Distributed antenna system

Abstract

To provide an improved distributed antenna system.SOLUTION: A distributed antenna system (DAS) according to one embodiment includes an indoor radio device in which antennas for transmitting and receiving radio communication waves in 4G and 5G are accommodated in one housing. In the DAS, a RadioUnit (RU) does not transmit and receive radio waves in all frequency bands in 4G and 5G, but transmits and receives only radio waves in a specific limited frequency band.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a communication network system in local 5G. [Background technology]

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

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-87683 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides an improved DAS. [Means for solving the problem]

[0005] One aspect of the present disclosure provides a distributed antenna system having an indoor wireless device that houses antennas for transmitting and receiving 4G and 5G wireless communication waves in a single housing. [Effects of the Invention]

[0006] According to the present invention, an improved DAS is provided. [Brief explanation of the drawings]

[0007] [Figure 1] An overview of DAS is shown below. [Figure 2] FIG. 1 is a diagram illustrating the configuration of a local 5G network according to related technology. [Figure 3] FIG. 1 is a diagram illustrating the configuration of a communication network according to a first embodiment. [Figure 4] FIG. 1 is a diagram illustrating an example of an inter-base communication system according to a first embodiment. [Figure 5] FIG. 10 is a diagram showing another example of an inter-site communication system. [Figure 6] FIG. 10 is a diagram showing an overview of a communication system 2 according to a second embodiment. [Figure 7] FIG. 2 is a diagram illustrating an example of the functional configuration of a communication system 2. [Figure 8] DAS device overview. [Figure 9] Front view of master unit MU [Figure 10] Rear view of master unit MU [Figure 11] Four-sided view of base station RU [Figure 12] Front view of base station RU [Figure 13] An enlarged view of the interface section of the base station RU. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1. Overview The development of a communication system known as 5G (fifth generation mobile communication system) has made communication increasingly important. When a new communication system is developed, in order to introduce this communication system at bases such as office buildings, hotels, and factories, it is necessary to install equipment compatible with the new communication system. However, installing such equipment often imposes a significant burden on the base managers (e.g., office building owners) or users (e.g., office building tenants).

[0009] For example, in 5G, companies or local governments may individually develop their own 5G networks (so-called road networks). It is permitted to build, operate, and use a 5G network (national 5G). The core network servers required to operate a 5G network are expensive, and building and operating one can be very costly.

[0010] Alternatively, there may be a demand to install a local 5G network within a building to provide 5G wireless access. In this case, for example, if four telecommunications carriers are providing 5G services, a local 5G network must be installed within the building for each of the four carriers. Furthermore, there is a demand to install not only a 5G network within the building, but also a wireless LAN such as Wi-Fi. To meet this demand, a Wi-Fi network must be installed within the building in addition to the 5G network, which places a significant burden on the building owner.

[0011] A distributed antenna system (DAS) is a system that connects multiple small antennas to a central base station or network to improve wireless signal coverage in locations where wireless signals from a base station are difficult to reach, such as inside a building. DAS systems are sometimes required to support 4G (LTE) and 5G, but in related technologies, 4G and 5G systems are provided separately. For example, in local 5G, radio units (RUs) (hereafter referred to as base station RUs) are provided in separate housings: one for 4G and one for 5G. There are several reasons for this. One is that 4G uses a wide frequency band, from 700 MHz to 3.4 GHz, and integrating it with a 5G system in a single housing results in high power consumption. However, adding more housings requires more installation space, which in turn increases costs.

