Distributed antenna system

Abstract

To provide an improved distributed antenna system. [Solution] A distributed antenna system according to one embodiment uses 4G and 5G wireless communication waves It has an indoor wireless device that houses the transmitting and receiving antennas in a single enclosure.

Description

Technical Field

[0001] The present invention relates to communication network systems in 4G and 5G.

Background Art

[0002] A so-called communication network system in 5G is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0008] 1. Overview With the development of so-called 5G (fifth-generation mobile communication systems), the importance of communication is increasing. When a new communication system is developed, in order to introduce it at locations such as office buildings, hotels, and factories, it is necessary to install equipment that is compatible with the new communication system. However, the introduction of such equipment often places a significant burden on the site managers (e.g., office building owners) or users (e.g., office building tenants).

[0009] For example, with 5G, companies and local governments are permitted to individually build, operate, and use their own 5G networks (so-called local 5G). The core network servers necessary for operating a 5G network are expensive, and their construction and operation can be costly.

[0010] Alternatively, there may be requests to introduce multiple different wireless systems, such as 4G and 5G services provided by multiple mobile carriers, local 5G licensed by the building owner, regional BWA provided by cable operators, and even Wi-Fi. In this case, it is necessary to install separate antennas and wiring equipment for each wireless system, and securing installation space and increasing implementation costs become a significant burden for building owners.

[0011] A distributed antenna system (DAS) is a system that improves wireless signal coverage in places where wireless signals from base stations are difficult to reach, such as inside buildings, by distributing multiple small antennas and connecting them to a central base station or network. In DAS, it is sometimes required that 4G (LTE) and 5G coexist, but in related technologies, the systems for 4G and 5G are provided as separate components. For example, in local 5G, separate housings are used for the radio unit (RU) (hereinafter referred to as base station RU for convenience) for 4G and 5G. There are several reasons for this, but one reason is that, for example, 4G uses a wide frequency band from 700MHz to 3.4GHz, and if this were to be contained in a single housing for both the 4G and 5G systems, power consumption would be high. However, increasing the number of housings increases the installation space, which leads to increased costs.

[0012] Figure 1 shows an overview of the DAS (Data Transfer System). From the station building to the mobile carrier radio equipment, these are the assets of each mobile carrier. These are installed by each carrier. If there are, for example, four carriers, each of these four companies will install their own equipment. The MU (Master Unit) is the signal processing unit of the DAS, receiving signals from the outside and distributing them to multiple RUs (Remote Units). Each RU transmits signals to multiple antennas (the base station RUs mentioned above). The signals received by each antenna follow the reverse path.

[0013] Therefore, the inventors of the present application have come up with a configuration in which, in DAS (specifically, in the base station RU), radio waves (wireless communication waves) in all frequency bands of 4G and 5G are not transmitted and received, but only radio waves in specific limited frequency bands are transmitted and received. More specifically, considering the balance between the effect of improving the communication environment indoors and the miniaturization and low power consumption of the device, they have come up with a configuration that technically and strategically selects to transmit and receive only radio waves in specific frequency bands. In this embodiment, the frequency bands supported by DAS are, as an example, only the following three frequency bands, and other frequency bands are not supported. 4G: 1.7 GHz band (FDD) 4G: 2.1 GHz band (FDD) 5G: 3.6 - 4.0 GHz band (TDD)

[0014] Regarding 5G communication, when the frequency bands are classified into low band (Sub-1 GHz band: 600 MHz - 1 GHz), mid band (Sub-6 GHz band: 1 GHz - 6 GHz), and high band (millimeter wave band: 24 GHz - 100 GHz), it means supporting only some frequency bands in the mid band. This is based on the idea that for low-band radio waves, since the radio waves from the outside are more likely to reach indoors without using an indoor base station RU than mid-band and higher-band radio waves, they are excluded from the support range in the base station RU. The same applies to 4G communication.

[0015] More specifically, the selection of the above frequency bands is based on the following technical ideas. First, the frequency bands to be supported by the base station RU are limited to those where radio waves from the outside are likely to attenuate and difficult to reach indoors. For example, frequency bands lower than the 1.7 GHz band (such as the 700 MHz band) are excluded from the support targets of indoor wireless devices because they are relatively easy to penetrate into buildings due to their physical characteristics. This narrows down the frequency bands to be dealt with, avoids the complication of the circuit configuration inside the device, and realizes the miniaturization of the housing and low power consumption.

