Antenna Distribution System

Abstract

We provide an antenna distribution system that enables the introduction of 5G networks indoors in facilities and increases capacity without incurring time or cost. [Solution] An antenna distribution system comprising one or more baseband devices, one or more remote radio devices each connected to the one or more baseband devices, a master unit connected to the one or more remote radio devices via a coaxial cable, one or more slave units connected to the master unit, and one or more antennas each connected to a coaxial cable branched by one or more distributors from a coaxial cable connected to each of the one or more slave units.

Description

[Technical Field]

[0001] The present invention relates to an antenna distribution system, and more particularly to an antenna distribution system for use in wireless communication services provided indoors at a facility. [Background technology]

[0002] Wireless relay systems, which are used to extend the wireless communication area of ​​base stations in mobile communication systems, vary in frequency coverage, monthly costs, etc. depending on the configuration. Configurations using coaxial cable are the cheapest in terms of both installation and maintenance costs, and are the most commonly used configurations for providing 4G (4th Generation) networks.

[0003] Wireless relay systems used indoors in facilities can be divided into those used for services provided individually by each telecommunications carrier and those used for services jointly provided by multiple telecommunications carriers. Services provided individually by each telecommunications carrier include those using coaxial cables, distributed antenna systems (DAS), radio dot systems, etc. DAS systems and radio dot systems use composite cables instead of coaxial cables (see, for example, Patent Document 1 and Patent Document 2). Services jointly provided by multiple telecommunications carriers also include those using coaxial cables (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7419116 specification [Patent Document 2] Japanese Patent Application Laid-Open No. 2024-44504 [Patent Document 3] Japanese Patent Publication No. 2022-185171 Summary of the Invention [Problem to be solved by the invention]

[0005] When trying to increase capacity by introducing a 5G (5th Generation) network into an existing configuration that provides a 4G network, the configurations that can introduce the 5G network include a DAS system and a coaxial cable configuration for services provided individually by each telecommunications carrier. Introducing a 5G network into a configuration that provides a 4G network using coaxial cable requires building a separate configuration from the 4G network, and all existing coaxial cables must be replaced with composite cables, which is extremely time-consuming and costly. Introducing a 5G network into a DAS system also requires an increase in the number of devices, which is costly. Introducing a 5G network into a service jointly provided by multiple telecommunications carriers also requires the installation of additional systems compatible with the 5G network, which is time-consuming and costly.

[0006] The present invention has been made in consideration of the above points, and aims to provide an antenna distribution system that enables the introduction of a 5G network inside a facility without incurring time or cost, and increases the amount of data that can be communicated. [Means for solving the problem]

[0007] A first aspect of the present invention is an antenna distribution system comprising one or more baseband devices, one or more remote radio devices each connected to the one or more baseband devices, a master unit connected to the one or more remote radio devices via a coaxial cable, one or more slave units connected to the master unit, and one or more antennas each connected to a coaxial cable branched by one or more distributors from a coaxial cable connected to each of the one or more slave units.

[0008] In the first aspect of the present invention, the one or more slave units may have an output of 1 W or more for a bandwidth of 20 MHz per coaxial cable connected to each of the one or more slave units.

[0009] In the first aspect of the present invention, the difference in the length of the coaxial cables between the slave unit and each of the multiple antennas does not need to exceed the distance at which a delay difference occurs due to the multiple signals output by one or more baseband devices.

[0010] In the first aspect of the present invention, the difference between the lengths of the coaxial cables between the slave unit and each of the plurality of antennas may be less than 564 m.

[0011] The first aspect of the present invention may further comprise a digital filter that removes intermodulation signals that occur due to the superposition of signals having a plurality of frequencies that propagate within the coaxial cable.

[0012] In the first aspect of the present invention, communication between the master unit and one or more slave units may be optical communication. [Effects of the Invention]

[0013] According to the present invention, it is possible to introduce a 5G network inside a facility without spending time and money, to increase capacity, and to provide an antenna distribution system that can also accommodate sharing measures. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram illustrating an overview of an antenna distribution system according to an embodiment of the present invention. [Figure 2] These figures show an example of the configuration of a conventional wireless relay system. Figure 2(a) shows a wireless relay system using coaxial cables, Figure 2(b) shows an antenna distribution system (optical DAS), and Figure 2(c) shows a Radio Dot System configuration. [Figure 3] This is an example of the configuration of a conventional wireless relay sharing system before the introduction of 5G networks and increased capacity. [Figure 4] This is an example of the configuration of a conventional wireless relay sharing system after the introduction of 5G networks and increased capacity. DETAILED DESCRIPTION OF THE INVENTION

[0015] Next, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings relating to the embodiment, the same or similar parts are designated by the same or similar reference numerals. Of course, there are also parts whose relationships differ between the drawings.

