Repeater-System

Abstract

Repeater system (10) for forwarding radio signals transmitted during operation in FDD mode, comprising: a donor unit (400) with a first duplexer (444) for converting the frequencies of the radio signals from the transmission frequency to two different intermediate frequencies (IF1, IF2); a service unit (450) with a second duplexer (492) for converting the converted radio signals from the two different intermediate frequencies (IF1, IF2) to the transmission frequency; and only one coaxial line (427) which connects the first duplexer (444) of the donor unit (400) and the second duplexer (492) of the service unit (450) and transmits the converted radio signals over a distance between the first duplexer (444) of the donor unit (400) and the second duplexer (492) of the service unit (450) on the two different intermediate frequencies (ZF1, ZF2), wherein at least the donor unit (400) has an uplink donor antenna (40b) and a separate downlink donor antenna (40a) and the service unit (450) has an uplink service antenna (50b) and at the same time has a separate downlink service antenna (50a).

Description

[0001] The invention relates to a repeater for forwarding radio signals

[0002] To meet the demand for ever-increasing data rates in wireless networks, millimeter-wave frequencies are currently being investigated, and it has already been confirmed that these frequencies will be used in the successor standard to LTE (5G). Applications for these frequencies range from fixed wireless access (FWA) to typical mobile networks.

[0003] Mobile network coverage in the millimeter wave range is more limited than with conventional mobile frequencies. For example, free-space attenuation at 28 GHz is 20 to 30 dB higher than with conventional mobile frequencies. In addition, there are significantly higher propagation losses due to vegetation and high penetration losses through building materials such as glass and concrete. Further complicating the situation is the fact that propagation around house corners or over rooftops is not possible in this frequency range due to high diffraction losses (see "Millimeter Wave Mobile Communications for 5G Cellular: It Will Work!" by Theodore S. Rappaport et al., IEEE Access, vol. 1, pp. 335-349, 10 May 2013).

[0004] Furthermore, the performance of available analog hardware is limited (see 3GPP Technical Report No. 38.803 - v 14.2.0 from September 2017). The radiated power on the transmitter side is limited, in particular, by the efficiency of the power amplifiers. On the receive side, high line losses and the available LNA (low-noise amplifier) ​​technology limit the noise figure. This means that a nationwide network must be built with a denser mesh, which leads to increased costs (CAPEX and OPEX).

[0005] One solution to cost-effectively increase network coverage is the use of repeaters or relay technologies. Repeater functionality is already known from GSM, UMTS, and LTE networks (see 3GPP Technical Specifications TS 25.106, 25.107, 25.113, 25.116, 25.143, 25.153, 36.106). During the development of LTE-A, so-called relay nodes were also introduced in 3GPP Release 10 (3GPP TS 36.116, 36.117, 36.216).

[0006] Given the above-mentioned background, a solution to the network coverage problem, including in the millimeter wave range and future mobile communications standards, using repeaters is desirable. However, precisely because of the restrictions described above, concrete solutions pose a particular technical challenge that cannot be addressed with the current state of technology.

[0007] Repeaters for forwarding radio signals are known in the art. The repeater receives radio signals from a transmitter at a transmission frequency from one direction, amplifies the signals, and radiates the received radio signals in another direction. An example of such a repeater is shown in US patent US 7,577,398 B2 (Andrews LLC), which discloses a repeater with a housing having two opposite surfaces. At least one antenna is mounted on each of the two opposite surfaces, and the antennas radiate radio signals in opposite directions. Within the housing, a circuit is provided that forwards the signals between one of the antennas and the other antenna.

[0008] The repeater system described in this document is suitable, for example, for supplying the interior areas of a building. Several patent documents are known for supplying wireless networks within buildings. For example, US patent US 6 374 119 B1 (Jun et al.), international patent application no. WO 98 / 54844 A1 (LGC Wireless), European patent no. EP 1 224 821 B1 (Qualcomm), and German patent application no. DE 10 2015 011 875 A1 (Kathrein) describe such a system.

[0009] Fig. 1 and Fig. 2 illustrates the typical structure of state-of-the-art repeater solutions. Repeater 10 has a donor antenna 40 and a service antenna 50. Donor antenna 40 receives signals from a base station 20, and service antenna 50 transmits radio signals to a mobile station 30, such as a smartphone or tablet. The donor antennas 40 and service antennas 50 connected to repeater 10 can be installed at varying distances from repeater 10, depending on the specific situation at the installation site.

