WO2021122110A1

WO2021122110A1 - Method for the fault monitoring of an antenna installation of a base station, monitoring system, testing device, base station and computer program therefor

Info

Publication number: WO2021122110A1
Application number: PCT/EP2020/084908
Authority: WO
Inventors: Amina Ayadi-Miessen; Klaus Dirksmeier; Jörn von Häfen
Original assignee: Hytera Mobilfunk Gmbh
Priority date: 2019-12-16
Filing date: 2020-12-07
Publication date: 2021-06-24
Also published as: DE102019134540A1; DE102019134540B4

Abstract

The invention relates to a method for the fault monitoring of an antenna installation (6) of a base station (8) of a digital radio network (5) by means of a testing device (7), which has a transmitter designed to transmit radio signals, the base station (8) being designed for communication with subscriber stations (9) of the radio network (5) by means of a number of frequency channels assigned to the radio network (5), and each frequency channel having a time-division multiplexing structure (39a, 39b) having successive time slots (37). The method comprises the following steps: a) selecting at least one time slot as a test-signal time slot by means of the testing device (7), b) transmitting a test signal (11) in the test-signal time slot by means of the testing device (7), the test signal (11) being transmitted by means of the transmitter (13) of the testing device (7) using an antenna (6a, 6b, 6c, 15) connected to the transmitter (13) of the testing device (7), c) receiving the test signal (11) by means of the base station (8), the test signal (11) being received using the antenna installation (6) of the base station (8), d) determining the reception quality of the test signal (11) received by means of the antenna installation (6) of the base station (8), e) detecting a fault of the antenna installation (6) depending on the reception quality of the received test signal (11). The invention further relates to an associated monitoring system (21), to a testing device (7), to a base station (8) and to a computer program.

Description

Method for fault monitoring of an antenna system of a base station, monitoring system, test device, base station and computer program for this

The invention relates to a method for fault monitoring of an antenna system egg ner base station of a digital radio network by means of a test device.

The invention also relates to a monitoring system for fault monitoring of an antenna system of a base station of a digital radio network as well as a test device and a base station of such a monitoring system.

The invention also relates to a computer program for performing a method of the type mentioned.

An antenna system within the meaning of the present application comprises at least one antenna. The antenna system can also include a line arrangement which connects the at least one antenna to other components of the base station. The line arrangement can include all the elements required for antenna coupling, e.g. lines, connecting elements, filters (e.g. input filters, duplex filters), duplexers and / or diplexers. The antenna system can in particular comprise a plurality of antennas. The antennas of the antenna system can each be designed as a transmitting antenna or as a receiving antenna or as a transmitting and receiving antenna (combined transmitting and receiving antenna).

A digital radio network within the meaning of the present application can in principle be any digital radio network that allows communication between base stations and Provides subscriber stations of the digital radio network. A digital radio network within the meaning of the present application can in particular be a digital mobile radio network. A digital radio network within the meaning of the present application can in particular be a digital trunked radio network.

A station within the meaning of the present application can be a base station or a subscriber station of the digital radio network.

An uplink frequency channel (uplink channel for short) is understood to mean a frequency channel on which a subscriber station transmits and a base station receives, while a downlink frequency channel (downlink channel for short) is understood to mean a frequency channel on which a base station transmits and a subscriber station receives.

In digital mobile radio networks, especially in digital trunked radio networks, there is the fundamental problem that the reliable provision of the services of the digital radio network requires error-free operation of the base stations of the radio network. This applies in particular to the antenna systems of the base stations.

The antenna system of a base station, in contrast to the other components of the base station, which are usually arranged in a so-called shelter (e.g. an operating room or a container, in particular a walk-in container or other protective housing), is usually in an exposed position brings, for example on an antenna mast. The antenna system is largely exposed to environmental influences without protection. In practice, it often happens that the antenna systems of base stations are damaged, e.g. by penetrating moisture, strong wind or vandalism, so that comprehensive radio coverage in the radio cell concerned and the provision of the associated services of the digital radio network are no longer available possible are. The spectrum of errors that occur in this process ranges from a gradual deterioration in the transmission and reception quality due to moisture damage to completely torn antennas and the associated sudden failure of the base station, for example caused by a storm. In order to ensure reliable operation of the digital radio network and its base stations, it is therefore necessary to monitor the antenna systems of the base stations, ie it is necessary to monitor the antenna systems of the base stations for possible errors in the antenna system .

From the prior art it is known to measure a voltage standing wave ratio (VSWR), return loss or other variables that indicate the quality of the line adaptation on the antenna line for fault monitoring of antennas ( Reflection measurement) and to draw conclusions about errors in the antenna or the connection to the antenna from the deterioration in the adaptation.

A method and an associated device for measuring the VSWR at an antenna to a base station are known, for example, from US Pat. No. 6,313,644 B1.

Such a method for error monitoring of the antenna systems of Basisstatio NEN based on reflection measurements, z. Based on a measurement of the VSWR or a similar adaptation measurement, however, are associated with a number of disadvantages. In particular, such methods allow only a low level of accuracy in monitoring, since the accuracy is limited, for example, by the attenuation of the connecting lines. Gradual changes in the performance of the antenna system, which can be caused, for example, by the penetration of water into plugs, sockets and / or other connecting elements, cannot be reliably detected with the help of VSWR-based or similar measurements. A further disadvantage of such methods known from the prior art arises in the fault monitoring of the antenna systems of base stations in that pure receiving antennas, i.e. antennas of the base stations exclusively intended for signal reception, cannot be monitored in this way.