[0016] Secondly, from the narrowed-down frequency bands, we selected the most valuable frequency bands that would maximize the effectiveness of infrastructure sharing. Specifically, for 4G communication, we selected the 1.7GHz and 2.1GHz bands for the following reasons. (1) Importance in data communication: These frequency bands can secure a wider bandwidth compared to other 4G frequency bands and are highly likely to be used for high-speed, high-capacity data communication. (2) Support for voice call services: The system supports VoLTE (Voice over LTE), the main voice call technology in current 4G networks, which is essential for providing stable voice services as well as data communication. (3) Commonality among Japanese domestic telecommunications carriers: The 1.7GHz band is available for use by all four domestic carriers, and the 2.1GHz band is an extremely important frequency band used by the three major companies internationally as "Band 1". By supporting these highly common frequency bands, it is possible to maximize the benefits of infrastructure sharing, which allows a single device to share radio waves from multiple carriers.

[0017] Similarly, with regard to 5G communication, the 3.7GHz band has been selected from the mid-band (Sub-6GHz band), which, while less likely to penetrate indoors than the millimeter-wave band, is likely to become the mainstream in the future. In this way, the DAS of this embodiment does not simply limit the frequency band, but supports only the frequency bands that have been rationally selected by considering multiple technical aspects such as the physical characteristics of radio waves, importance in communication services, and commonality in business, thereby achieving both miniaturization and cost reduction of the device and the formation of a high-quality indoor communication area.

[0018] In order to integrate 4G and 5G communication into a single housing in the base station RU according to this embodiment, there were further technical challenges to overcome. This stems from the fundamental difference in the duplexing methods employed by the two. Specifically, the 4G communication supported by this embodiment employs the FDD (Frequency Division Duplex) method, which uses different frequencies for transmission and reception. On the other hand, 5G communication employs the TDD (Time Division Duplex) method, which switches between transmission and reception in extremely short periods of time.

[0019] The FDD and TDD systems use different synchronization systems for correctly transmitting and receiving wireless signals. In the TDD system, strict time synchronization between the base station and the terminal is essential, while in the FDD system, frequency-based separation is fundamental. Therefore, if these two systems are simply placed side by side in a single enclosure, even if the respective RF circuits (radio equipment parts) are physically separated, unwanted radio waves (spurious signals) leaking from one circuit can interfere with the other, causing significant degradation of communication quality or even communication failure. In particular, if the transmission signal of the FDD system overlaps with the reception timing of the TDD system, there is a risk that the reception sensitivity will be significantly impaired.

[0020] This difference in duplexing methods also manifests as differences in the physical circuit configuration of the RF front-end module (RF FEM) connected to the antenna. Generally, in the FDD method, a duplexer is used to permanently separate the transmitted and received signals based on frequency. On the other hand, in the TDD method, an RF switch is used to rapidly switch the transmission and reception timings, eliminating the need for a duplexer. However, as shown in Figure 7 below, the base station RU according to this embodiment employs an RF switch instead of a duplexer even in the 4G RFFEM that uses the FDD method, and the FPGA performs precise timing control, thereby achieving circuit commonality and miniaturization. In this way, this embodiment solves the technical challenge of densely mounting circuits of different duplexing methods within a single chassis without interfering with each other.

[0021] Therefore, to solve this interference problem, the present invention employs digital signal processing technology including an FPGA (Field-Programmable Gate Array). Specifically, the indoor wireless device (RU) and master unit (MU) shown in the drawings are equipped with an RFIC (Radio Frequency Integrated Circuit) that converts RF signals and digital signals to each other, and an FPGA that performs digital signal processing.

[0022] In this embodiment, the FPGA plays a role in completely separating and controlling the signal processing systems for 4G (FDD) and 5G (TDD), not only in terms of physical circuit layout but also logically in the digital domain. The received signal input from the antenna is quickly converted into a digital signal by the RFIC and taken into the FPGA. The FPGA processes the FDD signal and the TDD signal independently using algorithms appropriate to each system. Similarly, during transmission, the FDD and TDD digital signals generated and processed within the FPGA are converted into analog RF signals via the RFIC.

[0023] In this way, by performing most of the signal processing in the digital domain and logically separating and controlling both methods using an FPGA, an extremely high level of isolation that would be difficult to achieve with physical shielding alone is realized. As a result, even in a physically close environment such as within a single enclosure, the FDD method and the TDD method can coexist stably without interfering with each other. This FPGA-based solution is the key technology for realizing a high-performance 4G / 5G coexisting indoor wireless device in a small and low-power enclosure.