[0010] In such cases, the donor antennas 40 and the service antennas 50 are connected to the repeater 10 via coaxial cables 45 and 55. The coaxial cables 45 and 55 used for this purpose are known to exhibit frequency-dependent signal attenuation, which increases with increasing frequencies and cable length (see https: / / de.wikipedia.org / wiki / Koaxialkabel).

[0011] The repeater itself contains two transmission paths. The upper transmission path in these figures includes a low-noise downlink amplifier 110, a downlink bandpass filter 120, and a downlink power amplifier 130 in a downlink (DL) path. The lower transmission path is the uplink (UL) path and includes a low-noise uplink amplifier 160, an uplink bandpass filter 170, and an uplink power amplifier 180. The donor antenna 40 is connected to a first duplexer 100, which selects the downlink path or the uplink path via filter separation in Frequency Division Duplex (FDD) operation. The service antenna 50 is connected to a second duplexer 150, which also selects between the downlink path and the uplink path via a filter function in FDD operation.

[0012] In Fig. Figure 2 shows a similar prior art embodiment, this embodiment being a time division duplex implementation. Here, the first duplexer 100 is replaced by a first switch 105 and the second duplexer 150 by a second switch 155. The other components are the same as the elements in Fig. 1 and have the same reference numerals.

[0013] In Fig. Figure 3 is a highly simplified illustration of where the signal attenuation (ATT) of the coaxial lines 45, 55 comes into play in the system as a function of frequency (f) and cable length (I). The signal attenuation also scales with the diameter of the cable used in the coaxial lines 45, 55. As the diameter (d) decreases, the attenuation of the coaxial lines increases. These line-borne losses are approximately 160 dB / 100 m at a useful frequency of, for example, 28 GHz. With a typical repeater gain of 50 dB, a total cable length of approximately 32 m from the donor antenna 40 to the repeater 10 and further to the service antenna 50 would already attenuate the entire signal amplification back to the level received at the donor antenna. The installation of a repeater system, which is advantageous in terms of signal amplification, as is common on building roofs and at road intersections, cannot be carried out in this way or can only be carried out to a limited extent.

[0014] Document US 2019 / 0 020 401 A1 discloses an active repeater device comprising a first and a second section. The first section receives an RF signal, which is converted into an analog baseband signal. The converted signal is converted into an encoded data signal and transmitted by the second section as an RF signal to a terminal device.

[0015] The document US 2018 / 0 138 967 A1 teaches a separation of a signal into a high-band and a low-band part, whereby after separation each part is filtered by its own bandpass filter.

[0016] Document WO 2018 / 009035 A1 discloses a 5G building relay system and a 5G building relay method for sharing an RF cable in a building to provide a 5G communication service in the building.The 5G building relay system includes: a 5G signal delivery device for converting 5G RF signals into IF signals and delivering the IF signals via a pre-installed RF cable in the building; an MHU for receiving and transmitting the IF signals; a coupling device for combining the IF signals with radio signals other than 5G received by a ROU pre-installed in the building and delivering the combined signals via the RF cable; a distribution device for receiving the combined signals and separating and distributing the 5G IF signals from the combined signals; and a DRU for converting the distributed IF signals into millimeter-wave RF signals and wirelessly transmitting the RF signals to a 5G terminal.

[0017] Document US 2002 / 0 039 885 A1 discloses a repeater device for transmitting a radio frequency (RF) signal into an environment shielded from the RF signal, comprising a master transceiver unit having a master port that receives the RF signal, a local oscillator (LO) that generates an LO signal at an LO frequency, and a frequency divider that divides the LO frequency of the LO signal by an integer to generate a divided LO signal. The master transceiver unit also includes a master mixer coupled to the master port and the divider, which generates an intermediate frequency (IF) signal in response to the RF signal and the LO signal.The apparatus comprises one or more slave transceiver units, each unit positioned within the environment shielded from the RF signal, and a frequency multiplier that generates a recovered LO signal at the LO frequency by multiplying the frequency of the divided LO signal by the integer, a slave mixer coupled to the multiplier and generating a recovered RF signal in response to the recovered LO signal and the IF signal, and a slave port coupled to the slave mixer and receiving the recovered RF signal therefrom and transmitting the recovered RF signal into the enclosed environment.The apparatus further comprises one or more cables coupled between the master transceiver unit and the one or more slave transceiver units and transmitting the IF signal and the split LO signal between the master transceiver unit and the one or more slave transceiver units.