Based on this, it is the object of the present invention to provide a possibility for improved error monitoring of the antenna systems of base stations, which in particular allows monitoring with greater accuracy. This object is achieved by a method for fault monitoring of an antenna system of a base station of a digital radio network by means of a test device, which has the features of claim 1.

The test device has a transmitter set up for the transmission of radio signals. The base station is directed for communication with subscriber stations of the radio network via a number of frequency channels assigned to the radio network. Each frequency channel has a time division multiplex structure, i. H. a TDMA structure, with time slots that follow one another.

According to the invention, the method has the following steps: a) the test device selects at least one time slot as the test signal time slot, b) the test device transmits a test signal in the test signal time slot, the test signal being transmitted to the transmitter via the transmitter of the test device the antenna connected to the test device is transmitted, c) receiving the test signal by the base station, the test signal being received via the antenna system of the base station, d) determining a reception quality of the test signal received by means of the antenna system of the base station, e) detecting a fault in the antenna system as a function the reception quality of the received test signal.

As an alternative or in addition to the detection of errors, the fault monitoring of the antenna system can also include a determination of the performance of the antenna system, in particular the performance of the at least one antenna and / or the line arrangement. As an alternative or in addition to the detection of a fault in the antenna system in step e) of the method, a performance of the antenna system can accordingly be determined as a function of the reception quality in step e) of the method. It is therefore proposed that the fault monitoring of the antenna system be carried out by means of a test device, the test device being set up to transmit a test signal via at least one of the frequency channels assigned to the radio network. For this purpose, the test device has a transmitter which is connected to an antenna.

The invention is based on the knowledge that it offers advantages to transmit such a test signal by means of the test device via the air interface to the base station. A particular advantage of the invention is that the reception of the test signal by the base station and the determination of the reception quality of the received test signal provides a basis for very precise error monitoring of the antenna system of the base station. For example, even slight deterioration in reception quality can be detected and conclusions can already be drawn on this basis about a fault in the antenna system, e.g. caused by urgent water. If an unexpected deterioration in the reception quality is detected, a warning or an alarm can be generated as an output, for example.

In an advantageous development of the invention it is provided that the time slot which is selected as the test signal time slot in step a) and is used in step b) for transmitting the test signal is a time slot in the time division multiplex structure is not intended for communication between different stations of the digital radio network.

It is therefore proposed that the test signal be transmitted in a time slot (ie during the duration of a time slot) of the time division multiplex structure which is not intended for communication between different stations, ie not for communication between different subscriber stations and not for communication between subscriber stations and base stations and not intended for communication between different base stations. Communication between different stations does not normally take place in such a time slot. Such a time slot can e.g. B. be a time slot in the time division multiplex structure for a self-test of the subscriber stations and / or the Base stations is provided. Such a self-test can be, for example, a self-test of the transmitters and / or the receivers and / or the transceivers of the stations. Such timeslots that are not intended for communication between various stations of the digital radio network can be specified in the time division multiplex structure of the radio network in particular by a dedicated logic channel for this purpose, z. B. in the form of a self-test channel.

The inventive transmission of a test signal in such a time slot, which is not intended for communication between different stations, offers the advantage that error monitoring of the antenna system of the base station is possible completely independently of the existing voice and / or data traffic in the digital radio network . This means that reliable and interference-free error monitoring of the antenna system is even possible when the digital radio network is at full capacity, i.e. even when all traffic channels in the digital radio network are busy. The method according to the invention accordingly offers the advantage that the functionality of the digital radio network is in no way impaired by the error monitoring.

In a further advantageous development of the invention it is provided that at least one of the frequency channels has a linearization time slot which is provided in the time division multiplex structure so that the subscriber stations can linearize their transmitters in this time slot. The time slot that is selected as the test signal time slot in step a) and is used in step b) for transmitting the test signal is such a linearization time slot.

It is therefore proposed that a linearization time slot be selected as the test signal time slot and used for the transmission of the test signal. Such a development of the invention is based on the knowledge that it is possible and offers a number of advantages to transmit a test signal by means of the test device in a linearization time slot (ie during the duration of such a time slot). Such a linearization time slot is provided in the time multiplex structure of some digital radio networks, in particular digital mobile radio networks and digital trunked radio networks, so that the subscriber stations in this Time slot can perform a linearization of their transmitters. Such a linearization can in particular be an amplifier linearization.

With such a linearization, the respective subscriber station can carry out a type of self-test of its transmitter and measure undesired deviations of an actual transmission signal from a target transmission signal, which can be caused by non-linear distortions. Correction signals can be derived from the measured deviations in order to compensate for the non-linear distortions and in this way to linearize the transmitter or amplifier. Since the subscriber stations of the radio network should have the opportunity to linearize their transmitters, such linearization time slots can be provided in particular on those frequency channels of the radio network that are provided for communication from the subscriber station to the base station, ie on the frees intended for the uplink frequency channels.

A linearization time slot is therefore an example of a time slot of the type explained above that is not provided in the time division multiplex structure for communication between different stations (base station or subscriber station) of the digital radio network. Communication between subscriber stations or between subscriber station and base station does not normally take place in the linearization time slot.

Such linearization time slots can be specified in the time division multiplex structure of the radio network, in particular by a logical channel in the form of a linearization channel.