[0016] Furthermore, the embodiments are merely examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the configuration of each component to those described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims.

[0017] (Embodiment) An overview of an antenna distribution system 10 according to this embodiment will be described with reference to Fig. 1. The antenna distribution system 10 according to this embodiment is a wireless relay system provided individually by each telecommunications carrier to extend the wireless communication area of ​​a base station of a mobile communication system indoors in a facility.

[0018] The antenna distribution system 10 according to this embodiment can be applied to facilities where a large number of users are concentrated and where a large capacity of data communication is required, such as inside a facility, an event facility such as a stadium, a public facility such as a library or an art museum, a sports facility, a commercial facility, a station, or a university.

[0019] As shown in FIG. 1, an antenna distribution system 10 according to this embodiment includes one or more baseband units (Base Band Units, BBUs) 101a, 101b, and 101c, one or more remote radio units (Remote Radio Units, RRUs) 102a, 102b, 102c, and 102d connected to the one or more baseband units 101a, 101b, and 101c, respectively, a master unit (Master Unit, MU) 103 connected to the one or more remote radio units 102a, 102b, 102c, and 102d, one or more remote units (Remote Units, RUs) 104a and 104b connected to the master unit 103, and one or more antennas 105a to 105h connected to the one or more remote units 104a and 104b via coaxial cables.

[0020] One or more baseband devices 101a, 101b, 101c may be connected to one or more remote radio devices 102a, 102b, 102c, 102d by an optical fiber 106. One or more remote radio devices 102a, 102b, 102c, 102d may be connected to the master device 103 by a coaxial cable 107. The master device 103 may be connected to one or more slave devices 104a, 104b by an optical fiber 108.

[0021] One or more slave units 104a, 104b are connected to one coaxial cable 109a, 109b, respectively, and one or more antennas 105a-105h are connected to the coaxial cables 109a, 109b via distributors 110a-110f and coaxial cables 109c, 109d, respectively. In the antenna distribution system 10 according to this embodiment, the distributors 110a-110f are couplers (CUPs) as an example, but are not limited to this. The slave units of this application may be high-output slave units having an output of 1 W or more per connected coaxial cable in a 20 MHz bandwidth.

[0022] 1, the antenna distribution system 10 according to the present embodiment is configured as a SIMO configuration in which one or more coaxial cables 109a, 109b are connected to each of one or more slave units 104a, 104b, and one or more antennas 105a, 105h are connected to each of the coaxial cables 109c, 109d via distributors 110a, 110f, respectively. However, the antenna distribution system 10 according to the present embodiment may be configured as a MIMO configuration in which multiple coaxial cables are connected to each of one or more slave units, and one or more antennas are connected to each of the multiple coaxial cables connected to each of the one or more slave units via a distributor. In the antenna distribution system 10 according to the present embodiment, even if the base station of a mobile communication system installed indoors in a facility is configured as a SIMO configuration, if higher speed is required, the speed can be increased by changing to a MIMO configuration by increasing the number of coaxial cables connected to each of the one or more slave units.

[0023] One or more baseband devices 101a, 101b, 101c are connected to an external network (not shown) and perform packet transfer as well as management such as control and authentication.

[0024] One or more remote radio devices 102a, 102b, 102c, and 102d convert optical signals received from one or more baseband devices 101a, 101b, and 101c into radio signals and output them to the parent device 103, and convert radio signals received from the parent device 103 into optical signals and output them to one or more baseband devices 101a, 101b, and 101c.

[0025] The master device 103 converts radio signals received from one or more remote radio devices 102a, 102b, 102c, and 102d into optical signals and outputs them to one or more slave devices 104a and 104b, and converts optical signals received from one or more slave devices 104a and 104b into radio signals and outputs them to one or more remote radio devices 102a, 102b, 102c, and 102d.

[0026] One or more slave units 104a, 104b convert optical signals received from the master unit 103 into wireless signals and output them to one or more antennas 105a to 105h via distributors 110a to 110f, and convert wireless signals received from one or more antennas 105a to 105h via distributors 110a to 110f into optical signals and output them to the master unit 103.

[0027] The one or more antennas 105a to 105h radiate radio signals received from one or more slave devices 104a, 104b via distributors 110a to 110f into the atmosphere as radio waves, and transmit radio signals received from one or more user terminals to one or more slave devices 104a, 104b via distributors 110a to 110f. The radiated radio signals are received by one or more user terminals (not shown).