[0018] The invention is therefore based on the object of developing an improved repeater system. According to the disclosure, a repeater system is provided according to the independent claim. Developments are presented in the dependent claims.

[0019] The separation of the antennas is necessary for a repeater that transmits the radio signals in TDD mode, from the Fig. 1 and Fig. 2 shown state of the art is not known. As can be seen from the Fig. 2, repeaters in a TDD design require multiple switches to switch the antennas between the signals on the transmission paths (uplink path and downlink path). These switches cause significant insertion loss in the centimeter and millimeter wave range, which has a very detrimental effect on the overall performance of the repeater system. However, the repeater system in this document does not have an internal synchronization signal to control the switches, and this synchronization signal would otherwise have to be generated from the received radio signals. The separate antennas eliminate the need to derive or generate the synchronization signal.

[0020] According to the 5G standard, the frames in a radio signal do not have a fixed time grid and therefore no predetermined frame length, which further complicates switching between the transmission paths and thus the synchronization of the radio signals with a single, split donor antenna. Separating the antennas also avoids delays in signal transmission due to the switching times otherwise required for the switches and the derivation of the synchronization signal. Beam steering, which is used in 5G transmissions, can pose an additional challenge for synchronization, as this means that the base station signals are not always available, but only when the beam is pointing at the repeater system (10).

[0021] The invention will now be explained in more detail with reference to the figures. They show: Fig. 1 shows a first example of a repeater system according to the prior art in an FDD design; Fig. 2 a second example of a repeater system according to the state of the art in TDD design; Fig. 3 an explanation of the losses in coaxial cables; Fig. 4A-4F several aspects of the repeater system; Fig. 5A-5C several aspects of the repeater system with a common cable Fig. Figure 6 shows a repeater system with a common cable at two different intermediate frequencies; Fig. 7 an application of the repeater system with multiple service antennas; Fig. 8A and Fig. 8B a sectorization of the transmission channels; Fig. 9A is a block diagram of a repeater with four service antennas; Fig. 9B the modular structure of the repeater system; Fig. 10 the modular structure of the repeater system; Fig. 11A-11E several aspects for the bundling of radio signals; Fig. 12A-12E repeater system in the frequency domain; Fig. 13 the control of the repeater system; Fig. 14 the use of the repeater system in a building; Fig. 15 the control of the repeater system.

[0022] Fig. 4A shows an example with a first frequency converter unit 400 and a second frequency converter unit 450, which, contrary to the claimed invention, are connected not via (only) one, but via two cables 420 and 425. The cables 420 and 425 are connected to the units 400 and 450 via plugs and connectors and can also include other passive and active elements. The first frequency converter unit 400, which is referred to below as donor unit 400, has a downlink donor antenna 40a for a downlink path DL and an uplink donor antenna 40b for an uplink path UL. The downlink path DL in the donor unit 400 includes a donor downlink bandpass filter 405, which is connected to the donor antenna 40a and filters the received radio signals. A low-noise donor downlink amplifier 410 is connected to the output of the downlink bandpass filter 405 and amplifies the received signals in the filtered frequency range. The output of the low-noise donor downlink amplifier 410 is connected to a donor downlink mixer 415. This donor mixer 415 is a frequency downconverter that converts the frequency of the received signals to a (low) intermediate frequency.

[0023] The uplink path UL in the donor unit 400 further comprises a donor uplink mixer 430, a donor uplink power amplifier 435, and a donor uplink bandpass filter 440. The uplink path UL receives the signals transmitted by the second frequency converter unit 450, which is further referred to as the service unit 450. The donor uplink mixer 430 is an upconverter and converts the frequency of the received signals from the intermediate frequency IF to the transmission frequency. The signals are then amplified in the donor uplink power amplifier 435 and filtered in the donor uplink bandpass filter 440. The output of the donor uplink bandpass filter 440 is connected to the second donor antenna 40b, and the filtered signals are transmitted at the transmission frequency.

[0024] The service unit 450 includes a service downlink mixer 455 in the downlink path DL, which is connected to the input of a service downlink power amplifier 460. The service downlink mixer 455 is an upconverter that converts the signals to be transmitted from the donor unit 400 from the intermediate frequency to the transmission frequency. The service downlink power amplifier 460 amplifies the signals. The output of the service downlink power amplifier 460 is connected to the input of a service downlink bandpass filter 465, which filters the signals. The output of the service downlink bandpass filter 465 is connected to the downlink service antenna 50a, and the downlink service antenna 50a radiates the signals at the transmission frequency.