[0024] 2. Embodiments Figure 13 shows an overview of a communication system 2 according to one embodiment. The communication system 2 reduces the cost of its introduction by sharing physical lines laid within a base station across networks with different standards or service providers. One embodiment relates to so-called infrastructure sharing.

[0025] Communication System 2 can be described as an example of an in-site communication network in the communication network shown in Figure 10. First, the configuration related to 5G communication will be explained. Communication System 2 has a master unit, an optical concentrator, a repeater, a splitter, and slave units. These are installed within the site (for example, inside a building or on the premises).

[0026] A 5G carrier radio is a device that transmits and receives radio signals specific to each carrier. The base station end of the carrier radio is connected to a base station, and the outside end is connected to the telecommunications company's central office. Communication system 2 communicates with the external 5G network via the carrier radio. The communication path within the base station is mainly optical fiber (i.e., optical fiber; an example of a physical line). The base station is divided into multiple areas (e.g., multiple floors). Optical fiber lines are laid to each area via repeaters. A slave unit is connected to the end of the optical fiber line. A 5G antenna is connected to the slave unit. The 5G antenna creates a 5G access area within the base station (i.e., within the building).

[0027] The master unit is connected to 5G carrier radios from multiple carriers (in the diagram, companies A, B, and C). However, instead of each carrier laying its own optical fiber lines, a single set of optical fiber lines laid within the base station is shared by multiple carriers. Although the master unit and slave units are physically connected by a common line, they are logically divided into multiple logical networks. The signals from multiple carriers are physically transmitted along the same path, but logically they are transmitted along divided paths. Network slices used in 5G communication are used as logical networks. In this example, the logical network includes three slices: slice S[A] which transmits the signal from company A, slice S[B] which transmits the signal from company B, and slice S[C] which transmits the signal from company C. The slave units output the signals received from the optical fiber lines to the 5G antenna. The 5G antenna is shared by multiple carriers. Alternatively, each carrier may use its own dedicated 5G antenna.

[0028] The same applies to both downlink and uplink. The 5G antenna outputs the signal received from the terminal to the slave unit. The slave unit outputs the wireless signal from company A to slice S[A], the wireless signal from company B to slice S[B], and the wireless signal from company C to slice S[C]. These signals are physically transmitted over a common optical line. The base station outputs the signal received from the optical line to the 5G carrier radio. The base station outputs the signal transmitted via slice S[A] to 5G carrier A radio, the signal transmitted via slice S[B] to 5G carrier B radio, and the signal transmitted via slice S[C] to 5G carrier C radio. Each 5G carrier radio outputs its signal to its own network.

[0029] Next, the configuration related to the wireless LAN will be explained. Within the base station, an optical concentrator is installed downstream of the base station. As seen from outside the base station, the optical concentrator is a device that superimposes inputs from multiple optical lines onto a single optical line. Signals from the base station and signals from the external network (Internet or closed network) are input to the optical concentrator via the optical line. The optical concentrator superimposes these signals and outputs them to the optical line within the base station. Wireless LAN signals are transmitted within the base station via the same optical line that transmits 5G communication. In this example, the base station and the optical concentrator are devices housed in a single enclosure.

[0030] A splitter is installed in part of the optical fiber line. A splitter is a device that divides the signal being transmitted through the optical fiber line into multiple optical fiber lines. For example, a splitter is installed between a repeater and a client device. The output of the splitter is divided into an output for 5G communication and an output for wireless LAN communication. An optical termination device (e.g., ONU, Optical Network Unit) is connected to the optical fiber line of the wireless LAN communication output. A WiFi antenna is connected to the optical termination device. A slice S[D] is formed between the optical concentrator and the optical termination device. Wireless LAN signals are transmitted through slice S[D].

[0031] Next, the configuration for local 5G will be explained. The output of the splitter is branched into outputs for 5G communication, Wi-Fi communication, and local 5G. CU, DU, and RU are connected to the optical line of the local 5G output. A slice S[E] is formed between the optical concentrator and the RU. Local 5G signals are transmitted through slice S[E]. The communication equipment described above is installed within the site.

[0032] Furthermore, the network configuration within a site illustrated in Figure 11 of the related technology corresponds to the configuration in the example in Figure 13, with the 5G communication configuration and the wireless LAN configuration omitted. In other words, Figure 11 shows an example of connecting a network slice formed within site A and a network slice formed within site B with a logical network of a closed network.

