Interface module for a unit of an antenna distributor system and antenna distributor system

0001The invention relates to an interface module for a unit designed for the transmission and / or amplification of communication signals within an antenna distribution system. The invention further relates to an antenna distribution system having at least one master unit and having a number of remote units connected to the master unit. The invention is concerned with the problem of ensuring sufficient radio communication on so-called essential, non-public communication channels, the train or radio service, emergency response forces, rescue services, police, fire brigades, paramedics and other assistants released and a public Radio communication may not be used. It also deals with the entire operational mobile communications of applications with special security tasks (BOS) in industry, public transport (PT), public authorities, airports and the military.

0002For information transmission on the essential communication channels in the VHF range, the amplitude modulation is usually used; if necessary, the frequency modulation is used. In modern digital trunked radio systems (eg Terrestrial Trunked Radio TETRA, TETRAPOL, P25,), the phase modulation (π / 4-DQPSK, π / 8-D8PSK or CQPSK) and quadrature amplitude modulation (4-, 16- or 64-QAM) are also used. Due to the small modulation stroke or Low transmission rates require only a small channel bandwidth. For bidirectional communication, the modes of exchange traffic (simplex), oncoming traffic (duplex) or conditional oncoming traffic (semi-duplex) are used. In the case of alternating traffic, only one band of the essential communication signal is occupied. The exchange of information takes place alternately and with a time delay. When oncoming traffic is alternately a defined subband or used a defined upper band. Alternate communication can happen at the same time. In this case, so-called relay stations are used to set up the communication. Mobile units and base stations send in the lower band and receive in the upper band. The relay stations themselves, which increase the range, receive the calls in the lower band and send them out again in the upper band. The separation of the calls between an uplink direction (towards a base station) and a downlink direction (towards a mobile terminal) thus takes place by a frequency separation.

0003During a catastrophic event, a salvage or rescue operation, in the case of accidents involving air, water or land, rapid and undisturbed communication is required, if possible, between all involved emergency services. An on-site radio communication of the emergency services is already limited by the fact that different units, such as fire, police and civil protection, exchange information on different communication channels with different transmission methods. In addition, the communication technologies and transmission frequencies provided for the emergency are not optimized for the technical possibilities of today's modern mobile radio networks. At the frequencies of the essential communication signals below 700 MHz, which are activated for emergency purposes, the emergency services can communicate with each other over comparatively long distances on site. However, the repeater technology possibly present within closed buildings, vehicles or tunnels for modern mobile radio networks can not be used optimally for the transmission of the essential communication signals due to the long wavelengths and due to the comparatively simple radio transmission method provided for the emergency. Modern mobile networks communicate in the gigahertz range. To encode the signals complex modulation methods are used. To separate the uplink and downlink communication in particular the method of time-division duplexing (TDD) is used in addition to the frequency separation, but the time constants are smaller by orders of magnitude than those in the exchange traffic within an essential communication channel.

0004While on the one hand the transmission of essential communication channels places little demands on the bandwidth, on the other hand a very large dynamic range has to be ensured and a high isolation between the uplink and the downlink communication has to be implemented. Because of the large wavelengths of essential communication signals, the separation between each other and the isolation between the uplink and the downlink direction using channel-selective analog filters requires a considerable technical effort, which is sometimes associated with enormous costs.

0005Considerations of how to ensure sufficient communication on essential communication channels between task forces of different units or using a modern network architecture for the radio transmission of information, for example, from <patcit id="pcit0001" dnum="US20040070515A1"><text>US 2004/0070515 A1</text></patcit>, the <patcit id="pcit0002" dnum="US20050260983A1"><text>US 2005/0260983 A1</text></patcit> or the <patcit id="pcit0003" dnum="US200801711527A1"><text>US 2008/01711527 A1</text></patcit> The transmission of sampled high-frequency signals in distributed antenna systems is known, for example, from US Pat <patcit id="pcit0004" dnum="US5852651A"><text>US 5,852,651</text></patcit>, In the<patcit id="pcit0005" dnum="WO2008092067A2"><text>WO 2008/092067 A2</text></patcit> a modular wireless communication platform is described. In the<patcit id="pcit0006" dnum="US2009046624A1"><text>US 2009/046624 A1</text></patcit> For example, a system and method for inserting signals into a communication system are described.