Such a linearization channel, whose time slots serve as linearization time slots for the linearization of the transmitters of the subscriber stations, is provided, for example, in digital trunked radio networks according to the TETRA standard and is referred to in the TETRA standard as a common linearization channel (CLCH). The CLCH of the TETRA standard is a logical channel that is provided on the uplink frequency channels of the TETRA trunked radio networks. The TETRA standard provides that each frequency channel has a time division multiplex structure (TDMA structure), the one Includes division of time into frames. Each frame of the time division multiplex structure consists of four time slots. 18 consecutive frames are combined into a so-called multiframe. In the time division multiplex structure of the TETRA standard, one of the four time slots in every 18th frame, the so-called control frame, of each multiframe of an uplink frequency channel is provided as the linearization time slot, ie as the time slot assigned to the CLCH the first of the two sub-time slots (subslots) is determined by the CLCH.

In a further advantageous development of the invention it is provided that the time slot, which is selected in step a) as the test signal time slot and is used in step b) for transmitting the test signal, is a time slot that is one in the time multiplex structure Traffic Channel is assigned.

It is therefore proposed that the test signal be transmitted in a time slot that is provided for the transmission of useful data, e.g. B. for a transmission of voice data and / or other useful data. Such a development of the invention offers the advantage that unused transmission capacities of the digital radio network can be used for transmitting the test signal. He inventive method can in this way, for. B. can also be used in digital radio networks in whose time-division multiplex structure no linearization time slot of the type explained above is provided and no other time slot is provided that is not intended for communication between different stations in the type explained above.

In a further advantageous development of the invention, it is provided that the test device in step a) of the method is registered like a subscriber station in a radio cell of the digital radio network assigned to the base station. The time slot selected in step a) as the test signal time slot and used in step b) for transmitting the test signal is an assigned time slot that the base station assigns to the registered test device for the transmission of radio signals.

Logging into a radio cell is understood to be the usual process in digital radio networks in which the subscriber stations determine themselves Radio cell registered, ie registered (e.g. "Registration" in the TETRA standard). Such a form of access to the transmission resources, in which the base station assigns the respective registered subscriber station a time slot for uplink transmissions of the subscriber station, is provided in many digital radio networks, e.g. B. in digital radio networks according to the TETRA standard.

The aforementioned development of the invention thus provides that the test device behaves when selecting the time slot for transmitting the test signal like a subscriber station when transmitting useful data. Such a development of the invention offers the advantage that it can be implemented particularly easily, since only a standard-compliant access of a subscriber station to the transmission resources has to be implemented. It can, for. B. can be used on existing implementations for subscriber stations.

In a further advantageous development of the invention it is provided that the test device is booked into the radio cell assigned to the base station with a priority that is lower than the priority of the other subscriber stations registered in the radio cell.

Such a development of the invention offers the advantage that impairments of the voice and data traffic of the subscriber stations in the digital radio network, which can arise from the logging in of the test device and the transmission of the test signal, can largely be avoided in this way. This is achieved in that the subscriber stations can access the time slots of the time division multiplex structure (i.e. the transmission resources of the radio network) with a higher priority than the test device. Such avoidance of impairment of voice and data traffic in digital trunked radio networks that are used by authorities and security organizations, and especially when the radio network is heavily used, is of particular importance.

In a further advantageous development of the invention it is provided that in step a) of the method the test device listens to at least one of the frequency channels and thereby determines at least one free time slot that plex structure is assigned to a traffic channel and is currently not being used for transmitting radio signals. The test device selects such a free time slot in step a) as the test signal time slot and thus transmits the test signal in this free time slot in step b).

Listening to the frequency channel and determining the free time slot can be done, for. B. be done by a carrier sensing. Alternatively or in addition, it is also conceivable that the test device to determine the free time slot listens to a signaling channel (control channel) on which information about the occupancy of the time slots is transmitted.

Such a development of the invention, in which the test device determines a free time slot by listening to a frequency channel, offers the advantage that the test device does not need to be logged in.

In a further advantageous development of the invention it is provided that the test device has its own antenna which is connected to the transmitter of the test device. The test signal is transmitted in step b) via the antenna of the test device.

Such a development of the invention offers the advantage that all antennas of the antenna system of the base station can be reliably monitored in a simple manner, since none of the antennas of the antenna system of the base station have to be used for the transmission of the test signal. This also enables reliable and precise monitoring of antenna systems that only have a single antenna in the form of a combined transmitting and receiving antenna. In addition, fault monitoring of the antenna system of the base station can be retrofitted particularly easily in this way, since no wired connection between the test device and the base station is required.

In a further advantageous development of the invention it is provided that the antenna system has a plurality of antennas and the transmitter of the test device is connected to at least one first antenna of the antenna system of the Base station, which is designed as a transmitting antenna or as a receiving antenna or as a combined transmitting and receiving antenna. The test signal is transmitted via the first antenna in step b). In step b) the test signal is received via at least one second antenna of the antenna system of the base station, which is different from the first antenna and is designed as a receiving antenna or as a combined transmitting and receiving antenna.

It is therefore proposed that the transmitter of the test device be coupled to an antenna of the base station for transmitting the test signal. The transmitter of the test device can, for. B. be connected to the antenna of the antenna system of the base station via an antenna coupler.