[0025] The uplink path of service unit 450 is connected to the uplink service antenna 50b, which is connected to the input of a service uplink bandpass filter 470. This service upload bandpass filter 470 filters the received radio signals in a specific frequency range and forwards only these filtered radio signals to a low-noise service upload amplifier 475, where the radio signals are amplified. The amplified signals from the low-noise service uplink amplifier 475 are forwarded to a service uplink mixer 480, where they are converted to an intermediate frequency for transmission to the donor unit 400 via cable 425 (a coaxial line).

[0026] In the donor unit 400, the received signals on the uplink path are forwarded to a donor uplink mixer 430 and upconverted to the transmit frequency for transmission, as described above.

[0027] By converting the frequencies between the donor unit 400 and the service unit 450 to a lower intermediate frequency (IF), it is possible to use longer coaxial cables for the cables 420 and 425. This means that the donor unit 400 and the service unit 450 can be operated separately from each other.

[0028] Fig. Figure 4B shows an aspect of the repeater system 10 in which identical elements are present in the donor unit 400 and the service unit 450. These identical elements are identified by the same reference numerals.

[0029] The Fig. The aspect shown in Figure 4B differs from the aspect of Fig. 4A by a single donor antenna 40 instead of the two donor antennas 40a and 40b and a single service antenna 50 instead of the two service antennas 50a and 50b. The single donor antenna 40 is connected to the donor unit 400, and the single service antenna 50 is connected to the service unit 450.

[0030] The donor unit 400 has a donor switch 402 connected to the single donor antenna 40 and to both the downlink path DL and the uplink path UL. The donor switch 402 is used to switch the donor antenna 40 between the downlink path DL and the uplink path UL, depending on whether signals are being received or transmitted via the donor antenna 40. Similarly, a service switch 490 is present in the service unit 450. This service switch 490 is also connected to the downlink path DL and the uplink path UL of the service unit 450 and to the single service antenna 50. The service switch 490 can switch the signals to and from the service antenna 50 between the two paths (downlink path DL and uplink path UL).

[0031] In a third aspect of the invention ( Fig. 4C), the donor downlink bandpass filter 405 and the donor uplink bandpass filter 440 are replaced by a single donor bandpass filter 405 / 440 and the Fig. 4B is displaced behind the common bandpass filter 405 / 440. Likewise, in the service unit 450, the service downlink bandpass filter 465 and the service uplink bandpass filter 470 are replaced by a common service bandpass filter 465 / 470 and the Fig. 4B known service switch 490 has been relocated between the common service bandpass filter 465 / 470 and the service downlink power amplifier 460 and the low-noise service uplink amplifier 475.

[0032] A fourth aspect of the repeater system 10 is Fig. 4D. In this aspect of the invention, the two cables 420, 425 have been replaced by a common cable 427 (ie, a coaxial line) in accordance with the claimed invention. As can be seen from Fig. As can be seen from Figure 4D, the donor unit 400 therefore requires a donor output switch 403, which switches the radio signals between the common cable 427 and the donor downlink mixer 415 and the donor uplink mixer 430. A service input switch 452 is also present in the service unit 450. This service input switch 452 is also connected to the service downlink mixer 455 in the downlink path DL and to the service uplink mixer 480 in the uplink path UL of the service unit 450 and switches the radio signals to the common cable 427.

[0033] A fifth aspect of the repeater system 10 is Fig. 4E. As can be seen from the Fig. 4E, the common cable 427 is present between the donor unit 400 and the service unit 450. It can also be seen that the donor switch 402 and the service switch 490 are in positions as shown in Fig. 4C are present.

[0034] Another aspect of the invention is in Fig. 4F. In the aspect of Fig. 4F, a common cable 427 is also provided between the donor unit 400 and the service unit 450. This aspect otherwise corresponds to the first aspect of the invention ( Fig. 4A) with the two donor antennas 40a and 40b and the two service antennas 50a and 50b. Of course, this aspect of the invention requires the donor output switch 403 and the service input switch 452 to switch the radio signals to the common cable 427 at the intermediate frequency IF.