[0028] 2 shows the configurations of a wireless system 21 using a conventional coaxial cable, a distributed antenna system (optical DAS) 22, and a Radio Dot System 23, all of which are shown for comparison with the distributed antenna system 10 according to this embodiment. Here, DAS stands for Distributed Antenna System, and a configuration in which multiple antennas are branched is called a DAS. A DAS that uses an optical repeater, such as the distributed antenna system (optical DAS) 22, is called an optical DAS. The Radio Dot System 23 is a system developed by Ericsson, and has a simpler structure than the distributed antenna system (optical DAS) 22. Both the distributed antenna system (optical DAS) 22 and the Radio Dot System 23 use composite cables.

[0029] 2(a) is configured with a baseband device 211, one or more remote radio devices 212, and one or more antennas 213a to 213h connected to the one or more remote radio devices 212 via distributors 216a to 216f. The baseband device 211 and the remote radio devices 212 are connected by an optical cable 214. The remote radio devices 212 and the multiple antennas 213 are connected by a coaxial cable 215.

[0030] The antenna distribution system (optical DAS) 22 shown in FIG. 2(b) is composed of one or more baseband devices 221, one or more remote radio units (RRUs) 222, a master unit 223, one or more hub units (HUs) 224, one or more slave units 225, and one or more antennas 226. The one or more baseband devices 221 and the one or more remote radio units 222 are connected by an optical cable 227. The one or more remote radio units 222 and the master unit 223 are connected by a coaxial cable 228. The master unit 223 and the one or more hub units 224 are connected by an optical cable 229. The hub unit 224 and the multiple slave units 225 are connected by a composite cable 2210. One or more antennas can be connected to one slave device, but in the antenna distribution system (optical DAS) 22 shown in Fig. 2(b), one antenna is connected to one slave device, as an example. A hub device 224 is connected with a number of composite cables 2210 equal to the number of slave devices 225 connected to the hub device 224.

[0031] The Radio Dot System 23 shown in FIG. 2(c) is composed of one or more baseband devices 231, multiple indoor radio devices (Indoor Radio Units, IRUs) 232, and one or more antennas 234 via one or more slave devices 233. The one or more baseband devices 231 and the multiple indoor radio devices 232 are connected by an optical cable 235. The multiple indoor radio devices 232, the one or more slave devices 233, and the one or more antennas 234 are connected by a composite cable 236. One antenna 234 is connected to the slave device 233. To each of the multiple indoor radio devices 232, the same number of composite cables 236 as the number of the one or more slave devices 233 connected to the multiple indoor radio devices 232 are connected.

[0032] Conventional wireless systems 21 using coaxial cables are inexpensive in terms of equipment costs, construction costs, and operating costs such as electricity charges, while wireless relay systems using antenna distribution systems 22 and radio dot systems 23 are more expensive than systems using coaxial cables. Among the wireless relay systems already in use indoors at facilities, systems using coaxial cables are the most commonly used. For wireless relay systems to be newly installed indoors at facilities, systems using coaxial cables are also the most commonly selected.

[0033] In an indoor facility currently providing a 4G network using a conventional system—either a coaxial cable-based wireless system 21, an antenna distribution system (optical DAS) 22, or a Radio Dot System 23—if a 5G network is introduced to increase capacity, the configuration shown in FIG. 2(a) for the wireless system 21 cannot introduce or increase the capacity of the 5G network, and the coaxial cable-based wireless system 21 must be changed to either the antenna distribution system (optical DAS) 22 or the Radio Dot System 23. Changing the coaxial cable-based wireless system 21 to either the antenna distribution system (optical DAS) 22 or the Radio Dot System 23 requires the removal of the coaxial cable and the laying of a new composite cable. Furthermore, introducing a 5G network to either the antenna distribution system (optical DAS) 22 or the Radio Dot System 23 requires the addition of a baseband device or a remote wireless device.

[0034] 2(b), composite cables 2210 are connected to the hub device 224 of the antenna distribution system (optical DAS) 22, and the number of composite cables 2210 is equal to the number of multiple slave devices 225 connected to the hub device 224. Furthermore, composite cables 236 are connected to each of the multiple indoor wireless devices 232 of the Radio Dot System 23, and the number of composite cables 236 is equal to the number of one or multiple slave devices 233 connected to the multiple indoor wireless devices 232. When changing the wireless system 21 using coaxial cables to either the antenna distribution system (optical DAS) 22 or the Radio Dot System 23, or when adding a slave device 225 or a slave device 233, the number of hub devices 224, slave devices 225, IRUs 232, slave devices 233, etc. increases, and costs for equipment, construction, electricity, and other operating costs rise.