Such a development of the invention offers the advantage that the test device does not have to have its own antenna, but can transmit the test signal via an antenna of the base station, so that cost advantages arise. Such a development is also advantageous because the accuracy of the error monitoring can be impaired by quasi-random fluctuations in the reception quality (Fa ding) of the test signal. If the test device's own antenna is used to transmit the test signal, such random fluctuations can be largely limited, e.g. B. can be achieved by an optimal positioning tion of the antenna of the test device on the transmission mast of the base station. If, on the other hand, an antenna of the base station is used, which is generally optimally positioned on the transmission mast anyway, there is no need for an additional antenna that is laborious to position.

In a further advantageous development of the invention it is provided that the antenna system has a plurality of antennas set up for the reception of radio signals, each of which is designed as a receiving antenna or as a combined transmitting and receiving antenna, wherein in step c) the test signal over the majority for reception antennas set up by radio signals are received and in step d) for each of the antennas set up for the reception of radio signals an antenna-related reception quality of the test signal received by means of the respective antenna is determined and in step e) an antenna of the antenna system affected by an error is recognized by comparing the antenna-related reception qualities.

Such a development of the invention offers the advantage that it can be determined which antenna of the antenna system is affected by a fault. This allows errors that occur to be eliminated particularly quickly and effectively.

For example, for this purpose, the antenna-related reception quality can be used to evaluate which antennas are affected by unusually poor reception quality. If this applies to all antennas of the antenna system via which the test signal was received, an error can be assumed for the antenna via which the test signal was transmitted. If, on the other hand, this only applies to one of the antennas, a fault in the antenna concerned can be assumed.

It is advantageous if the test device transmits the test signal via a transmission antenna of the antenna system of the base station (i.e. the transmitter of the test device is connected to a transmission antenna of the base station). In this way it is possible, by comparing the antenna-related reception qualities in the above-mentioned manner, to also reliably and securely detect errors in the transmitting antenna.

In a further advantageous development of the invention it is provided that in step d) an antenna-related reception quality of the test signal received by means of the respective antenna is determined for at least one antenna of the antenna system set up for the reception of radio signals and in step e) one of an error The affected antenna of the antenna system is recognized as a function of the antenna-related reception quality and a result of a reflection measurement of at least one antenna of the antenna system. It is therefore proposed that the previously explained detection of a fault in the antenna system on the basis of the reception quality of the test signal be combined with a reflection measurement of at least one antenna of the antenna system. Such a reflection measurement can, for. B. a measurement of a standing wave ratio (Voltage Standing Wave Ratio, VSWR for short) and / or a return damping (return loess) and / or other variables that indicate the quality of the line adjustment.

Such a development of the invention offers the advantage that it provides a complete and reliable monitoring of the antenna system of the base station z. B. allowed even if the antenna system has only a single transmitting antenna and a few receiving antenna. In this case, the transmitter of the test device can be connected to the transmitting antenna of the base station and the test signal can be transmitted via the transmitting antenna. In addition, the test device can carry out a reflection measurement on the transmitting antenna. By evaluating the reception quality of the test signal received via the receiving antenna on the one hand and evaluating the reflection measurement at the transmitting antenna on the other hand, it can be reliably determined which of the two antennas is affected by an error.

In a further advantageous development of the invention it is provided that in step a) the test device determines a reception quality, in particular a reception power, of a downlink signal transmitted by the base station and received by the test device.

Such developments of the invention, in which the test device determines a reception quality of a downlink signal, offer the advantage that error monitoring of the antenna system of the base station in the downlink is made possible on this basis. As a result, pure transmit antennas of the antenna system and the associated connecting lines can be monitored, ie those antennas of the antenna system and the associated connecting lines that the base station uses exclusively for transmitting and not for receiving can be monitored. In a further advantageous development of the invention it is provided that in step b) the test device transmits a test message with the test signal which can be decoded by the base station. The test message contains information about a reception quality, in particular a reception power, a downlink signal transmitted by the base station and received by the test device.

It is therefore proposed that the test device transmit a test message with test data, the test data containing information about the reception quality of a downlink signal received by the test device. Such a development of the invention offers the advantage that error monitoring of the transmitting antennas of the base station can be carried out on this basis (see above).

As an alternative or in addition to this, the test message can contain, as test data, an identifier of the test device and / or an identifier of the base station and / or information about a transmission power of the test signal transmitted by the test device.

Such developments of the invention offer the advantage that the possible uses of the method according to the invention can be expanded through the test data contained in the test message. By transmitting an identifier of the test device and / or an identifier of the base station, an unambiguous assignment of the base station to be monitored and / or the test device monitoring the base station can be ensured in an advantageous manner. This is particularly advantageous when a single test device monitors a number of base stations and / or a number of test devices are used to monitor errors in one or more base stations. A transmission of the transmission power of the test signal transmitted by the test device is advantageous because on this basis, for example, an expected reception quality and / or a reference value of the reception quality is determined and conclusions can be drawn about errors in the antenna system from deviations of the determined reception quality from the expected reception quality or the reference value can be In a further advantageous development of the invention, it is provided that the time slot that the test device selects in step a) as the test signal time slot is a time slot that is repeated at time intervals specified by the time-division multiplex structure, with at least steps b) , b) and d) are executed for each repetition or at least for some of the repetitions of the time slot.

Such a time slot can be, for example, a linearization time slot of the type explained above.

Such a repetition of a time slot, e.g. B. a linearization time slot can result, for example, from the repetition of a frame comprising several time slots and / or from the repetition of a multi-frame comprising several frames. In the case of the time-division multiplex structure according to the TETRA standard, the CLCH, whose assigned time slot represents a linearization time slot within the meaning of the present invention, is repeated, for example, with every multi-frame, namely in the so-called control frame (the 18th frame ) of the multiframe, the exact position of the linearization time slot of the CLCH according to the TETRA standard varying between the first time slot and the fourth time slot of the control frame.