[0033] Communication system 2 is connected to core network server 5GC via the internet or a private network (more specifically, an SD-WAN private network). Core network server 5GC controls the generation of network slices for communication system 2 and communication through those network slices. Core network server 5GC is provided by a service provider that establishes the communication environment within the site. This service provider may be a different service provider from the one providing 5G communication.

[0034] Figure 14 illustrates the functional configuration of communication system 2. The core network server 5GC has NSSF, AUSF, UDM, UDR, AMF, SMF, PCF, and NRF. The core network server 5GC also has UPF-1, UPF-2, and UPF-3. NSSF (Network Slice Selection Function) selects an SMF for each slice. AUSF (Authentication Server Function) authenticates subscribers (i.e., acts as an authentication server). UDM (Unified Data Management) holds subscriber-related information. UDR (Unified Data Repository) holds subscriber status. AMF (Access and Mobility Management Function) handles subscriber authentication, security, and terminal location management. SMF (Session Management Function) manages sessions. SMF is an example of a storage means that stores information related to a logical network using communication equipment and physical lines installed within a site, and a control means that uses the information stored in the storage means to control the communication equipment so that terminals connected to the communication equipment at the site communicate through that logical network. The PCF (Policy Control Function) performs policy control. The NRF (Network Repository Function) registers services for each network function. The UPF (User Plane Function) handles packet forwarding of user data. In this example, three UPFs are illustrated: UPF-1, UPF-2, and UPF-3. Although not shown in the illustration, the core network server 5GC also has an NEF (Network Exposure Function). The NEF provides control NFs to external parties via an API, for example, to detect user movement or control communications. These are the functions of the core network server 5GC. The related technology core network server 5GC has a similar functional configuration.The related technology and one embodiment share the commonality of controlling the communication network of a site via multiple network slicings (logical networks). In addition, in the related technology, communication within each site may be divided into multiple network slices.

[0035] This diagram shows three logical paths corresponding to three different communication standards. The first logical path, indicated as slice A in the diagram, is the logical path for 5G communication. In the example in Figure 13, this logical path is shown to be divided into three network slices depending on the number of communication carriers. The second logical path, indicated as slice B in the diagram, is the logical path for wireless LAN. The third logical path, indicated as slice C in the diagram, is the logical path for local 5G.

[0036] The AMF controls the AGF / FMIF / FRG for 5G communication, the N3IWF for wireless LAN, and the gNB for local 5G, respectively. The SMF controls the UPF-1 for 5G communication, the UPF-2 for wireless LAN, and the UPF-3 for local 5G, respectively. In this example, the N3IWF is implemented in the SD-WAN router. That is, the communication equipment at the site includes an SD-WAN router with the N31WF implemented.

[0037] This section describes an example where communication system 2 supports three communication standards: 5G communication, Wi-Fi, and local 5G. However, the communication standards supported by communication system 2 are not limited to this combination of three. Some or all of these communication standards may be replaced with other communication standards. Communication system 2 may support one, two, or four or more communication standards. Communication system 2 may support only one communication standard and support multiple communication carriers. In other words, multiple network slices may correspond to multiple communication carriers. The number of coexisting network slices may increase to any extent permitted by the standard.

[0038] According to this example, the person responsible for setting up the communication environment at a location (for example, the building owner) can install fiber optic lines within the location and then, by dividing these lines into multiple logical networks, support for multiple communication standards or carriers can be added later. Even if a new communication standard emerges in the future, as in the example in Figure 13, equipment compatible with the new communication standard can be connected downstream of the splitter, and additional network slices can be configured for communication of that communication standard, thereby enabling support for the new communication.

[0039] The Core Network Server 5GC is a server implemented or installed in the cloud. The Core Network Server 5GC may also be physically composed of a single device. In the future, if new standards such as 6G emerge, the name "5G Core Network Server" may be changed, in which case the functions corresponding to the 5G Core Network Server in the new standard will correspond to the 5G Core Network Server of the present invention.

[0040] With the increasing capacity of communications, the physical capacity (volume) of the physical lines used to transmit those communications has become a problem. For example, if one tries to achieve a 100GB communication environment, using Ethernet cables would result in cables that are too large to physically run through conduits. Therefore, laying fiber optic lines within the site becomes essential, but laying dedicated fiber optic lines for each communication standard or carrier would impose a significant cost burden on the installer. According to this embodiment, physical lines can be shared by multiple communication standards or carriers, making it easier to implement communication environments within a site.