[0035] According to the antenna distribution system 10 of this embodiment shown in Figure 1, it is possible to introduce a 5G network and increase its capacity by simply adding a parent device 103 and one or more child devices 104a, 104b connected to the parent device 103 to the wireless system 21 using a coaxial cable shown in Figure 2(a).

[0036] The one or more baseband devices may output signals at at least one of the following frequencies: 900 MHz, 1.5 GHz, 1.7 GHz, 2.1 GHz, 2.5 GHz, 3.4 GHz, 3.5 GHz, and 3.9 GHz. The bandwidths of the signals at these frequencies that the one or more baseband devices can output are 10 MHz, 15 MHz, 15 MHz, 20 MHz, 20 MHz, 40 MHz, 40 MHz, and 100 MHz, respectively. Supporting signals with a wide frequency bandwidth of 40 MHz or more enables increased capacity. In other words, in a 5G network, increased capacity can be supported using baseband devices with the same configuration as in a 4G network. As a result, increased capacity can be achieved by supporting the frequencies of the output signals of the one or more baseband devices at 3.4 GHz, 3.5 GHz, and 3.9 GHz. The frequency of the signal output by the above-mentioned baseband device is just an example, and in the antenna distribution system 10 of this embodiment, any frequency can be selected that is used for applications such as mobile phones, PHS, and mobile satellite communications, as long as it is a frequency defined as "radio waves" under the Radio Law, i.e., 3,000,000 MHz (=3000 GHz) or less.

[0037] When the frequencies of signals propagating within the coaxial cable used in antenna distribution system 10 according to this embodiment shown in Fig. 1 overlap, a signal containing frequency components not originally included, called intermodulation (IM), is generated. In antenna distribution system 10 according to this embodiment, IM can be removed by using a digital filter that cuts IM.

[0038] 1, one or more slave units 104a, 104b are connected to one coaxial cable 109a, 109b, respectively, and multiple antennas 105a-105h are connected to the coaxial cables 109a, 109b via distributors 110a-110h, respectively. If the difference in length of the coaxial cables between each of the one or more slave units 104a, 104b and each of the multiple antennas 105a-105h exceeds the distance at which a delay difference occurs between multiple signals output by one or more baseband devices, degradation of signal quality occurs.

[0039] For example, the CP (Cyclic Prefix) length for 3.4 GHz and 3.5 GHz is 2.35 μs. The speed of light in a vacuum is 3.0 × 10 8 m / s, the distance in vacuum where the delay difference occurs is 2.35 × (3.0 × 10 8 ) = 705 m. If the wavelength shortening rate of the coaxial cable is 80%, the length of the coaxial cable where the delay difference occurs is 705 × 0.8 = 564 m.

[0040] In antenna distribution system 10 according to this embodiment shown in Fig. 1, when one or more baseband devices output signals of frequencies of 3.4 GHz and 3.5 GHz, no delay difference occurs unless the difference in length of the coaxial cable between each of one or more slave devices 104a, 104b and each of the multiple antennas 105a-105h exceeds 564 m. That is, in antenna distribution system 10 according to this embodiment shown in Fig. 1, no delay difference occurs unless the difference in length of the coaxial cable between each of one or more slave devices 104a, 104b and each of the multiple antennas 105a-105h exceeds the distance obtained by multiplying the CP length of the multiple signals propagating inside the coaxial cable by the speed of light inside the coaxial cable.

[0041] (Comparative Example) The antenna distribution system 10 according to the embodiment shown in FIG. 1 can be applied to an antenna distribution system jointly provided by multiple telecommunications carriers when expanding the wireless communication coverage area of ​​a base station of a mobile communication system indoors in a facility.

[0042] For comparison with the antenna distribution system 10 according to the embodiment shown in Figure 1, Figure 3 shows the configuration of a conventional wireless relay sharing system jointly provided by multiple telecommunications carriers before the introduction of 5G networks and increased capacity, and Figure 4 shows the configuration after the introduction of 5G networks and increased capacity.

[0043] 3 includes a baseband device 301, one or more remote radio devices 302a and 302b connected to the baseband device 301 via an optical cable 306, a master device 303 connected to the one or more remote radio devices 302a and 302b via a coaxial cable 307, one or more slave devices 304a and 304b connected to the master device 303, and multiple antennas 305a to 305f connected to the one or more slave devices 304a and 304b via distributors 310a to 310f via coaxial cable 309. As an example, the sharing system 30 shown in FIG. 3 is configured such that a specific operator provides the baseband device 301 and one or more remote radio devices 302a and 302b connected to the baseband device 301, and multiple operators share the master device 303 and one or more slave devices 304a and 304b connected to the master device 303.