0006The object of the invention is to provide a technical solution that enables sufficient communication of emergency services on essential communication channels using a modern radio network architecture. At the same time, the advantages known from modern radio network architecture should also be made available for communication on essential communication channels.

0007The stated object is achieved according to the invention by an interface module for a unit designed for the passage and / or amplification of communication signals within an antenna distribution system, the interface module having a first analog interface for forwarding and receiving communication signals of mobile terminals, a second interface for digital or analog transmission and reception of communication signals of the antenna distribution system, at least one signal path for forwarding the received communication signals between the two interfaces, and a controllable digital unit accommodating the signal path with means for digitizing incoming and for analog conversion outgoing communication signals. In this case, the digital unit is designed to identify in the digitized essential communication signals, to hide the remaining signals and to forward the selected essential communication signals.

0008The control and / or implementation of essential communication signals between different remote units, an optionally connected base station or an optionally connected additional network is effected by a central interface module in the master unit. It should be noted that an exchange between individual branches of the distribution network is only considered in digital form. A remote unit and a master unit represent units of the antenna distribution system in this sense.

0009In other words, the invention provides an interface module for equipping one or more remote units and a master unit, as are known for a modern antenna distribution system of a mobile radio network. Such a remote unit or a plurality of such remote units is used, in particular in a radio shadow, within closed buildings, in tunnels, in trains, at railway stations, in stadiums, etc. to ensure sufficient communication via radio with mobile terminals. In this case, a master unit connected to a base station of the respective radio network is located in the vicinity of the tunnel, the building or in general the shaded location and transmits communication signals between the base station and the remote units, which are arranged within the building or generally in the radio shadow. If necessary, the remote units transmit the received communication signals more intensively and, on the other hand, receive communication signals from mobile terminals which are finally fed in the uplink direction via the master unit to the base station. The remote units are commonly referred to as relay stations. This radio network architecture has the advantage that a central control of the remote units via the master unit is possible. The connection of the master unit to the base station can be wired or wireless. The remote units themselves are, for example, wired or optically coupled to the master unit. However, the remote units can also advantageously be designed as so-called off-air repeaters, which are connected to the master unit via radio. Included in the described radio network architecture are also several master units, which in turn are in turn connected to a multiplicity of remote units. It should be noted that in public mobile networks no so-called "direct mode", ie a direct connection between two mobile devices is possible.

0010The invention is now based in particular on the idea of ​​using a remote unit for the transmission and integration of essential communication signals into the given mobile radio network. In particular, it should also be possible to enable bidirectional communication on essential communication channels via one or more remote units with the given technology. Similarly, the or each master unit should be trained to receive, relay and distribute the essential communication signals accordingly.

0011In this case, the invention proposes an interface module, which should largely be dispensed with analog separation means such as duplexers or analog filters in order to separate the essential communication signals with each other or sufficiently isolate the uplink and downlink directions. Because of the large wavelengths of the essential communication signals such a design for the separation of the narrow-band channels requires an enormous amount of space and is also associated with high costs. Rather, the invention is the way to implement a digital unit in the transmission or signal path of the antenna distribution system for communication with a mobile terminal, which first digitized the incoming signals to subsequently demodulate to baseband. This is achieved by providing a suitably equipped interface module.

0012A high dynamic range required for the essential communication signals can be realized in particular by a narrow-band digital oversampling with subsequent digital down conversion. It should be noted that in the case of a digital modulation no decryption of the most crypted baseband data is required. The time offset associated with this scheme known as "Decode and Forward" or Time requirement is not to be tolerated in usual portable radio nets, plays however only with the mostly mutually operated communication signals of the essential services only a subordinate role. Insofar as the digital unit remains within the given communication sequence enough time to a sufficient rastering of the incoming communication signals and on a digital level to a corresponding identification and to a separation of the other, unnecessary for the essential interface module communication signals. In particular, the digital unit can identify the frequencies, the type of modulation of the transmission signals and the transmission method used, thus distinguishing essential communication signals from each other and from the remaining communication signals. In a preferred embodiment, the digital unit is instructed in one or more remote units via a central master unit for selection, forwarding or conversion to another band or another frequency.