[0041] 3. DAS Configuration To realize advanced and flexible communication network systems such as the related technologies and one embodiment described above, it is essential that the devices providing wireless access at the end of the network, i.e., base station RUs, are high-performance and easy to install. In particular, the ability to efficiently handle radio waves from multiple communication methods (4G and 5G) and multiple carriers is required. Below, we will describe in detail the specific device configuration of the base station RU and the DAS including it that support such advanced network systems according to this disclosure.

[0042] Figure 2 shows a schematic diagram of the DAS according to this embodiment. This DAS has a master unit (MU) and a base station RU as its basic configuration. As shown in Figure 2, when increasing the number of antennas in a large-scale facility, it is also possible to install a hub unit (HU) between the MU and RU as a relay device for splitting the signal. Figure 3 shows a front view of the master unit MU. Figure 4 shows a four-view drawing of the base station RU, and Figure 5 shows a front view of the base station RU. Figure 6 shows an enlarged view of the interface section of the base station RU.

[0043] The base station RU has a so-called 2T2R antenna common to the 1.7GHz and 2.1GHz bands, and a 4T4R antenna port for the 3.7GHz band (3.6~4.0GHz band).

[0044] Figure 7 is a block diagram illustrating the internal configuration of a base station RU. The base station RU converts between optical signals and RF signals and transmits and receives 4G (FDD) and 5G (TDD) wireless communication waves. The base station RU is broadly composed of a DTU (Digital Transceiver Unit) which is responsible for digital signal processing and conversion to optical signals, an RF front-end module (RFFEM) which amplifies RF signals and switches between transmission and reception, and a PSU (Power Supply Unit) which supplies power to the entire device.

[0045] In the downlink, optical signals transmitted from the host device (HU) via fiber optic cables are converted into electrical signals by SFP modules (SFPA, SFPB) and input to the FPGA. The FPGA logically separates the 4G signal system and the 5G signal system in the digital domain and outputs each signal to the corresponding RFIC. Each RFIC converts the input digital signal into an analog RF signal.

[0046] RF signals corresponding to 4G communication in the 1.7GHz and 2.1GHz bands are input to the 1.7G / 2.1G RFFEM. The signals are amplified by multiple amplifiers (AMPs), output to the 1.7G / 2.1G multiplexer via an RF switch (RFSW) and coupler (CPL), and then output from the antennas (ANT0, ANT1).

[0047] RF signals for 5G communication in the 3.7GHz band are input to a 3.7G RF FEM. The signals are amplified by multiple amplifiers (AMPs), pass through an RF switch (RFSW) and coupler (CPL), and then through a 3.7G band pass filter (BPF) to remove unwanted frequency components before being transmitted from antennas (ANT0~3).

[0048] In the uplink, the signals received by each antenna follow the reverse path of the downlink. That is, they are amplified by a low-noise amplifier (LNA) within each RF FEM, converted into a digital signal by an RFIC, and processed by an FPGA. Finally, they are converted into an optical signal by an SFP module and transmitted to the HU.

[0049] A Phase-Locked Loop (PLL) supplies a high-precision clock signal that serves as the operating reference for digital circuits such as FPGAs and RFICs, maintaining synchronization throughout the entire system. The Power Supply Unit (PSU) receives power from an external AC power source (ACIN), converts it to the DC voltage (DC29V) required within the device, and supplies it to each component. In this way, an FPGA implemented within a single enclosure comprehensively controls both 4G (FDD) and 5G (TDD) signal systems, which use different methods, thereby suppressing mutual interference and enabling stable communication. This FPGA-centered digital signal processing circuit is an example of a digital signal processing unit.

[0050] Figure 8 is a block diagram illustrating the internal configuration of the master unit MU. The master unit MU receives 4G and 5G RF signals from multiple different wireless systems, such as mobile carrier radios, converts them into digital signals, and then distributes them as optical signals to multiple hub units HU.

[0051] In the downlink, the RF signals input from each carrier's radio are split into two systems according to the frequency band. 4G (FDD) signals in the 1.7GHz and 2.1GHz bands are distributed to each carrier by a power divider and then input to a 1.7G / 2.1GRFFEM. Within this RFFEM, the signals pass through a duplexer that performs transmit / receive separation using the FDD method, are amplified by an amplifier (AMP), and then converted into digital signals by an RFIC.

[0052] Meanwhile, 5G (TDD) signals in the 3.7GHz band are similarly distributed by a power divider before being input to a 3.7G RFFEM. The signal passes through a bandpass filter (BPF) to remove unwanted frequency components, is amplified by an amplifier (AMP), and then converted into a digital signal by another RFIC.