It is therefore proposed that at least the inventive transmission of the test signal in the test signal time slot by the test device, the reception of the test signal by the base station and the determination of the reception quality of the test signal received by the base station for each repetition or at least for some of the repetitions of the time slot selected as the test signal time slot, e.g. B. the linearization time slot can be performed. It is conceivable, for example, that the steps mentioned are carried out at every repetition or every second repetition or every fourth repetition or every nth repetition of the time slot. In the case of the previously explained linearization time slot of the TETRA standard, this would mean that the steps mentioned can be carried out, for example, in every multiframe, in every second multiframe, in every fourth multiframe or in every nth multiframe. It is also conceivable that steps a) and / or e) are carried out in the manner mentioned for each repetition or at least for some of the repetitions of the time slot.

Such developments of the invention, in which the time slot selected as the test signal time slot is repeated at time intervals and the cited steps of the method according to the invention are carried out with each repetition or with at least some of the repetitions, offer the advantage that they allow continuous error monitoring of the Enable antenna installation. Furthermore, it is possible in this way to determine a time course of the reception quality from which a possible deterioration in the reception quality can be recognized. On this basis, errors in the antenna system can be detected even in the event of a severe deterioration in reception quality.

In a further advantageous development of the invention it is provided that in step a) the test device determines one of the frequency channels as the target channel for the transmission of the test signal and selects the test signal time slot on the target channel and in step b) the test device selects the test signal in the Transmits test signal time slot on the target channel.

The target channel is the frequency channel that is used for transmitting the test signal by the test device. Advantageously, this can be the uplink frequency channel of the base station to be monitored, ie that frequency channel which is intended for signal transmission from subscriber stations to the base station to be monitored, since this frequency channel can be received by the base station to be monitored without further changes the base station are required. The test device can in particular automatically determine one of the frequency channels as the target channel.

After the target channel has been determined, the test signal time slot is selected on the target channel, ie the position of the time slot that is to serve as the test signal time slot is determined within the time-division multiplex structure of the target channel. Such a development of the invention, in which the test device determines one of the frequency channels as the target channel, offers the advantage that the test device can also be used flexibly and without manual individual configuration of a frequency channel if the digital radio network has a plurality of frequency channels assigned.

In a further advantageous development of the invention it is provided that the frequency channels comprise a number of uplink frequency channels and a number of downlink frequency channels, the test signal time slot selected in step a) being a time slot of an associated uplink frequency channel and the test signal in Step b) is transmitted in the test signal time slot on the associated uplink frequency channel, and / or the target channel is an uplink frequency channel.

In such a development of the invention, the frequency channels assigned to the radio network are divided into uplink channels and downlink channels, i.e. the radio network uses a frequency division duplex (FDD) as a duplex method. Provision is made for the test signal to be transmitted on an uplink channel.

Such a development of the invention offers the advantage that, in the error-free case, it allows the base station to receive the test signal reliably and largely without loss, without modifications to the base station being required for this purpose. The reason for this is that the reception filters or reception branches of the duplex filters of the base station are in any case set up for signal reception on the uplink channel. For reliable and precise error monitoring it is therefore only necessary that the base station listens to the uplink channel on which the test signal is transmitted for the duration of the linearization time slot.

In a further advantageous development of the invention it is provided that in step a) the test device determines the target channel in that the test device has a plurality of downlink frequency channels, in particular the downlink frequency. quenzkanäle of a predetermined list of frequency channels, listens and selects an uplink frequency channel, which is assigned to one of the monitored downlink frequency channels, as the target channel. The uplink frequency channel selected as the target channel can in particular be the uplink frequency channel that is assigned to the downlink frequency channel with the greatest signal strength.

It is therefore proposed that the test device scan the downlink frequency channels assigned to the radio network and, on this basis, select an uplink frequency channel as the target channel. The signal strength of the monitored downlink frequency channels can be determined, for example, in the form of a received power and / or in the form of an RSSI. Selecting that uplink frequency channel that is assigned to the downlink frequency channel with the greatest signal strength can be particularly useful if the test device is arranged in the immediate vicinity of the base station to be monitored. The reason for this is that in this case the frequency channel with the greatest signal strength corresponds with a high degree of probability to the frequency channel on which the base station to be monitored transmits. This provides a simple way of determining the carrier (carrier) used by the base station to be monitored, i. H. to determine the pair of frequency channels used by the base station to be monitored (uplink and downlink frequency channel), and on this basis to select the target channel.

In a further advantageous development of the invention it is provided that in step a) the test device for selecting the test signal time slot and / or for determining the time slot that is not provided in the time division multiplex structure for communication between different stations of the digital radio network, and / or to determine the linearization time slot listens to at least one signaling channel of the radio network and decodes signaling information that is transmitted by the base station on the signaling channel.

In digital radio networks, it is common for base stations to display the respective position of certain time slots within the multiplex structure in the form of signaling information on signaling channels. This also applies to the respective position of certain time slots that are suitable as test signal time slots, e.g. B. the Be the position of a linearization time slot and / or the position of another time slot that is not intended for communication between different stations. This fact is used in the aforementioned further development of the invention in order to determine the time position of the time slot that is to be selected as the test signal time slot within the multiplex structure. Listening to the signaling channel and decoding the signaling information transmitted on the signaling channel represent a simple and reliable way of using the test device to determine a time slot that is suitable as a test signal time slot.