[0012] Figure 1 shows an overview of DAS. The assets from the base station to the mobile carrier radio equipment belong to each mobile carrier (also known as a carrier). These are installed by each carrier. For example, if there are four carriers, each of these companies will install the equipment. The MU (master unit) is the DAS's signal processing device, and receives signals from outside and distributes 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 came up with the idea of ​​a configuration in which the DAS (specifically, the base station RU) does not transmit and receive radio waves (wireless communication waves) in all 4G and 5G frequency bands, but transmits and receives radio waves in only specific limited frequency bands. In this embodiment, the frequency bands supported by the DAS are, for example, only the following three frequency bands, and no other frequency bands are supported. 4G: 1.7GHz band (FDD) 4G: 2.1GHz band (FDD) 5G: 3.6-4.0GHz band (TDD)

[0014] In terms of 5G communications, when frequency bands are classified into low band (Sub-1 GHz band: 600 MHz to 1 GHz), mid band (Sub-6 GHz band: 1 GHz to 6 GHz), and high band (millimeter wave band: 24 GHz to 100 GHz), this means that only a portion of the mid-band frequency band is supported. This is based on the idea that low-band radio waves are excluded from the support range of base station RUs because there is a higher chance that radio waves from outdoors will reach indoors even without using the indoor base station RU than mid-band abnormal radio waves. The same applies to 4G communications.

[0015] 2. First embodiment FIG. 2 is a diagram illustrating the configuration of a local 5G network according to related technology. The local 5G network has a base station RU, a router RT, and a core network server 5GC at each base station. This configuration has the problem of high initial implementation costs and the need for advanced operational technology. In particular, the implementation of a core network server 5GC can cost tens of millions of yen, which is a major obstacle for companies or organizations seeking to implement it.

[0016] FIG. 3 is a diagram illustrating a configuration of a communication network according to the first embodiment. 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 cost of introducing the local 5G network can be reduced.

[0017] FIG. 4 is a diagram illustrating an example of an inter-site communication system according to the first embodiment. Consider communication between two sites, site A and site B. Sites A and B each include 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, the remote station / aggregation base station CU / DU, and the router RT at each site are examples of communication equipment installed at that site.

[0018] Router RT[A] and router RT[B] are connected via SD-WAN. In other words, slice A[1] and slice B[1] are connected via SD-WAN. With this configuration, all communications between bases are logically independent from other networks. This makes it possible to form a secure and high-speed communications network between base A and base B. Note that the private network connecting router RT[A] and router RT[B] is not limited to SD-WAN. The private network connecting router RT[A] and router RT[B] may be another private network, such as a dedicated line, wide area Ethernet, or IP-VPN (Virtual Private Network).

[0019] At least one of the routers RT[A] and RT[B] may be connected to a DN (Data Network) such as the Internet by a UPF (User Plane Function). Communication between a terminal and a DN at a point uses a different slice from communication between bases, so it does not affect communication between bases.

[0020] A core network server 5GC implemented on the cloud is connected to this SD-WAN. The core network server 5GC controls the remote stations / aggregation base stations CU / DU for each of bases A and B.

[0021] FIG. 5 is a diagram showing another example of a site-to-site communication system. Sites A and B each have a base station RU and a router RT. In contrast to the example in FIG. 4, this system differs in that the remote stations / aggregation base stations CU / DU are implemented on the cloud, and there are no remote stations / aggregation base stations 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 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].

[0022] Router RT[A] and Router RT[B] are connected via SD-WAN. In other words, slice A[1] and slice B[1] are connected via SD-WAN. With this configuration, all communications between bases are logically independent from other networks. This allows a secure and high-speed communications network to be formed between base A and base B.

[0023] This SD-WAN is connected to remote stations / aggregation base stations CU / DU implemented on the cloud. In addition, 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]. In addition, a UPF may be implemented on the cloud, and a slice other than the one used for communication between base stations may be connected to a DU such as the Internet.

[0024] In the examples of Figures 4 and 5, a terminal UE [A] at site A and a terminal UE [B] at site B can communicate securely using a local 5G network slice while satisfying the requirements (or settings) according to the application. Slice A [1] and slice B [1] between the terminal UE [A] and the 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 an event in which the router RT [A] accepts an access request from the terminal UE [A] to the terminal UE [B]. When the router RT [A] accepts the access request from the terminal UE [A] to the terminal UE [B], the core network server 5GC reads out slice settings related to communication between the terminal UE [A] and the terminal UE [B] from a database stored in a storage means. The core network server 5GC controls the router RT [A] and the router RT [B] to generate slices according to the settings. Router RT[A] and router RT[B] generate slices A[1] and B[1] according to instructions from the core network server 5GC. When 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].