[0035] Another aspect of the invention is in Fig. 5A. This aspect of the invention largely corresponds to the previous aspects of the invention, with this aspect differing in that the common cable 427 transmits signals at two different frequencies IF1 and IF2. For example, the radio signals on the downlink path DL between the donor unit 400 and the service unit 450 are transmitted at a first intermediate frequency IF1 via the common cable 427, and the radio signals on the downlink path DL between the service unit 450 and the donor unit 400 are transmitted at a second frequency IF2. A donor duplexer 500 is present in the donor unit 400, which redirects the radio signals to the appropriate path. A service duplexer 510 is also present in the service unit 450, the function of which is to redirect the radio signals to the appropriate paths in the uplink (UL) and downlink (DL).

[0036] In Fig. 5B shows a similar aspect of the repeater system 10, wherein the two donor antennas 40a and 40b of the repeater system 10 are Fig. 5A is replaced by a single donor antenna 40. Accordingly, the first donor unit 400 also includes a donor switch 402. The two service antennas 50a and 50b of Fig. 5A are also connected by a common service antenna 50 in the aspect of Fig. 5B and a service switch 490 is also present in the service unit 450.

[0037] In Fig. 5C, the donor switch 402 is relocated in the donor unit 400, as can be seen from the aspect of the Fig. 4C and Fig. 4E is known. The donor switch 490 is also advanced in the service unit 450.

[0038] Fig. 6 shows a further aspect of the invention with a common cable 427, which transmits radio signals at two different frequencies IF1 and IF2. As can be seen from the figures, the donor unit 400 contains two downlink paths DL and two uplink paths UL, each with a mixer 600a, 600b, 610a, 610b. The mixers 600a, 600b, 610a, 610b can convert the frequency of the radio signals either to the intermediate frequency IF1 or to the intermediate frequency IF2, and these are forwarded to the service unit 450, in which the radio signals are converted back to the transmission frequency. The service unit 450 also contains two downlink paths DL and two uplink paths UL, each with a mixer 650a, 650b, 660a, 660b. The other elements are from the Fig. 4A-4F and 5A-5D known.

[0039] An application of the repeater system 10 of this document is in Fig. 7. In this Fig. 7 shows a plurality of service units 450-1, 450-2, 450-3, and 450-4, each connected to a service antenna 50-1, 50-2, 50-3, and 50-4. The plurality of service units 450-1, 450-2, 450-3, and 450-4 are connected via coaxial lines 720-1, 720-2, 720-3, and 720-4 to a splitter 700, which splits and forwards the radio signals from the donor unit 400 to the plurality of service units 450-1, 450-2, 450-3, and 450-4. The splitter 700 is connected to the donor unit 400 via a cable 710. This Fig. The aspect of the invention shown in Figure 7 has the advantage that different radiation characteristics for the radio signals can be used in the majority of the service units 450-1, 450-2, 450-3 and 450-4.

[0040] Fig. Figure 8A shows an example of these radiation characteristics, where the donor antenna 40 receives radio signals in four different frequency ranges f1, f2, f3 and f4 from the base station (not shown) and transmits them via a Fig. The repeater system 10 known from FIG. 7 can radiate the received radio signals in four different directions in all received frequency ranges f1, f2, f3, and f4 in a kind of "cube shape" via the four different service antennas 50a-d. Each service antenna 50a-d radiates all four frequency ranges f1, f2, f3, and f4.

[0041] In contrast, Fig. 8B shows another variation of the radiation characteristics. In this Fig. 8B, each service antenna 50a-d radiates radio signals in only one frequency range f1, f2, f3, f4. In other words, the radio signals received via the donor antenna 40 in the four frequency ranges f1, f2, f3, and f4 are each radiated in one direction at different frequency ranges f1, f2, f3, or f4 via the respective service antennas 50a-d. With the help of this repeater system, specific sectors (reception areas) can be supplied with radio signals of a specific frequency; the radio signals in other sectors have a different frequency.

[0042] Fig. 9A shows a block diagram for the implementation of the repeater system 10 from Fig. 7 with a donor unit 400, which is connected via cable 427a-c to four different service units 450a-c. As can be seen from the Fig. As can be seen in Figure 9A, the donor unit 400 is connected to a signal selector 900. The signal selector 900 comprises four bandpass filters, each of which selects only the radio signals of one of the four intermediate frequencies IF1, IF2, IF3, and IF4, and transmits these selected radio signals to a corresponding service unit 450-1, 450-2, 450-3, and 450-4.