[0053] The digital signals output from these two RFIC systems are input to the FPGA within the DTU (Digital Transceiver Unit). The FPGA processes the signals of the different 4G (FDD) and 5G (TDD) methods using independent signal processing systems. The PLL and Source Clock (Source CLK) supply the reference clock signals necessary for FPGA operation, and the Synchronization Module maintains the strict synchronization required, especially for the TDD method.

[0054] Digital signals processed by the FPGA are converted into optical signals by SFP modules (SFP A, SFP B) and transmitted to up to six hub units (HU#1 to HU#6). In the uplink, signals are processed in the reverse direction.

[0055] The PSU receives power from an external AC power source (AC IN) and generates the required DC voltage (DC 12V, DC 5.5V) for the device, supplying it to each component. The FAN cools the heat generated inside the device, ensuring stable operation.

[0056] The indoor wireless device (RU) according to this embodiment incorporates several distinctive features in the physical structure of its enclosure, taking into consideration its installation environment and long-term stable operation. Firstly, it features a fanless structure and heat dissipation design to improve reliability and ensure flexibility in installation location. Indoor wireless devices (RUs) may be installed in places where frequent maintenance is difficult, such as in the ceiling space of a building. In such environments, cooling fans, which are physical drive components, can be a potential cause of failure and contribute to a decrease in the reliability of the device. Therefore, the RU of this embodiment employs a fanless structure without a cooling fan. Furthermore, in order to efficiently dissipate the heat generated internally despite the fanless structure, numerous heat dissipation fins are integrally molded onto the surface of the enclosure, as shown in Figures 4 and 5. These heat dissipation fins increase the surface area of ​​the enclosure, ensuring high heat dissipation performance through natural air cooling and enabling stable operation of the device. The adoption of this fanless structure also contributes to weight reduction (for example, the device weight is suppressed to about 17 kg), and also has the effect of improving the ease of installation in places such as ceiling space.

[0057] Secondly, it has a robust interface structure to maintain communication reliability. In particular, the connection part (SFP module) of the optical fiber cable used to connect to the HU (hub unit), which is a higher-level device, is vulnerable to physical shocks and stresses from the outside. Therefore, as shown in Figure 6, the base station RU of this embodiment has a dedicated compartment in the shape of a "small box" (hereinafter referred to as the "housing section") inside the cover that protects the interface section, which houses the SFP module to which the optical fiber cable is connected and the surrounding interface terminals (hereinafter collectively referred to as the "optical connector section"). The optical fiber cable is drawn into this housing section and then connected to the optical connector section. This prevents the SFP module itself from being directly exposed to the outside, protects the connection part from unexpected shocks during installation or operation, dust intrusion, or excessive tension on the cable, and significantly reduces the risk of communication interruption.

[0058] Furthermore, to ensure a stable power supply, a robust screw-type connector is used for connecting the power cable. This prevents the power cable from becoming detached due to vibration or accidental contact, thereby increasing the reliability of power supply to the device. Due to these structural features, the indoor wireless device (RU) of this embodiment can operate stably for long periods of time in various environments.

[0059] The distributed antenna system of this embodiment can further be equipped with a remote monitoring system (RMS) to dramatically improve its operational maintainability. Conventionally, monitoring of this type of system was generally performed from on-site monitoring terminals using dedicated lines or proprietary protocols. In contrast, the RMS of this embodiment has a remote monitoring server built on the cloud.

[0060] The master units (MUs) installed at each location connect to a remote monitoring server in the cloud via an encrypted and secure communication channel using HTTPS, a standard internet protocol. This allows operators to monitor and control the status of the entire system anytime, anywhere, through a web browser, without being tied to a specific location.

[0061] The monitoring scope extends beyond the operational status of individual devices such as MUs, HUs, and RUs. It also allows for real-time monitoring of parameters directly related to communication quality, such as input / output levels of signals received from the carrier and the output status of wireless signals from each antenna. Furthermore, it enables advanced control, including remote firmware upgrades and software-based temporary suspension of services on specific frequency bands. This system also features multi-tenancy functionality, designed for situations where multiple facility owners share the system, providing each owner with an independent monitoring environment. These features enable rapid fault response and efficient system operation.

[0062] 4. Other Embodiments The present invention is not limited to the embodiments described above, and various modifications are possible. Several modifications are described below. Two or more of the modifications described below may be used in combination.