0013The interface module is in particular designed such that it ensures the exchange of information of the essential communication signals detached from the other communication signals of the mobile network. It is preferred insofar as an additional module of an existing remote unit, but in particular on their existing computer or Software architecture can be used. In this respect, in particular, the digital unit described here does not have to be designed as a separate digital unit. Rather, this can be done by an existing, for the transmission of the communication signals of the mobile network in a TDD or Fully implemented FDD architecture provided digital unit. The necessary functions and properties for the present invention can then be realized by appropriate programming of the given computer or processor architecture.

0014The signal path of the interface module is given in the simplest case by a signal line which connects the two interfaces. Such a signal line would possibly be sufficient for an alternating traffic of the uplink and the downlink signals, but does not provide enough possibilities to include further essential communication signals of other transmission methods such as duplex or semiduplex. For this reason, the signal path is expediently divided into a plurality of separate signal paths for the uplink direction and a plurality of separate signal paths for the downlink direction. A time division duplex (TDD) or a frequency duplex method (FDD) is then used to separate the two communication directions corresponding to the two given signal lines.

0015The proposed architecture of the interface module further makes it possible to transmit the received essential communication signals to the master unit or to one or more remote units, in particular coded, frequency offset or further processed in any other way. A corresponding control computer connected to the remote unit or the master unit is then able to identify the essential communication signals received from a specific remote unit, to instruct the forwarding and / or conversion in the same or another remote unit. Furthermore, the master unit optionally has the option of coupling these signals into a landline, for example. Conversely, in the downlink direction, the master unit can reprocess the transmission of essential communication signals accordingly and instruct it specifically to the respective remote unit. By addressing, the remote unit can in particular also identify the signals intended for it. Using appropriate control commands, the digital unit can be upgraded to the appropriate actions and enabled. In the uplink direction, it is preferable to recombine the separated, essential communication signal with the other information to be transmitted, intermodulation effects being prevented by a sufficient frequency offset of the separated signals relative to each other. The connection line between the master unit and the remote unit is designed in this case as a common signal line for transmitting the entire data exchange. In particular, an optical waveguide is provided for this purpose. A correspondingly configured coaxial line or a two-wire line for electrical signals is also possible.

0016In a further, not shown embodiment, a connection of several "off-air repeater" via a radio modem is conceivable.

0017In a further preferred embodiment, the digital unit is designed to detect characteristic signal parameters of the identified essential communication signals and also to forward them via the signal path. The transmission of such signal parameters allows a user to determine, for example, what type of essential communication signals are exchanged, with what frequency such communication takes place, or also, from which remote unit the transmitted essential communication signal originates. In particular, this allows a localization of the transmitting mobile terminal via a detection and forwarding of the received signal strength and / or a runtime detection. The type of transmission method for the essential communication signal can also be identified and, if appropriate, an automated adaptation of the digital unit can be carried out by means of the master unit. The interface module is then trained to establish the communication on the respective essential communication band with the appropriate transmission method. Particularly preferably, the digital unit is designed to switch between different transmission methods of the essential communication methods, in particular between a simplex, a duplex or a semi-duplex method.

0018In particular, when forwarding the characteristic signal parameters such as signal strength, frequency, frequency band and / or transmission method or Communication type of the identified essential communication signals are made a respective implementation of the corresponding communication signals in other essential communication channels, so that the forces of different units is possible to communicate with each other. In this case, the interface module is preferably designed such that the digital unit enables a conversion into different frequency bands and ensures transmission of the essential communication signals with different transmission methods in different frequencies.

0019In principle, digitization with a sufficient sampling rate in accordance with known sampling methods is possible. In principle, a modulation or a digital coding method for improving the transmission rate can also be used. For cost reasons and because of the primary purpose pursued here, however, it is sufficient to design the digital unit to digitize the communication signals in the baseband.