[0043] Fig. Figure 9B shows the modular design of repeater system 10. As can be seen from the figure, the donor antenna with bandpass filter 940 is separated from the electronic module 960 in the donor unit 400. The service units 450 are also divided into modules. The electronic modules 960a, 960b, 960c, and 960d are similarly constructed and are separated from the service antennas 50 with bandpass filters 950a, 950b, 950c, and 950d. This modular design is also shown in Fig. 10 presented in a simple form.

[0044] Fig. 11A-11E show the use of the repeater system 10 to bundle the radio signals on the service side. The radio signals are received via a line 1110 from the donor unit 400 and distributed or reshaped in a distribution network 1120 or beamforming network (also referred to as a beamforming network or lobe formation network) and forwarded to the service antennas 50. Through this distribution, various radiation patterns of the service antennas 50 can be created. For example, FIG. Fig. 11A a simple radiation pattern with a main lobe 1130 and two secondary lobes 1135.

[0045] The use of the dielectric lens 1140 is in Fig. 11B. This results in a very strong main lobe 1150 with side lobes 1155. In Fig. Figure 11C shows a beamforming network with a dielectric lens 1140, which also has a radiation pattern with a strong main lobe 1160 and side lobes 1165, which is swept in this aspect of the invention. The sweeping of the main lobe 1170 with side lobes 1175 of the radio signals by the beamforming network 1125 is known and is described in Fig. 11D. In a further aspect of the invention, a Rotmann lens 1180 is used as a distribution network. This allows the radio signals to be bundled into a plurality of radiation directions (beams) 1190.

[0046] The invention can also be used for repeater systems 10 with frequency division duplex (FDD), as can be seen from Fig. 12A-12E. The structure of the respective figures is similar to that for repeater systems 10 with time-division duplex (TDD). Fig. Figure 12A shows the transmission of radio signals between the donor unit 400 and the service unit 450. Fig. 12B shows, in accordance with the claimed invention, a joint transmission of the radio signals on the common cable 427 with two different intermediate frequencies in IF1 and IF2 with a duplexer 444 in the donor unit 400 and a duplexer 492 in the service unit 450. Fig. 12C illustrates the use of a single donor antenna 40 and a single service antenna 50 by combining the uplink and downlink signals at the donor antenna 40 with a duplexer 442 and combining the uplink and downlink signals at the service antenna 50 with a duplexer 494. Fig. 12D shows the repeater system from Fig. 12C with two different transmission paths and Fig. 12E shows how the common cable 427 can be used with the donor unit 400 and the service unit 450 by using different intermediate frequencies IF1, IF2, IF3, and IF4. Additional donor units 400 and service units 450 can be added.

[0047] In Fig. 13 shows that the control of the repeater system 10 can be controlled externally via an IT network 1310 via a so-called IoT modem 1300.

[0048] An application of the repeater system 10 of this document is, for example, in Fig. 14 and is located in a building 1405 that is already wired with coaxial lines 1420. These existing coaxial lines can be reused using the repeater system 10 of this document. In this case, the intermediate frequency IF is selected such that the signals on the existing coaxial line 1420 are not interfered with by the radio signal transmitted between the donor unit 1400 and the service unit 1410. This allows mobile stations (user equipment) 1430 in a building to be supplied with radio signals. Fig. Figure 15 shows another aspect of the repeater system 10 of this document. At least one transmission path (e.g., 1530) via lines 1540 between the donor unit 1500 and the service unit 1510 can be supplied with additional control signals and, for example, transmit data from or to the IT network 1560 via an additional transmission path 1550. Reference symbol 10 repeaters 20 base stations 30 mobile stations 40 Donor antenna 40a Downlink donor antenna 40b Uplink donor antenna 45 coaxial cable 50 Service antenna 50a downlink service antenna 50b uplink service antenna 55 coaxial cable 100 First Duplexer 105 First switch 110 downlink amplifiers 120 downlink bandpass filters 130 downlink power amplifiers 150 Second duplexer 155 Second switch 160 uplink amplifiers 170 uplink bandpass filters 180 uplink power amplifiers 400 First frequency converter unit / donor unit 402 Donor Switch 403 Donor output switch 405 donor downlink bandpass filter 410 donor downlink amplifiers 415 Donor downlink mixer 420 cable 425 cables 427 Common cable 430 Donor Uplink Mixer 435 Donor Uplink Power Amplifiers 440 donor uplink bandpass filter 442 duplexers 444 duplexers 450 service unit 452 Service entrance counter 455 Service downlink mixing device 460 Service Downlink Power Amplifiers 465 service downlink bandpass filter 470 service uplink bandpass filter 475 service uplink amplifiers 480 Service Uplink Mixer 490 service counters 492 duplexers 494 duplexers 500 donor duplexers 510 Service Duplexer 600a,b mixing device 610a,b mixing device 650a,b mixing device 660a,b mixing device 700 splinters 710 cable 900 signal selector 940 donor antenna with bandpass filter 950 service antenna with bandpass filter 960 electronic module 1110 line 1120 distribution network 1125 Beamforming Network 1130 Main lobe 1135 side lobe 1140 Dielectric lens 1150 main lobe 1155 side lobe 1160 main lobe 1165 side lobe 1170 main lobe 1180 Rotmann lens 1190 Beam direction 1300 IoT Model 1310 ITG Network 1400 donor units 1405 buildings 1410 Service Unit 1420 coaxial cables 1430 user equipment 1500 donor units 1510 Service Unit 1530 transmission path 1540 lines 1550 Additional transmission path 1560 IT network

