Distributed antenna system

Abstract

Provided is a distributed antenna system capable of introducing a 5G network into the interior of a facility and increasing capacity without the need to spend time and money. The distributed antenna system comprises: one or a plurality of baseband devices; one or a plurality of remote radio devices respectively connected to the one or plurality of baseband devices; a master unit connected to the one or plurality of remote radio devices using coaxial cables; one or a plurality of slave units connected to the master unit; and one or a plurality of antennas respectively connected to coaxial cables branched by one or a plurality of distributors from coaxial cables respectively connected to the one or plurality of slave units.

Description

Antenna Distribution System

[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.

[0002] Wireless relay systems for extending the wireless communication area of ​​a base station in a mobile communication system vary in supported frequencies, monthly costs, etc., depending on the configuration. Configurations using coaxial cables are the cheapest in both installation and maintenance costs, and are most commonly used in configurations providing 4G (4th Generation) networks.

[0003] Wireless relay systems installed 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), and radio dot systems. 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).

[0004] Patent No. 7419116 JP 2024-44504 ​​A JP 2022-185171 A

[0005] When attempting to increase capacity by introducing a 5G (5th Generation) network into an existing configuration that provides a 4G network, configurations that allow for the introduction of a 5G network include a DAS system and a configuration using coaxial cables for services provided individually by each telecommunications carrier. Introducing a 5G network into a configuration that provides a 4G network using coaxial cables requires the construction of a separate configuration from the 4G network configuration, 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 introduction of an additional system 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 can introduce a 5G network inside a facility without spending time or money, and increase the amount of data that can be communicated.

[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 by 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 a second aspect of the present invention, in the antenna distribution system according to the first aspect of the present invention, one or more slave units may have an output of 1 W or more per coaxial cable connected to each of the one or more slave units over a bandwidth of 20 MHz.

[0009] In a third aspect of the present invention, in an antenna distribution system according to the first or second aspect of the present invention, the difference in the coaxial cable lengths between the slave unit and each of the plurality of antennas does not have to exceed the distance at which a delay difference occurs due to the plurality of signals output by one or more baseband devices.

[0010] In a fourth aspect of the present invention, in an antenna distribution system according to any one of the first to third aspects of the present invention, the difference in the length of the coaxial cables between the slave unit and each of the multiple antennas may be shorter than 564 m.

[0011] In a fifth aspect of the present invention, the antenna distribution system according to any one of the first to fourth aspects of the present invention may further comprise a digital filter that removes intermodulation signals generated by superposition of signals having multiple frequencies propagating within the coaxial cable.

[0012] In a sixth aspect of the present invention, in the antenna distribution system according to any one of the first to fifth aspects of the present invention, communication between the master unit and one or more slave units may be optical communication.

[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.

[0014] 2(a) is a diagram showing an outline of an antenna distribution system according to an embodiment of the present invention; FIG. 2(b) is a diagram showing an example of the configuration of a conventional wireless relay system, where FIG. 2(a) is a wireless relay system using a coaxial cable, FIG. 2(b) is an antenna distribution system (optical DAS), and FIG. 2(c) is a configuration of a Radio Dot System; FIG. 2(c) is an example of the configuration of a conventional wireless relay sharing system before the introduction of a 5G network and increased capacity; FIG. 2(c) is an example of the configuration of a conventional wireless relay sharing system after the introduction of a 5G network and increased capacity.

[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 outline 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 in order to extend the wireless communication coverage 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 amount of data communication capacity 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) 101 a, 101 b, and 101 c, one or more remote radio units (Remote Radio Units, RRUs) 102 a, 102 b, 102 c, and 102 d connected to the one or more baseband units 101 a, 101 b, and 101 c, respectively, a master unit (Master Unit, MU) 103 connected to the one or more remote radio units 102 a, 102 b, 102 c, and 102 d, and one or more slave units (Remote Radio Units, RRUs) connected to the master unit 103. The radio communication system is comprised of two or more radio units (RUs) 104a and 104b, and one or more antennas 105a to 105h connected to one or more slave units 104a and 104b by 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, 105b are connected to the coaxial cables 109a, 109b via distributors 110a, 110f, respectively, via coaxial cables 109c, 109d. In the antenna distribution system 10 according to this embodiment, the distributors 110a, 110b, 110c, 110d are couplers (Couplers, CUPs), as an example, but are not limited thereto. The slave units of this application may be high-output slave units having an output of 1 W or more per connected coaxial cable over 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 coaxial cable 109a, 109b is 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 via coaxial cables 109c, 109d. 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 the mobile communication system installed indoors in the facility is configured as a SIMO configuration, if higher speeds are 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 unit 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 units 104a and 104b, and converts optical signals received from one or more slave units 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, for comparison with the antenna distribution system 10 according to the present 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 also 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 composed of 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 devices (RRUs) 222, a parent device 223, one or more hub devices (Hub Units, HUs) 224, one or more slave devices 225, and one or more antennas 226. The one or more baseband devices 221 and the one or more remote radio devices 222 are connected by an optical cable 227. The one or more remote radio devices 222 and the parent device 223 are connected by a coaxial cable 228. The parent device 223 and the one or more hub devices 224 are connected by an optical cable 229. The hub device 224 and the multiple slave devices 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] The conventional wireless system 21 using coaxial cables is inexpensive in terms of equipment costs, construction costs, and operating costs such as electricity charges, while the wireless relay systems using the antenna distribution system 22 and the Radio Dot System 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 that provides a 4G network using a conventional system, such as a wireless system 21 using a coaxial cable, an antenna distribution system (optical DAS) 22, or a Radio Dot System 23, if a 5G network is introduced to increase the capacity, the configuration shown in FIG. 2(a) of the wireless system 21 does not allow the introduction and increase of the 5G network capacity, and it is necessary to change the wireless system 21 using a coaxial cable to either the antenna distribution system (optical DAS) 22 or the Radio Dot System 23. When changing the wireless system 21 using a coaxial cable to either the antenna distribution system (optical DAS) 22 or the Radio Dot System 23, it is necessary to remove the coaxial cable that was used and lay a new composite cable. Furthermore, when a 5G network is introduced and capacity is increased in either the antenna distribution system (optical DAS) 22 or the Radio Dot System 23, it is necessary to add a baseband device or a remote radio device.