0020Advantageously, the digital unit is designed for a controllable delay and / or interruption of the forwarding of the essential communication signals in the direction of the first analog interface. This embodiment particularly relates to the formation of standing waves in buildings, train or road tunnels, or stadiums that occur especially in the long-wave communication signals of the essential communication channels. Such a situation is in particular a consequence of the interferences which occur in the overlapping region of the radiation radii of several remote units placed in such locations. The resulting spatial interference patterns depend strongly on the particular wavelength used. The ability to delay the downlink traffic of a remote unit for essential communication signals, can now actively interfere with the design of the resulting interference pattern. This operation, known as a single-frequency network, makes it possible to reduce dead spots for mobile receivers by, for example, deliberately delaying a correspondingly localized remote unit in its emission. Since all remote units emit in phase, destructive interference is avoided. Alternatively, a remote unit in the downlink direction can also be muted.

0021In a further preferred embodiment, the digital unit is designed for a controllable interruption of the forwarding of the essential communication signals in the direction of the second interface. In particular, reference is made to the fact that in the presence of multiple remote units, the transmitted essential communication signals a better signal-to signals have noise ratio, when the weakest signal information is not used to form the communication a whole. Based on a signal strength detection, the master unit can be automated in this respect or controlled from the outside mute the weakest in terms of the receiving side remote unit in the uplink direction. With this known as "up-link muting" method, an overall better transmission quality for the essential communication signals can be generated.

0022In the opposite direction can be suppressed by a short circuit switch in the DL path behind the amplifier, in its idle case, the transmission of noise. This is particularly advantageous in semi-duplex operation during the uplink time or in the case of the direct mode, in which no relay is required due to the level conditions.

0023For this purpose, in addition or independently, the digital unit of the interface module is designed to return the incoming essential communication signals in the direction of the first analog interface. In other words, a remote unit is thereby strengthened to a direct communication, wherein controlled information or the identified essential communication signals are passed to the master unit or one or more remote units or not. The essential communication signals obtained are to a certain extent reflected and amplified at the digital unit and, if necessary, switched on again in time or frequency to transmit the first analog interface for radio transmission. This direct mode makes it possible to improve the on-site radio communication between the emergency services. In particular, the "reflected back" received signal can be modified by the digital unit so that it can also be received and processed by the mobile terminals of the forces of other units. In this case, the thus-controlled remote unit effectively acts as a relay station that improves the range and transmission strength of the essential communication signals between the mobile terminals and, in particular, between the mobile task forces of different units, so that the coordination possibilities on site are significantly increased.

0024The digital unit is expediently designed for controllable frequency conversion between the frequency bands of essential communication signals. This allows - as already described above - the establishment of communication between mobile terminals of the emergency services of different units. In this case, the digital unit is preferably also additionally designed to take into account the particular transmission method used for the corresponding essential communication channels.

0025In order to enable central forwarding, control and monitoring of the information exchange, a communication unit is included in the interface module. The central controller is responsible for this, for example, a central control computer connected to the master unit. This communication unit may be an integral part of the digital unit. However, if, for example, a digital unit already implemented in an existing remote unit is used to execute the functions described above, it is advisable to provide a separate communication unit in the interface module, which ensures the data exchange between the master unit and the digital unit or controls. To connect the control computer to the master unit, the interface module is likewise to be provided, which then conversely receives the control data, prepares it and transmits it via the existing connection to the interface module in the remote unit. In this case, the data exchange can be realized for example by means of known and suitable networks, such as LAN or Ethernet. For example, such a digital data network also offers the possibility of assigning each remote unit its own address within the network. This address is then the respective digital unit or the respective remote unit can be addressed directly. The information transmitted between two or more remote units and / or the master unit are also uniquely identified by the address.

0026For this purpose, the communication unit for coupling the information and control data to the communication signal is preferably connected to the signal path. In other words, the data exchange regarding the information of the detected essential communication signals and the control data for the digital unit is applied to the signal transmitted between the remote units or the signal transmitted to the master unit. A central control computer, in particular connected to the master unit, is then able to identify the transmitted data within the digital data network and to redirect it via the master unit to the desired remote units. In the case of more complex switching tasks this computer can then be transferred to the central control of the digital units of the remote units. For this, the current status as well as further information about the type and frequency of communication on essential communication channels can be queried and displayed. The central control computer can also be part of the master unit itself, which is then intelligent.