In a further advantageous development of the invention it is provided that the digital radio network is a digital trunked radio network, in particular a digital trunked radio network according to the TETRA standard.

Such a development of the invention offers the advantage that the invention can be used for digital trunked radio networks and in particular for digital trunked radio networks based on the widespread TETRA standard. Reliable error monitoring of the antenna systems of base stations is of particular importance in such networks, since these networks are often used by authorities and organizations with security tasks (BOS).

Another advantageous development of the invention provides that the digital radio network and the time division multiplex structure correspond to the TETRA standard and the test signal time slot is a linearization time slot that is assigned to a common linearization channel (CLCH) of the TETRA standard.

A common linearization channel (CLCH) is also understood to mean a common linearization channel, QAM (CLCH-Q).

In a further advantageous development of the invention it is provided that the digital radio network and the time division multiplex structure correspond to the TETRA standard and in step a) the test device for determining the target channel and / or for determining the linearization time slot listens to a main control channel (MCCH) on at least one frequency channel and decodes signaling information transmitted by the base station on the main control channel (MCCH) and / or - decodes signaling information sent by the base station on an access assignment channel (AACH ) are transmitted.

An Access Assignment Channel (AACH) in the sense of the present application can also be an Access Assignment Channel, QAM (AACH-Q).

The signaling information that is transmitted by the base station on the Main Control Channel (MCCH) can in particular indicate a network operator of the radio network. Such signaling information that is transmitted from the base station on the MCCH can be, for example, a Mobile Country Code (MCC) and / or a Mobile Network Code (MNC). The signaling information that is transmitted by the base station on the Access Assignment Channel (AACH) can in particular indicate a linearization time slot, in particular in the form of a time slot of a common linearization channel (CLCH).

Such a development of the invention, in which the test device listens to the MCCH and decodes signaling information, offers the advantage that it facilitates reliable identification of the base station to be monitored, the associated frequency channel and the associated physical channel.

Such a development of the invention, in which the test device decodes signaling information that is transmitted from the base station on an AACH to who, offers the advantage that a fast and error-free determination of a time slot suitable as a test signal time slot, e.g. B. a linearization time slot is made possible.

In a further advantageous development of the invention it is provided that an error is recognized as the output in step e) if the reception quality and / or a variable derived from the reception quality fulfills a predefined condition, in particular falls below a predefined threshold value of the reception quality. In a further advantageous development of the invention it is provided that an output is generated in step e) which is used to monitor errors in the antenna system.

In a further advantageous development of the invention it is provided that in step e) a warning and / or an alarm is generated as output if the reception quality and / or a variable derived from the reception quality fulfills a predefined condition, in particular falls below a predefined threshold value for the reception quality .

Another advantageous development of the invention provides that a warning is generated as the output in step e) if the reception quality and / or the variable derived from the reception quality meets a first condition, in particular falls below a predetermined first threshold value for the reception quality, and / or An alarm is generated when the reception quality and / or the variable derived from the reception quality meets a second condition, in particular falls below a predetermined second threshold value for the reception quality, the second threshold value for the reception quality being less than the first threshold value for the reception quality.

A variable derived from the reception quality can be, for example, an evaluation of a time course of the reception quality, in particular an average value of the reception quality. The reception quality can be measured, for example, in the form of a reception power and / or in the form of an RSSI.

It is conceivable, for example, that the threshold values for the reception quality are set in relation to a reference value for the reception quality. The reference value of the reception quality can be, for example, a value of the reception quality that is expected in the error-free case, for example the reception power and / or the RSSI. Furthermore, it is advantageously possible that at least one threshold value of a deviation is determined and an error is detected in the manner explained above and / or a warning and / or an alarm is generated if the deviation of the reception quality exceeds the threshold value of the Deviation exceeds the amount.

For example, it is possible that the threshold value of the reception quality is determined as a function of the reference value of the reception quality and the threshold value of the deviation. For example, the first threshold value of the reception quality can be determined as a function of the reference value of the reception quality and a first threshold value of the deviation and the second threshold value of the reception quality can be determined as a function of the reference value of the reception quality and a second threshold value of the deviation.

It is conceivable, for example, that a warning is generated if the reception quality of the reception power or a variable derived therefrom (e.g. a time average) falls below the reference value of the reception quality by more than the first threshold value of the deviation. As an alternative or in addition to this, it is conceivable, for example, that an alarm is generated if the reception quality and / or the variable derived therefrom fall below the reference value of the reception quality by more than the second threshold value of the deviation.

The first threshold value of the deviation can be e.g. 3 dB, the second threshold value of the deviation can be e.g. 10 dB.

Such developments of the invention, in which an error is recognized as a function of a predetermined condition and / or a warning and / or an alarm are generated, advantageously allow a quick and reliable detection and display of an error in the antenna system, so that a quick and effective troubleshooting is possible. In a further advantageous development of the invention it is provided that the threshold value of the reception quality and / or a reference value of the reception quality are determined from the reception quality of one or more received test signals.

It is advantageously possible, for example, for the threshold value and / or the reference value to be determined from the reception quality of one or more received test signals which are received by the base station in a state of the antenna system of the base station that is known to be error-free. The threshold value and / or the reference value can accordingly advantageously be determined from the reception quality of one or more received test signals when the antenna system of the base station is in a state known to be error-free. For example, the threshold value and / or the reference value can be determined from the reception quality of the test signals immediately after the base station has been put into operation, since an error-free state of the antenna system can be expected immediately after the base station has been put into operation.