[0025] As described above, according to this embodiment, by connecting bases via an SD-WAN private network, it is possible to provide secure, flexible, and easy-to-operate intra- and inter-base communication services. For example, if base A is a local private hospital and base B is a university hospital, a doctor at base A can make a diagnosis while checking in real time the results of an examination (e.g., images from an imaging diagnosis) using an examination device that is only available at base B.

[0026] 3. Second embodiment Fig. 6 is a diagram showing an overview of a communication system 2 according to a second embodiment. The communication system 2 reduces the cost of implementation by sharing a physical line laid within a base with networks that have different standards or providers. The second embodiment relates to so-called infrastructure sharing.

[0027] The communication system 2 can be considered as an example of a communication network within a base station in the communication network of Fig. 3. First, the configuration related to 5G communication will be described. The communication system 2 includes a base station, an optical concentrator, a repeater, a splitter, and a slave station. These are installed within the base station (for example, within a building or on a premises).

[0028] 5G carrier radio equipment is a device that transmits and receives radio signals for each carrier. The base side of the carrier radio equipment is connected to a parent device, and the outside is connected to the telecommunications company's station building. Communication system 2 communicates with external 5G networks via the carrier radio equipment. The communication path within the base is mainly optical fiber (i.e., optical fiber; an example of a physical line). The base is divided into multiple areas (e.g., multiple floors). Optical fiber lines are laid in each area via repeaters. A terminal is connected to the end of the optical fiber line. A 5G antenna is connected to the terminal. The 5G antenna forms a 5G access area within the base (i.e., within the building).

[0029] The parent device is connected to 5G carrier radio equipment from multiple carriers (Companies A, B, and C in the figure). However, instead of each carrier laying its own optical fiber line, a set of optical fiber lines laid within a base station is shared by multiple carriers. The parent device and the child device are physically connected by a common line, but are logically divided into multiple logical networks. Signals from multiple carriers are transmitted physically along the same path, but logically along separate paths. Network slices in 5G communications are used as logical networks. In this example, the logical network includes three slices: slice S[A] transmitting Company A's signal, slice S[B] transmitting Company B's signal, and slice S[C] transmitting Company C's signal. The child device outputs signals received from the optical fiber line to a 5G antenna. The 5G antenna is shared by multiple carriers. Alternatively, a dedicated 5G antenna for each carrier may be used.

[0030] This is true not only for the downlink but also for the uplink. The 5G antenna outputs signals received from the terminal to the slave device. The slave device outputs company A's wireless signal to slice S[A], company B's wireless signal to slice S[B], and company C's wireless signal to slice S[C]. These signals are physically transmitted over a common optical line. The master device outputs signals received over the optical line to the 5G carrier radio device. The master device outputs signals transmitted via slice S[A] to the 5G carrier A radio device, signals transmitted via slice S[B] to the 5G carrier B radio device, and signals transmitted via slice S[C] to the 5G carrier C radio device. Each 5G carrier radio device outputs signals to its own network.

[0031] Next, the configuration related to the wireless LAN will be explained. An optical concentrator is installed downstream of the base station from the parent device. When viewed 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 parent device and signals from an external network (the Internet or a closed network) are input to the optical concentrator via optical lines. 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 communications. In this example, the parent device and optical concentrator are devices housed in a single housing.

[0032] A splitter is installed in part of the optical line. A splitter is a device that splits a signal transmitted over an optical line into multiple optical lines. The splitter is installed, for example, between a repeater and a slave unit. The output of the splitter is branched into an output for 5G communication as well as an output for wireless LAN communication. An optical terminal device (e.g., ONU, Optical Network Unit) is connected to the optical line output for wireless LAN communication. A WiFi antenna is connected to the optical terminal device. A slice S[D] is formed between the optical concentrator and the optical terminal device. The wireless LAN signal is transmitted via the slice S[D].