0027For separating remaining communication signals from the essential communication signals to be separated, at least one analog filter unit for separating the frequency bands of incoming and outgoing analog essential communication signals is preferably included. By such an analog filter unit, for example, the high frequencies of the communication signals of the mobile network can already be hidden. As a result, interference signals can be eliminated in particular.

0028The stated object is further achieved according to the invention by an antenna distribution system having at least one master unit and having a number of remote units connected to the master unit, to which an interface module of the type described above is assigned or which are equipped with such -Unit for selectively controlling the digital units of the remote units and for receiving and forwarding the essential communication signals is formed.

0029Further advantageous embodiments thereof can be found in the subclaims directed to an antenna distribution system. To fulfill the stated tasks, the master unit is preferably assigned a number of interface modules of the type described above, which communicate with a number of assigned remote units or with their interface modules ,

0030Preferably, a central control computer is connected to one of the interface modules. This can be arranged externally, or form part of the master unit. The control computer is designed to coordinate the distribution of the essential communication signals within the distribution network, to evaluate the characteristic signal parameters and to control the digital units corresponding to the signal parameters. This makes it possible to control the remote units automatically within certain limits. For example, the digital units may be driven to appropriately handle the rushing essential communication signals as to the type of transmission method used. For example, this makes it possible to establish an essential communication in the simplex, duplex or semi-duplex method, depending on the received essential communication signal.

0031Likewise, means can already be provided in the master unit to localize the mobile terminal transmitting this, depending on the signal strengths received by the remote units and / or the duration of the essential communication signals. However, this can also be assigned to the central control computer.

0032In order to establish a communication between different essential communication bands, the central control computer is further preferably designed to drive the digital units to a frequency conversion between the frequency bands and / or a propagation delay of essential communication signals.

0033Embodiments of the invention will be explained in more detail with reference to a drawing. Showing:<dl id="dl0001" compact="compact"><dt>Fig. 1</dt><dd>schematically a remote unit with an interface module for transmitting essential communication signals, and</dd><dt>Fig. 2</dt><dd>schematically an antenna distribution system with a number of remote units.</dd></dl>

0034In <figref idref="f0001">Fig. 1</figref> schematically a remote unit 1 is shown, as it is part of a Antennenverteilsystems a mobile network. Remote Unit 1 is deployed inside buildings, tunnels, vehicles, stations, stadiums, etc. to enable radio communication of mobile terminals with a base station located outside the given location. In this case, a master unit 2 is provided, which is arranged in the vicinity of the given premises or location and connected to the base station. Via corresponding connecting lines (optical, electrical) or by radio, the master unit 2 communicates with a number of the remote units 1 shown. The remote units 1 send and receive communication signals and establish the actual radio connection to the mobile terminals.

0035The remote unit 1 includes not shown here further units to ensure communication between the master unit 2 and the mobile devices within the mobile network, an interface module 4, which allows the integration of communication on essential communication channels in the existing wireless network architecture.

0036For this purpose, the interface module 4 has a first interface 6 for analog data exchange with mobile terminals and a second interface 7 for analog and / or digital data exchange between the remote unit 1, the master unit 2 and further remote units. In other words, the remote unit 1 can be connected via the second interface 7 either to the master unit 1 or to further remote units 1. In the latter case, the remote units 1 are connected, for example via corresponding dividers in series or in a star shape to one another. In <figref idref="f0001">Fig. 1</figref> Such a constellation is indicated by the reference numeral 1 in parentheses. Between the two interfaces 6 and 7, the interface module 4 further comprises a signal path 9 in the downlink direction and a signal path 10 in the uplink direction. Via the signal path 10, signals received by the first analog interface 6 are routed to the second interface 7 and from there on to the master unit 2 or one or more further remote units. Along the signal path 9, signals received by the master unit 2 or one or more remote units at the second interface 7 are directed in the direction of the first analog interface 6 and transmitted from there by radio to mobile terminals. For receiving and transmitting radio signals, the first analog interface 6 is connected to a corresponding antenna unit, which is not shown graphically in the present case.