Claims

[1] Repeater system (10) for forwarding radio signals transmitted during operation in FDD mode, comprising: a donor unit (400) with a first duplexer (444) for converting the frequencies of the radio signals from the transmission frequency to two different intermediate frequencies (IF1, IF2); a service unit (450) with a second duplexer (492) for converting the converted radio signals from the two different intermediate frequencies (IF1, IF2) to the transmission frequency; and only one coaxial line (427) which connects the first duplexer (444) of the donor unit (400) and the second duplexer (492) of the service unit (450) and transmits the converted radio signals over a distance between the first duplexer (444) of the donor unit (400) and the second duplexer (492) of the service unit (450) on the two different intermediate frequencies (ZF1, ZF2), wherein at least the donor unit (400) has an uplink donor antenna (40b) and a separate downlink donor antenna (40a) and the service unit (450) has an uplink service antenna (50b) and at the same time has a separate downlink service antenna (50a). [2] Repeater system (10) according to claim 1, wherein the radio signals are transmitted in the centimeter and millimeter range during operation. [3] Repeater system (10) according to claim 1 or 2, wherein the donor unit (400) has a separate donor uplink path and a separate donor downlink path, and the service unit (450) has a service uplink path and a separate service downlink path, wherein the first duplexer (444) selects the donor downlink path or the donor uplink path via a filter separation in the FDD operation, and wherein the second duplexer (492) selects the service downlink path or the service uplink path via filter separation in the FDD operation. [4] The repeater system (10) of claim 3, wherein the donor downlink path comprises a donor downlink amplifier (410) and a donor downlink mixer (415), the donor downlink mixer (415) being connected to the coaxial line (427). [5] Repeater system (10) according to claim 4, wherein the gain of the donor downlink amplifier (410) is adjustable and the total gain is adjusted such that the sum of the total gain between the downlink donor antenna (40a) and the uplink service antenna (50b) is less than the decoupling between the uplink donor antenna (40b) and the downlink service antenna (50a). [6] Repeater system (10) according to one of the preceding claims, comprising further service units (450) and a plurality of coaxial lines (427) which each connect the donor unit (400) and the further service units (450) to one another and transmit the converted radio signals over a distance between the donor unit (400) and the connected further service units (450). [7] Repeater system (10) according to claim 6, wherein the further service units (450) are adapted such that the service units (450) transmit and receive radio signals in different directions. [8] Repeater system (10) according to claim 7, wherein the service units (450) are located at one location and radiate into different, possibly overlapping, sectors. [9] Repeater system (10) according to one of claims 6 to 8, wherein the service units (450) transmit and receive radio signals of different transmission frequencies during operation. [10] Repeater system (10) according to one of claims 1 to 7, wherein the donor unit (400) comprises a donor uplink bandpass filter (440) connected to the uplink donor antenna (40b) and a donor downlink bandpass filter (405) connected to the downlink donor antenna (40a) for transmitting the radio signals. [11] Repeater system (10) according to one of the preceding claims, wherein the decoupling between the uplink donor antenna (40b) and the downlink donor antenna (40a) is at least 40 dB.

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