a master unit comprising an operation control unit that allows an operation mode in which a time division multiplexing pattern in the second band and a time division multiplexing pattern in the first band are different during a period in which loss of an uplink signal in the first band is detected. an inquiry unit that notifies the first base station of a loss of the uplink signal in the first band and receives a response therefrom;
The master unit according to claim 7 , wherein the operation control unit determines whether or not to switch the operation mode based on a result of the response. an interface connectable to a master unit connectable to a first base station assigned a first band and a second base station assigned a second band;
an antenna capable of covering the first band and the second band;
a detection unit that detects an uplink signal in the first band;
a notification unit that notifies the master unit that a loss of the uplink signal in the first band has been detected from the output of the detection unit. 1. A method for controlling operation of a distributed antenna system including a master unit and remote units each having an antenna capable of covering a first band and a second band adjacent to the first band, comprising:
The master unit:
An operation control method comprising a step of allowing an operation mode in which a time division multiplexing pattern in the second band and a time division multiplexing pattern in the first band are different during a period in which loss of a downlink signal in the first band is detected. 1. A method for controlling operation of a distributed antenna system including a master unit and remote units each having an antenna capable of covering a first band and a second band adjacent to the first band, comprising:
The master unit:
An operation control method comprising a step of allowing an operation mode in which a time division multiplexing pattern in the second band and a time division multiplexing pattern in the first band are different during a period in which loss of an uplink signal in the first band is detected.