[0063] The combination of frequency bands supported by the base station RU is not limited to those exemplified in the embodiments. Any combination is acceptable as long as it includes at least one frequency band from 4G and at least one frequency band from 5G. From the viewpoint of equipment configuration, it is preferable to implement one or two frequency bands from the midband frequency bands for both 4G and 5G.

[0064] The type of physical line is not limited to those exemplified in the embodiment. A coaxial cable may be used instead of an optical fiber line, or vice versa.

[0065] The functions of the core network server 5GC described in the embodiment (Figure 14) are merely illustrative and not limiting. Some of the illustrated functions may be omitted, or other functions may be added.

[0066] One aspect of the present disclosure provides a communication network system comprising: a first local 5G base station installed at a first site; a first router installed at the first site and communicating with the first local 5G base station; a first remote station controlling the first local 5G base station; a first aggregation base station controlling the first remote station; a second local 5G base station installed at a second site separate from the first site; a second router installed at the second site and communicating with the second local 5G base station; a second remote station controlling the second local 5G base station; a second aggregation base station controlling the second remote station; a 5G core network server installed in the cloud and controlling the first aggregation base station and the second aggregation base station; a plurality of slices, including a first slice, included in the physical network from the first local 5G base station to the first router; a plurality of slices, including a second slice, included in the physical network from the second local 5G base station to the second router; and a closed network connected to the first router and the second router, connecting the first slice and the second slice.

[0067] The first remote station and the first aggregation base station may be installed at the first location, and the second remote station and the second aggregation base station may be installed at the second location.

[0068] The first remote station, the first aggregation base station, the second remote station, and the second aggregation base station may be installed in the cloud.

[0069] The aforementioned private network may be an SD-WAN private network.

[0070] The 5G core network server may control the first router and the second router to generate the first slice and the second slice in response to a predetermined event.

[0071] The 5G core network server may have a database that records information regarding the settings of a terminal at the first location, a terminal at the second location, and the settings of a slice when communicating between the terminal at the first location and the terminal at the second location, and when a predetermined event occurs, the 5G core network server may control the first router and the second router to refer to the database and generate the first slice and the second slice based on the settings.

[0072] 5. Others Figure 9 illustrates the configuration of a 5G network related to the relevant technologies. The DAS according to the above embodiment can also coexist with a local 5G network. The local 5G network has a base station RU, a router RT, and a core network server 5GC at each location. This configuration has the challenges of high initial deployment costs and the need for advanced operational skills. In particular, the introduction of the core network server 5GC can cost tens of millions of yen, which is a major obstacle for companies or organizations that wish to implement it.

[0073] Figure 10 illustrates the configuration of a communication network related to the relevant technology. This communication network includes a local 5G network. In this example, the core network server 5GC is implemented in the cloud and shared by multiple local 5G networks. By sharing the core network server 5GC among multiple local 5G networks in this way, the deployment cost of the local 5G network can be reduced.

[0074] Figure 11 illustrates an example of an inter-site communication system related to the relevant technology. Here, we consider communication between two sites, site A and site B. Sites A and B each have a base station RU, a remote station / aggregation base station CU / DU, and a router RT. Here, the router RT is a router compatible with SD-WAN (Software-defined Wide Area Network). Within each site, the physical network from the base station RU to the router RT is divided into multiple slices (i.e., multiple logical networks) (so-called network slicing). At site A, the physical network between the base station RU[A] and the router RT[A] is divided into multiple slices, including slice A[1]. At site B, the physical network between the base station RU[B] and the router RT[B] is divided into multiple slices, including slice B[1]. The base station RU, remote station / aggregation base station CU / DU, and router RT at each site are examples of communication equipment installed at that site. Here, the remote station / aggregated base station CU / DU schematically represents a configuration in which the DU (Distributed Unit) and CU (Centralized Unit), which are the functional parts of a 5G base station, are integrated or individually arranged.

[0075] Routers RT[A] and RT[B] are connected by SD-WAN. That is, slices A[1] and B[1] are connected by SD-WAN. With this configuration, all communication between sites is logically isolated from other networks. This makes it possible to form a secure and high-speed communication network between site A and site B. Note that the private network connecting routers RT[A] and RT[B] is not limited to SD-WAN. The private network connecting routers RT[A] and RT[B] may be other private networks such as dedicated lines, wide-area Ethernet, or IP-VPN (Virtual Private Network).

[0076] Furthermore, at least one of routers RT[A] and RT[B] may be connected to a Data Network (DN) such as the Internet via a User Plane Function (UPF). Since communication between terminals at a site and the DN uses a different slice than communication between sites, it does not affect communication between sites.