The threshold value can advantageously be determined from the reception quality of one or more received test signals, for example by determining a reference value for the reception quality from the reception quality of one or more received test signals. Such a reference value for the reception quality can be, for example, a value for the reception quality that is determined in the manner explained above in a state of the antenna system of the base station that is known to be error-free. The threshold value of the reception quality can be determined on the basis of the reference value of the reception quality, for example, in that a threshold value of the deviation is subtracted from the reference value, as explained above.

Such developments of the invention, in which the threshold value of the received power and / or the reference value of the received power are determined from the reception quality of one or more received test signals, offer the advantage that the threshold value and / or the reference value are determined simply, automatically and reliably can. In a further advantageous development of the invention it is provided that at least steps b), c) and d) are repeated at time intervals and in step e) an evaluation of a time profile of the reception quality of the test signals received by the base station is generated. The output is generated depending on the evaluation of the time course. As an alternative or in addition to generating the output as a function of the course over time, a fault in the antenna system can be detected as a function of the course over time and / or a performance of the antenna system can be determined as a function of the course over time.

Such developments of the invention offer the advantages that permanent monitoring of the antenna system is made possible and also gradual changes in the reception quality can be determined by evaluating the time profile and creeping error profiles of the antenna system can also be recognized on this basis.

In a further advantageous development of the invention it is provided that the evaluation of the time profile includes a mean value, in particular a sliding mean value, and / or a gradient of the reception quality.

Such a mean value and / or such a gradient of the reception quality are examples of variables derived from the reception quality in the sense explained above. In such developments of the invention it can thus be provided that the individual values of the reception quality determined over time are fed to a filter, in particular a low-pass filter, in order to determine an average value, in particular a moving average value.

Such developments of the invention offer the advantage that they allow an evaluation of the time course of the reception quality with comparatively simple means and at the same time enable reliable conclusions to be drawn about errors in the antenna system from a change in the reception quality over time.

In a further advantageous development of the invention it is provided that an error classification is carried out in step e) by evaluating the The time course of the reception quality is compared with stored comparison data and a type of error is determined as a function of this comparison, and an output is generated which contains information about the type of error determined.

Such comparison data can be, for example, stored comparison time curves, i.e. stored time curves of the reception quality used for comparison purposes and / or evaluations generated therefrom that are characteristic of certain types of errors. For example, an abrupt deterioration in reception quality can be characteristic of a torn antenna and a gradual deterioration in reception quality can be characteristic of moisture damage in the antenna system. By making a comparison with the stored comparison data, it is therefore possible, in addition to the mere fact that there is a fault in the antenna system, to also determine a type of fault. Examples of the type of defect are the types of defects “torn off antenna” or “ingress of moisture”.

Such developments of the invention offer the advantage that they offer an improved fault diagnosis, on the basis of which a fast and effective elimination of the fault is possible.

Another advantageous development of the invention provides that the test device repeats the transmission of the test signal at time intervals and the test device listens to at least one signaling channel of the radio network, in particular a main control channel (MCCFI) of the TETRA standard, and receives downlink signals in the process that are transmitted by the base station on the signaling channel, the test device terminating the repeated transmission of the test signal when the test device can no longer receive the downlink signals on the signaling channel that has been heard and / or when the received power of the received on the signaling channel Downlink signals fall below a predetermined threshold value for the received power.

Such developments of the invention offer the advantage that the transmission of the test signals can be automatically interrupted or finally ended if the base station has been deactivated or if the physical channel used by the base station has changed.

The object mentioned at the beginning is also achieved by a monitoring system for fault monitoring of an antenna system of a base station of a digi tal radio network with the features of claim 26. The monitoring system according to the invention has a base station and a test device of the type explained above and is for performing a method set up of the type explained above.

In an advantageous development of the invention, the monitoring system has a processing device which is connected to a number of base stations in the digital radio network. The processing device is set up to carry out step e) of the method explained above. As an alternative to this, the processing device can be set up to carry out steps d) and e) of the method explained above.

It is therefore proposed that the monitoring system have a processing device which is set up to detect a fault in the antenna system as a function of the reception quality. As an alternative or in addition to this, the processing device can also be set up to generate an output that is used for error monitoring of the antenna system as a function of the reception quality and / or to determine a performance of the antenna system as a function of the reception quality. In addition, the processing device can also be set up to determine the reception quality of the test signal received by means of the antenna system of the base station.

Such a processing device can be designed as a computer that is part of the base station or as an external computer that is connected to one or more base stations. Such a processing device can, for example, also be designed as a server that is connected to one or more base stations, in particular as a central server that is connected to a plurality of base stations in the digital radio network. Such a server can in particular be designed as a database server that is set up for determining, processing, Monitoring and / or outputting the results of the method according to the invention for error monitoring. The output can contain, for example, a visualization of the reception quality, variables derived therefrom, or other results of the error monitoring.

In a further advantageous development of the invention it is provided that the test device and / or the processing device and / or the monitoring system are set up for fault monitoring of a plurality of antenna systems belonging to a plurality of base stations of the digital radio network.

Such a development of the invention offers the advantage that a plurality of base stations can be monitored from a central point, so that the installation effort required for the monitoring and the costs associated therewith can be reduced.