[0033] Next, the configuration for local 5G will be explained. The output of the splitter is branched into an output for 5G communication, an output for WLAN communication, and an output for local 5G. The CU, DU, and RU are connected to the optical line for the local 5G output. A slice S[E] is formed between the optical concentrator and the RU. Local 5G signals are transmitted via the slice S[E]. The communication equipment described above is installed within the base.

[0034] The network configuration within the base illustrated in Fig. 4 of the first embodiment corresponds to the configuration obtained by omitting the configuration related to 5G communication and the configuration related to wireless LAN in the example of Fig. 6. That is, Fig. 4 shows an example in which a network slice formed within base A and a network slice formed within base B are connected by a closed logical network.

[0035] The communication system 2 is connected to the core network server 5GC via the Internet or a closed network (more specifically, an SD-WAN closed network). The core network server 5GC controls the generation of network slices for the communication system 2 and communication via the network slices. The core network server 5GC is provided by a business operator that provides a communication environment within a base. This business operator may be a different business operator from the business operator that provides 5G communication.

[0036] FIG. 7 is a diagram illustrating an example of the functional configuration of the 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. The NSSF (Network Slice Selection Function) selects the SMF for each slice. The AUSF (Authentication Server Function) authenticates subscribers (i.e., is an authentication server). The UDM (Unified Data Management) stores subscriber-related information. The UDR (Unified Data Repository) maintains the subscriber status. The AMF (Access and Mobility Management Function) performs subscriber authentication, security, and terminal location management. The SMF (Session Management Function) performs session management. SMF is an example of a storage means for storing information related to a logical network using communication equipment and physical lines installed in a base, and a control means for controlling the communication equipment so that terminals connected to the communication equipment at the base communicate via the logical network using the information stored in the storage means. NRF (Network Repository Function) provides services for each network function. The UPF (User Plane Function) transfers user data packets. In this example, three UPFs, UPF-1, UPF-2, and UPF-3, are shown. Although not shown, the core network server 5GC further includes a Network Exposure Function (NEF). The NEF detects user movement and controls communications, for example. The core network server 5GC provides a control NF for this purpose to the outside via an API. These are the functions of the core network server 5GC. The core network server 5GC of the first embodiment also has a similar functional configuration. The first embodiment and the second embodiment are common in that the communication network of the base is controlled via multiple network slicings (logical networks). Note that in the first embodiment, communication within each base may be divided into multiple network slices.

[0037] This diagram shows three logical paths corresponding to three communication standards. The first logical path is a logical path for 5G communication, indicated as slice A in the diagram. The example in Figure 6 shows an example in which this logical path is divided into three network slices according to the number of communication carriers. The second logical path is a logical path for wireless LAN, indicated as slice B in the diagram. The third logical path is a logical path for local 5G, indicated as slice C in the diagram.

[0038] The AMF controls the AGF / FMIF / FRG for 5G communication, the N3IWF for wireless LAN, and the gNB for local 5G. The SMF controls the UPF-1 for 5G communication, the UPF-2 for wireless LAN, and the UPF-3 for local 5G. In this example, the N3IWF is implemented in the SD-WAN router. In other words, the branch communication equipment includes an SD-WAN router with the N3IWF implemented.

[0039] Here, an example has been described in which the communication system 2 supports three communication standards: 5G communication, wireless LAN, and local 5G. However, the communication standards supported by the 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. The number of communication standards supported by the communication system 2 may be one, two, four or more. The communication standards supported by the communication system 2 themselves are one. A single network slice may support multiple carriers. That is, multiple network slices may correspond to multiple carriers. The number of coexisting network slices may be increased as much as allowed by the standard.