0037In the downlink signal path 9 and in the uplink signal path 10, a digital unit 11 is integrated, which has the primary task to digitize incoming communication signals to extract essential communication signals or hide remaining communication signals, pass on the essential communication signals and, before being transmitted to the analog interfaces 6, convert them analog again. The forwarding of the essential communication signals at the interface 7 to one or more remote units 1 or to the master unit 2 can take place analog or digital after conversion.

0038The interface module 4 is preceded by a so-called analog cross-band coupler 12, the communication channels of the mobile network separates from essential communication channels. The crossband coupler 12 may be part of the remote unit 1 or the interface module 4. Since the mobile are far separated from the essential channels, the requirements for the design of this analog filter are low.

0039The interface module 4 further has a communication unit 13 assigned to the digital unit 11. The communication unit 13 is designed to optionally process further processed data from the digital unit 11 and to supply via the second interface 7 of the master unit 2 or other remote units. Likewise, the communication unit 13 is designed to receive control data from the master unit 2 via the second interface 7 and to forward it to an activation to the digital unit 11.

0040The digital unit 11 is essentially given by a digital circuit 17, which in the present case is realized as a programmable integrated circuit (FPGA = Field Programmable Gate Array). In this digital circuit 17, the functions to be performed for the preparation of the digital data of the essential communication signals are implemented and controllable retrievable. Both the uplink signal path 10 and the downlink signal path 9 contain digital converter units 15, which transform incoming communication signals in the baseband. Between the second interface 7 and the digital unit 11 further digital converter units 16 are arranged according to the illustrated embodiment. These digital converter units 16 are required only when analog signals are to be transported within the distribution system. The digital unit 11 is trained to identify from the digitized communication signals, the essential communication signals, if necessary further treat and in uplink or in the downlink direction forward accordingly. The remaining communication signals are hidden and no longer considered by the interface module 4. To identify the essential communication signals their frequency and their transmission method is used. In particular, for essential communication enabled bands are arranged in a frequency space of less than 700 MHz. Further, the way of modulating the obtained communication signals can be used for identification. For example, many essential communication signals are amplitude modulated in a simple manner. Optionally, a frequency modulation is given. The type of clocking, a simplex, duplex or semi-duplex operation is taken into account by the digital unit 11 and used to identify the essential communication signal.

0041The digitally identified in the digital unit 11 essential communication signals can also be taken directly from the communication unit 13 and forwarded. These can also be modulated to increase the transmission rate, in particular, a phase or QAM modulation can be made.

0042The first analog interface 6 is further assigned a prefilter unit 18. This prefilter unit 18 has the task of effecting a coarse filtering of the frequency bands of essential communication signals in the uplink and downlink directions. Depending on the transmission method, the prefiltering can be realized as a filter in the frequency domain (FDD) or as a switch in the time domain (TDD). Since the bands of essential communication channels are still sufficiently spaced apart, a moderate analog frequency filter suffices in the frequency domain. After prefiltering, the interface module 4 operates independently of the duplex method with two separate transmission directions. For this purpose, in each case a separate signal path 9 in uplink and a separate signal path 10 in the downlink direction is formed. The number of uplink 9 ', 9 "and downlink paths 10', 10" depends on the number of essential frequency bands and / or their duplexing methods that are to be supported. In the exemplary embodiment, two FDD bands are shown by way of example.

0043The identification of the essential communication signals within the prefiltered frequency bands is analogously, as already stated, extremely expensive. Some of the channels allocated for essential communication only have a bandwidth in the kHz range. This actual identification therefore takes over the digital unit 11, which considers the digitized communication signals.

0044Between the first interface 7 and the digital unit 11 is in each case in the uplink signal path 10 and in the downlink signal path 9 an on or Off / on coupling unit 19 implemented. The communication unit 13 receives control data from the master unit 2 via these input / output units 19 and switches to the other signal parameter from the digital unit 11 in the uplink direction to the signal passed through. Furthermore, the digital baseband data can be input via the decoupling / decoupling unit 19 be decoupled. This happens preferably via a higher-order digital modulation method, such as QAM.