[0034] 2B , 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 slave devices 225 connected to the hub device 224. Furthermore, composite cables 236 are connected to each of the indoor wireless devices 232 of the Radio Dot System 23, and the number of composite cables 236 is equal to the number of slave devices 233 connected to the 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 unit 103 and one or more child units 104a, 104b connected to the parent unit 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 can be output by the one or more baseband devices are 10 MHz, 15 MHz, 15 MHz, 20 MHz, 20 MHz, 40 MHz, 40 MHz, and 100 MHz, respectively. By supporting signals with a wide frequency bandwidth of 40 MHz or more, it is possible to accommodate increased capacity. In other words, in a 5G network, it is possible to accommodate increased capacity using baseband devices with the same configuration as a 4G network. As a result, it is possible to achieve increased capacity 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 (= 3,000 GHz) or less.

[0037] When the frequencies of signals propagating in the coaxial cable used in antenna distribution system 10 according to this embodiment shown in Fig. 1 overlap, a signal having frequency components not originally contained therein, 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. If 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 If the wavelength shortening rate of the coaxial cable is 80%, the length of the coaxial cable where a delay difference occurs is 705 x 0.8 = 564 m.

[0040] In the antenna distribution system 10 according to the present embodiment shown in Figure 1, when one or more baseband devices output signals at frequencies of 3.4 GHz and 3.5 GHz, a delay difference does not occur unless the difference in the length of the coaxial cable between each of one or more slave devices 104a, 104b and each of the multiple antennas 105a to 105h exceeds 564 m. In other words, in the antenna distribution system 10 according to the present embodiment shown in Figure 1, a delay difference does not occur unless the difference in the length of the coaxial cable between each of one or more slave devices 104a, 104b and each of the multiple antennas 105a to 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 Figure 1 can be applied to an antenna distribution system jointly provided by multiple telecommunications carriers when expanding the wireless communication 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] The sharing system 30 shown in Figure 3 is configured to include a baseband device 301, one or more remote radio devices 302a, 302b connected to the baseband device 301 by an optical cable 306, a master device 303 connected to the one or more remote radio devices 302a, 302b by a coaxial cable 307, one or more slave devices 304a, 304b connected to the master device 303, and multiple antennas 305a-305f connected to the one or more slave devices 304a, 304b via distributors 310a-310f by coaxial cable 309. As an example, the sharing system 30 shown in Figure 3 is configured such that a specific operator provides the baseband device 301 and one or more remote radio devices 302a, 302b connected to the baseband device 301, and multiple operators jointly use the master device 303 and one or more slave devices 304a, 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 is composed of a baseband device 401, a remote wireless device 402 connected to the baseband device 401 via an optical cable 408, a parent device 403 connected to the remote wireless device 402 via a coaxial cable 409, a hub device 404 connected to the parent 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 child devices 405. Similar to the hub device 224 of the antenna distribution system (optical DAS) 22 and the multiple indoor wireless devices 232 of the Radio Dot System 23 shown in FIG. 2, the hub device 404 is connected to a large number of composite cables 411, and implementation requires significant costs. As a result, even in joint operation by multiple operators, the implementation and increased capacity of a 5G network requires significant 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 indoors in 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 a 5G network indoors in a facility 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 in facilities. By using the present invention, this can be achieved in a short time and at low cost, and therefore can contribute to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation."

[0049] 10 Antenna distribution system 101a, 101b, 101c, 211, 221, 231, 301, 401 Base band unit (Base Band Unit, BBD) 102a, 102b, 102c, 102d, 212, 402, 222, 302a, 302b Remote radio unit (Remote Radio Unit, RRU) 103, 223, 303, 403 Master unit (Master Unit, MU) 104a, 104b, 225, 233, 304a, 304b, 404a, 404b Remote unit (Remote Unit, RU) 105a to 105h, 213a to 213h, 226, 234, 305a to 305f, 405a to 405f Antennas 106, 108 Optical fibers 107, 109a, 109b, 109c, 109d, 215, 228 Coaxial cables 110a to 110f, 216a to 216f Distributors 21 Wireless systems 22 Antenna distribution systems (optical DAS) 23 Radio Dot Systems 214, 227, 229, 235 Optical cables 224 Hub units (HU) 2210, 236 Composite cables 224 Hub units 232 Multiple indoor radio units (Indoor Radio Units, IRU) 30, 40 Sharing System

Claims

1. An antenna distribution system comprising: one or more baseband devices; one or more remote radio devices each connected to one or more of the baseband devices; a master unit connected to one or more of the 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.

2. The antenna distribution system described in 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. An antenna distribution system as described in claim 1 or 2, characterized in that the difference in the length of the coaxial cables 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. An antenna distribution system as described in any one of claims 1 to 3, characterized in that the difference in the length 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. An antenna distribution system according to any one of claims 1 to 4, further comprising a digital filter for removing intermodulation signals generated by the superposition of signals having multiple frequencies propagating within the coaxial cable.

6. An antenna distribution system according to any one of claims 1 to 5, characterized in that communication between the master unit and one or more slave units is optical communication.

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