[0077] This SD-WAN is connected to the Core Network Server 5GC, which is implemented on the cloud. The Core Network Server 5GC controls the remote stations / aggregation base stations CU / DU for each of sites A and B.

[0078] Figure 12 shows another example of an inter-site communication system. Sites A and B each have a base station RU and a router RT. In contrast to the example in Figure 11, the difference is that the remote station / aggregated base station CU / DU is implemented on the cloud, and there is no remote station / aggregated base station CU / DU at each site. Within each site, the physical network from the base station RU to the router RT is divided into multiple slices. At site A, the physical network between base station RU[A] and router RT[A] is divided into multiple slices, including slice A[1]. At site B, the physical network between base station RU[B] and router RT[B] is divided into multiple slices, including slice B[1].

[0079] Router RT[A] and Router RT[B] are connected via SD-WAN. That is, slice A[1] and slice B[1] are connected via SD-WAN. This configuration ensures that all communication between sites is logically isolated from other networks. This allows for the creation of a secure and high-speed communication network between site A and site B.

[0080] This SD-WAN is connected to remote stations / aggregation base stations CU / DU implemented on the cloud. Furthermore, a core network server 5GC is also implemented on the cloud. The core network server 5GC controls the remote stations / aggregation base stations CU / DU[A] and CU / DU[B]. Alternatively, a UPF may be implemented on the cloud, and a slice separate from the one used for inter-site communication may be connected to a DN such as the internet.

[0081] In the examples shown in Figures 11 and 12, terminal UE[A] at site A and terminal UE[B] at site B can communicate securely using a local 5G network slice and satisfy the requirements (or settings) according to their application. Slices A[1] and B[1] between terminal UE[A] and terminal UE[B] may be formed at all times or may be dynamically generated in response to a predetermined event. In one example, this event is that router RT[A] has received an access request from terminal UE[A] to terminal UE[B]. When router RT[A] receives an access request from terminal UE[A] to terminal UE[B], the core network server 5GC reads the slice settings for communication between terminal UE[A] and terminal UE[B] from a database stored in the storage means. The core network server 5GC controls routers RT[A] and RT[B] to generate slices according to these settings. Routers RT[A] and RT[B] generate slices A[1] and B[1] according to instructions from the core network server 5GC. Once slices A[1] and B[1] are generated, the core network server 5GC controls the SD-WAN to connect slices A[1] and B[1].

[0082] As described above, this embodiment enables the provision of secure, flexible, and easy-to-operate intra- and inter-site communication services by connecting sites with an SD-WAN private network. For example, if site A is a local private hospital and site B is a university hospital, a doctor at site A can make a diagnosis while checking the results of examinations (e.g., images in diagnostic imaging) performed using examination equipment only available at site B in real time. [Explanation of symbols]

[0083] RU…Base station, CU / DU…Remote station / aggregation base station, RT…Router, 5GC…Core network server

Claims

1. A distributed antenna system having an indoor wireless device that houses antenna ports for transmitting and receiving 4G and 5G wireless communication waves in a single enclosure.

2. The aforementioned indoor wireless device supports the following frequency bands: 1.7 GHz and 2.1 GHz bands for 4G communication systems, and 3.7 GHz band for 5G communication systems. The distributed antenna system according to claim 1.

3. The indoor wireless device has a digital signal processing unit that suppresses interference between signals of both types by logically separating and processing the signal processing system of the 4G communication method (FDD method) and the signal processing system of the 5G communication method (TDD method) in the digital domain. The distributed antenna system according to claim 1.

4. The indoor wireless device uses an RF switch instead of a duplexer to separate the transmitted signal and the received signal in the signal system of the 4G communication system. The distributed antenna system according to claim 3.

5. The indoor wireless device has heat dissipation fins provided on the surface of the housing. The distributed antenna system according to claim 1.

6. The indoor wireless device has a fanless structure without a cooling fan. The distributed antenna system according to claim 5.

7. The aforementioned indoor wireless device is The optical connector section to which the optical fiber cable is connected, A housing is provided inside the housing, and the optical connector is housed inside the cover that protects the interface section. A distributed antenna system according to claim 1, having the following features.

8. The distributed antenna system further includes a remote monitoring server that monitors the operating status of the indoor wireless device and master unit that constitute the distributed antenna system, The master unit and the remote monitoring server are connected using a communication protocol via the Internet. The distributed antenna system according to claim 1.

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