0045To amplify the received and to be transmitted signals is located between the digital unit 11 and the first analog interface 6, a number of amplifier units 20th Due to the low bandwidth of the essential communication signals and since these are already in the form of digital baseband data, a digital predistortion by means of a DPD amplifier 20 'can be used to amplify the signal to be transmitted. As a result, unwanted spurious emissions can be significantly reduced, which takes into account the extremely high Dynamikanfoderungen in adjacent bands.

0046The second interface 7 is associated with an electroopto converter 21, with which all signals are combined in the uplink direction and switched to a common optical waveguide 23. About the optical waveguide 23 is the remote unit 1 with the master unit 2 and possibly with other remote units in combination. To separate the received signals there converts a corresponding electroopto converter 22 incoming optical signals again into corresponding electrical signals. Conversely, electrical signals are converted into optical signals at the electroopto converter 22 of the master unit 2 in the downlink direction and transmitted via the optical waveguide 23 to the electroopto converter 21 of the remote unit 1 or further remote units. There incoming optical signals are converted into corresponding electrical signals and the downlink signal path 9 switched. The communication unit 13 receives control data therefrom via the coupling / decoupling unit 19 and optionally the digital baseband data for the digital unit 11. For this purpose, an interface 25 of a digital network, in particular Ethernet, implemented. Conversely, data exchange between the digital unit 11 of different remote units and the master unit 2 also takes place via this interface 25.

0047The digital unit 11 and the communication unit 13 are designed in particular to signal strength and transit time information, the nature of the essential communication signal and an address of the corresponding remote units 1, 1 ', ... aufzuschalten the common transmission signal and transmit to the master unit 2. Conversely, the communication unit 13 is designed to receive digital baseband data and control data of the master unit 2 and to control the digital unit 11 accordingly. In this case, it is provided, for example, to control the digital unit 11 at a time delay in the downlink direction in order to advantageously modify negative interference effects when transmitting the essential communication signals via a plurality of remote units. Also, the digital unit 11 can be controlled via the communication unit 13 in order to switch the remote unit 1 into a direct communication mode. In this case, essential communication signals obtained by the first analog interface 6 are amplified, if necessary offset in frequency or converted into another communication technology, sent back to the same analog interface 2 for re-transmission. As a result, the correspondingly controlled remote unit 1 becomes a relay station which improves on-site radio communication on essential communication channels and in particular allows communication to be established between different units using different essential transmission methods. In the uplink direction further two breaker switches are connected downstream of the amplifiers 20. These are controlled by the communication unit and prevent the emission of noise in the idle case.

0048The communication unit 13 does not necessarily communicate via the second interface 7. In particular, the communication with the communication unit 13 can also take place via a direct digital interface 25 'into a digital network such as Ethernet. A control computer can be connected directly to this interface. In other words, a local control center can be formed on site by connecting to the interface 25 'in order to quickly control in the event of a disaster, etc. via the various essential communication channels, using the architecture of the existing network of mobile communication.

0049In addition, the communication with the master unit 2 may preferably also take place via radio. Because of the low information density of the data to be transmitted, the second interface 7 can also be designed as a radio interface into a WLAN network.

0050At the crossband coupler 12, the communication signals of the mobile are separated from the essential signals. The communication signals of the mobile phone go through the actually intended remote unit 1 uninfluenced by the interface module 4. At the second interface 7 can now, as in<figref idref="f0001">Fig.1</figref> indicated, all transmission signals, ie the mobile network and the essential transmission channels, digital and analog signals to be merged, and forwarded via the common transmission line, here the optical waveguide 23, to the master unit 1 or to further remote units. Conversely, in the downlink direction, the corresponding incoming signals are separated there. Likewise, however, the interface module 4 may be equipped with a separate second interface 7, via which only the digital and / or analog signals of the essential communication channels or the communication unit 13 run.

0051The interface module 4 may be an integrable component of the remote unit 1 or a master unit 2. But it can also be designed as a separate additional module, which is connected via the corresponding lines to the remote unit 1 or the master unit 2. In the present case, it is connected to the second interface 7 and the cross-band coupler 12.