[0044] Since the sharing system 30 is operated jointly by multiple businesses, it can be operated at low cost for individual businesses. However, since it is not possible to introduce a 5G network or increase the capacity of the sharing system 30 itself, when introducing a 5G network or increasing the capacity of the sharing system 30, it is necessary to introduce a sharing system 40 compatible with the 5G network in addition to the sharing system 30, as shown in Figure 4.

[0045] The sharing system 40 shown in FIG. 4 includes a baseband device 401, a remote radio device 402 connected to the baseband device 401 via an optical cable 408, a master device 403 connected to the remote radio device 402 via a coaxial cable 409, a hub device 404 connected to the master device 403 via an optical cable 410, and multiple antennas 406 connected to the hub device 404 via a composite cable 411 via one or more slave devices 405. Similar to the hub device 224 of the antenna distribution system (optical DAS) 22 and the multiple indoor radio devices 232 of the Radio Dot System 23 shown in FIG. 2, the hub device 404 is connected to numerous composite cables 411, which requires significant installation costs. As a result, even in the case of joint operation by multiple operators, the introduction and increased capacity of a 5G network requires significant installation costs.

[0046] Comparing the sharing system 30 shown in Fig. 3 with the antenna distribution system 10 according to the first embodiment shown in Fig. 1, the antenna distribution system 10 has a configuration in which the baseband device 301 and one or more remote radio devices 302a and 302b of the sharing system 30 shown in Fig. 3 are replaced with one or more baseband devices 101a, 101b, and 101c and one or more remote radio devices 102a, 102b, 102c, and 102d shown in Fig. 1. By applying the antenna distribution system according to this embodiment to a wireless relay system jointly provided by multiple telecommunications carriers, it is possible to introduce a 5G network inside a facility without incurring time and cost, and to provide an antenna distribution system capable of increasing capacity.

[0047] As mentioned above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention-specifying matters according to the scope of the claims that are appropriate from the above description.

[0048] The present invention aims to provide an antenna distribution system that enables the introduction of 5G networks indoors and increases capacity without incurring time or cost. In recent years, there has been a demand for the introduction and increase in capacity of 5G networks not only outdoors but also indoors. By using this invention, this can be achieved in a short time and at low cost, which can contribute to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization, and promote innovation and resilience." [Explanation of symbols]

[0049] 10 Antenna Distribution System 101a, 101b, 101c, 211, 221, 231, 301, 401 Base Band Unit (BBD) 102a, 102b, 102c, 102d, 212, 402, 222, 302a, 302b Remote Radio Unit (RRU) 103, 223, 303, 403 Master Unit (MU) 104a, 104b, 225, 233, 304a, 304b, 404a, 404b Remote Unit (RU) 105a~105h, 213a~213h, 226, 234, 305a~305f, 405a~405f Antennas 106, 108 Optical fiber 107, 109a, 109b, 109c, 109d, 215, 228 Coaxial cable 110a~110f, 216a~216f distributor 21 Radio Systems 22 Antenna Distribution System (Optical DAS) 23 Radio Dot System 214, 227, 229, 235 Optical Cable 224 Hub Unit (HU) 2210, 236 composite cable 224 Hub Device 232 Multiple Indoor Radio Units (IRUs) 30, 40 Sharing System

Claims

1. one or more baseband devices; one or more remote radio devices each connected to one or more of said baseband devices; a master unit connected to one or more of the remote radio devices by a coaxial cable; one or more slave devices connected to the master device; One or more antennas connected to coaxial cables branched by one or more distributors from a coaxial cable connected to each of the one or more slave units; An antenna distribution system comprising:

2. The antenna distribution system of claim 1, characterized in that one or more of the sub-units have an output of 1 W or more per coaxial cable connected to each of the one or more sub-units at a bandwidth of 20 MHz.

3. The antenna distribution system of claim 1, characterized in that the difference in coaxial cable length between one or more of the slave units and one or more of the antennas does not exceed the distance at which a delay difference occurs due to the multiple signals output by one or more of the baseband devices.

4. 4. The antenna distribution system according to claim 3, wherein the difference between the lengths of the coaxial cables between one or more of the slave units and one or more of the antennas is less than 564 m.

5. 2. The antenna distribution system according to claim 1, further comprising a digital filter for removing intermodulation signals generated by superposition of signals having a plurality of frequencies propagating through said coaxial cable.

6. 2. The antenna distribution system according to claim 1, wherein communication between said master unit and one or more slave units is optical communication.

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