[0040] According to this example, the person who develops the communication environment at a base (e.g., the building owner) can install an optical fiber line within the base and then split the optical fiber line into multiple logical networks to support multiple communication standards or carriers. Even if a new communication standard emerges in the future, it will be possible to support the new communication by connecting a device that supports the new communication standard downstream of the splitter in the example of Figure 6 and setting up an additional network slice for communication of that communication standard.

[0041] The core network server 5GC is a server implemented or installed in the cloud. The core network server 5GC may be physically configured as a single device. If a new standard such as 6G emerges in the future, the name "5G core network server" may be changed. In that case, the function corresponding to the 5G core network server in the new standard corresponds to the 5G core network server of the present invention.

[0042] As communications capacity increases, the physical capacity (volume) of the physical lines that transmit communications has become an issue. For example, if an attempt is made to realize a 100 GB communications environment, the volume of the cable would be too large to physically run through piping if an Ethernet cable were used. This necessitates the installation of optical fiber lines within the base station, but installing a dedicated optical fiber line for each communications standard or each communications carrier imposes a large cost burden on the installer. According to this embodiment, the physical line can be shared by multiple communications standards or communications carriers, making it easier to implement a communications environment within the base station.

[0043] 4. Coexistence of 4G and 5G Figure 8 shows a schematic diagram of the DAS equipment. It shows the master unit (MU), hub unit (HU), and base station RU. Figure 9 shows a front view of the master unit MU, and Figure 10 shows a rear view of the master unit MU. Figure 11 shows a four-sided view of the base station RU, and Figure 12 shows a front view of the base station RU. Figure 13 shows an enlarged view of the interface section of the base station RU.

[0044] The base station RU has a so-called 2T2R antenna common to the 1.7 GHz band and 2.1 GHz band, and a 4T4R antenna for the 3.7 GHz band (3.6 to 4.0 GHz band).

[0045] 5. Other Embodiments The present invention is not limited to the above-described embodiment, and various modifications are possible. Some modifications will be described below. Two or more of the features described in the following modifications may be used in combination.

[0046] The combination of frequency bands supported by the base station RU is not limited to those exemplified in the embodiments. Any combination may be used as long as it includes at least one frequency band from 4G and at least one frequency band from 5G. From the viewpoint of device configuration, it is preferable to implement both 4G and 5G by selecting one or two frequency bands from the frequency bands belonging to the medium band.

[0047] The types of physical lines are not limited to those exemplified in the embodiments, and a coaxial cable may be used instead of an optical line, or vice versa.

[0048] The functions of the core network server 5GC described in the embodiment (FIG. 7) are merely examples. Some of the functions shown in the figures may be omitted, and other functions may be added.

[0049] One aspect of the present disclosure provides a communication network system having a first local 5G base station installed at a first location, a first router installed at the first location 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 location different from the first location, a second router installed at the second location 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 a cloud and controlling the first aggregation base station and the second aggregation base station, a plurality of slices included in a physical network from the first local 5G base station to the first router, including a first slice, a plurality of slices included in a physical network from the second local 5G base station to the second router, including a second slice, and a closed network connected to the first router and the second router, connecting the first slice and the second slice.

[0050] 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.

[0051] The first remote station, the first aggregation base station, the second remote station, and the second aggregation base station may be located in the cloud.

[0052] The private network may be an SD-WAN private network.

[0053] 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.

[0054] The 5G core network server may have a database that records information regarding the terminal at the first location, the terminal at the second location, and slice settings when communication occurs between the terminal at the first location and the terminal at the second location, and when the specified event occurs, the 5G core network server may refer to the database and control the first router and the second router to generate the first slice and the second slice based on the settings. [Explanation of symbols]

[0055] RU: base station, CU / DU: remote station / aggregation base station, RT: router, 5GC: core network server

Claims

[Claim 1] A distributed antenna system with an indoor wireless device that houses antennas for transmitting and receiving 4G and 5G wireless communication waves in a single housing.

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