0052In <figref idref="f0002">Fig. 2</figref> schematically shown is an antenna distribution system 29, as it is used to establish communication within closed rooms, tunnels, vehicles, stadiums or in general in a radio shadow. For this purpose, the antenna distribution system 29 comprises a base station 30, which is connected by wire or by radio to a master unit 2. The master unit 2 is located outside the given location and exchanges data with remote units 1,1 ', 1 "located within the location. The exchange takes place here via a respective common optical waveguide. Within the given location, the communication between a mobile terminal 32 and the respective remote units 1 ', 1 ", 1'" takes place radio-bound.

0053The master unit 2 has to connect remote units 1,1 ', 1 "multiple electro-optic couplers 22 as they go to <figref idref="f0001">Fig. 1</figref> already described. In<figref idref="f0002">Fig. 2</figref> from top to bottom of these electro-optic couplers 22 are two remote units 1, 1 (2) in series, two remote units 1 ', 1' (2) star-shaped, and a remote unit 1 "alone connected 1,1 ', 1 "are connected to the master unit 2 via optical waveguides. In order to separate the signals from and to the individual remote units 1', 1", 1 ", respective optical dividers 35 are provided.

0054The antenna distribution system 29 shown makes it possible to establish radio communication of sufficient quality in locations that are hard to reach from the outside by radio. In the<figref idref="f0002">Fig. 2</figref> shown remote units 1,1 ', 1 "are all corresponding to an interface module 4 <figref idref="f0001">Fig. 1</figref> fitted. In this case, the uplink communication takes place in each case via the second interface 7, at which all transmission signals are combined or be separated, and transmitted together via an optical waveguide. In the electro-optic couplers 22 of the master unit 2 incoming communication signals are separated accordingly. In particular, the communication signals of the mobile network are separated and the usual further processing, transmission, amplification, etc. subjected. The transmission signals of the respective interface modules 4 from the remote units 1,1 ', 1 "are disconnected. For further processing and forwarding of these essential transmission signals are in the master unit 2 respectively, the Elektrooptpkopplern 22, 22 ', 22 "assigned, accordingly <figref idref="f0001">Fig. 1</figref> The communication with a central control computer 34 then takes place via local LAN interfaces 33, 33 ', 33 "assigned to the communication units 25. In particular, digital baseband data, including an IP address of the respective remote units 1, 1 ', 1 ", are exchanged. The control computer 34 can in particular have a landline connection.

0055Such an antenna distribution system 29 makes it possible to use the advantages of a modern network architecture for the transmission of essential communication signals.

LIST OF REFERENCE NUMBERS

0056<dl id="dl0002" compact="compact"><dt>1</dt><dd>Remote Unit</dd><dt>2</dt><dd>Master Unit</dd><dt>4</dt><dd>Interface Module</dd><dt>6</dt><dd>first analog interface</dd><dt>7</dt><dd>second analog interface</dd><dt>9</dt><dd>signal path</dd><dt>10</dt><dd>signal path</dd><dt>11</dt><dd>Digital unit</dd><dt>12</dt><dd>Cross-band coupler</dd><dt>13</dt><dd>communication unit</dd><dt>15</dt><dd>Digital converter units</dd><dt>16</dt><dd>Digital converter units</dd><dt>17</dt><dd>Digital Circuit (FPGA)</dd><dt>18</dt><dd>prefilter</dd><dt>19</dt><dd>An Add / Drop</dd><dt>20</dt><dd>amplifier unit</dd><dt>20 '</dt><dd>DPD amplifier</dd><dt>21</dt><dd>Elektrooptokoppler</dd><dt>22</dt><dd>Elektrooptokoppler</dd><dt>23</dt><dd>optical fiber</dd><dt>25</dt><dd>interface</dd><dt>25 '</dt><dd>interface</dd><dt>29</dt><dd>Antennenverteilsystem</dd><dt>30</dt><dd>base station</dd><dt>32</dt><dd>Mobile terminal</dd><dt>33</dt><dd>Local LAN connection</dd><dt>34</dt><dd>Central control computer with / without landline connection</dd><dt>35</dt><dd>Optical divider</dd></dl>