The object mentioned at the beginning is also achieved by a test device of the type explained above for fault monitoring of an antenna system of a base station of a digital radio network.

In an advantageous development of the invention it is provided that the test device is set up to be connected to an interface of the base station, in particular to an alarm output of the base station, and by an activation signal generated by the base station and received by the test device via the interface to be activated and / or to be deactivated by a deactivation signal generated by the base station and received by the test device via the interface.

Such a development offers the advantage that the control of the test device can be integrated into the control of the base station and in this way the control of the test device can be simplified.

In a further advantageous development of the invention it is provided that the test device is designed as a modified subscriber station of the digital radio network. Such a development of the invention offers the advantages that on the one hand it enables simple and therefore inexpensive provision of the test device and on the other hand it ensures that the test device is set up for communication, in particular for data transmission, in the digital radio network.

The object mentioned at the beginning is also achieved by a base station of the type explained above for fault monitoring of an antenna system of the base station.

The object mentioned at the beginning is also achieved by a computer program with program code means which is set up to carry out a method of the type explained above when the computer program is executed on at least one computer. The computer can be a computer of a monitoring system of the type explained above and / or a computer of a test device of the type explained above and / or a computer of a base station of the type explained above and / or a computer of a processing device of a monitoring system of the type explained above be.

The computer program can in particular be set up to carry out the method of the type explained above when the computer program is executed on a plurality of computers, for example on a computer of a test facility and a computer of a base station or on a computer of a test facility and a Computer of a base station and a computer of a processing device of the type explained above.

Compared to the prior art, the invention offers a number of advantages in fault monitoring of the antenna systems of base stations:

An individual frequency configuration of the test device is not required, since the test device can automatically recognize which frequency channels the base station to be monitored is using by scanning the frequency channels. In this way, it is also advantageously possible for the test device to react automatically to changes in the frequency channels used by the base station to be monitored. Since the test device can be a device based on a subscriber station of the digital radio network, it is possible in a simple manner to provide a multiband-capable test device. This advantageously eliminates the need to provide different hardware variants of the test device for different frequency bands available.

Another advantage of the invention is that it is not necessary to occupy a traffic channel of the digital radio network for error monitoring. Accordingly, no interface is required for occupying a traffic channel between the test device and the base station (keying interface).

The antenna system can also be monitored for errors when some or even all of the base station's traffic channels are occupied.

The invention allows reliable and precise error monitoring of the antenna systems of base stations and can thus ensure reliable provision of the services of the digital radio network.

The invention will be explained in more detail below with reference to the exemplary embodiments schematically illustrated in the accompanying drawings. Show it:

Figure 1 - a schematic representation of a monitoring system according to the invention for error monitoring of an antenna system ei ner base station in a digital radio network;

FIG. 2 shows a schematic representation of an exemplary sequence of the method according to the invention;

FIG. 3 - a schematic representation of an exemplary time division multiplex structure.

FIG. 1 shows a schematic representation of an exemplary embodiment of a monitoring system 21 according to the invention for fault monitoring of an antenna system 6 of a base station 8 of a digital radio network 5. It can be seen that the monitoring system 21 has a base station 8 which is housed in a shelter 43. The base station 8 is for digital radio communication with partial Subscriber stations 9 of the radio network 5 set up a number of frequency channels assigned to the radio network 5. Each frequency channel has a time-division multiplex structure with successive time slots. At least one of the frequency channels has a linearization time slot which is provided in the time division multiplex structure so that the subscriber stations 9 can linearize their transmitters in this time slot.

Furthermore, it can be seen in FIG. 1 that the base station 8 has a total of four so-called channel units (CHUs) 41a, 41b, 41c, 41d, each of which includes a computer (not shown). Each of the four CHUs 41 a to 41 d is set up for communication with subscriber stations 9 of the radio network 5 via a pair of frequency channels (carrier, carrier). The digital radio network 5 uses a frequency division duplex (FDD). Each of the aforementioned pairs of frequency channels, i. H. each of the carrier comprises an uplink frequency channel (uplink channel) on which the subscriber stations 9 of the radio network 5 transmit and the base station 8 receives, and a downlink frequency channel (downlink channel) on which the base station 8 transmits and the subscriber stations 9 received.

In the exemplary embodiment shown here, the digital radio network 5 is a digital trunked radio network according to the TETRA standard, so that the time-division multiplex structure also corresponds to the TETRA standard. In the execution example, the linearization time slot is a time slot that is assigned to a common linearization channel (CLCH) of the TETRA standard. One of the four CHUs 41a to 41d, in this exemplary embodiment the CHU 41a, is responsible for sending and receiving data on the so-called Main Control Channel (MCCH) of the TETRA standard. This is a physical channel that is transmitted on a pair of frequency channels known as the main carrier. In the time division multiplex structure of the TETRA standard, the MCCH is transmitted on the main carrier in the first time slot of each frame comprising four time slots.

Furthermore, FIG. 1 shows that the base station 8 has an antenna system 6 which, in this exemplary embodiment, comprises a total of three antennas 6a, 6b, 6c. While the antennas 6a and 6b are transmit and receive is receiving antennas that are intended both for sending in the downlink and for receiving conditions in the uplink, the antenna 6c is a pure receiving antenna that is intended exclusively for receiving in the uplink. The antenna system 6 of the base station 8 furthermore comprises a line arrangement 17 via which the antennas 6a, 6b, 6c are connected to the base station 8. It can be seen that the base station 8 has two duplex filters 19a, 19b and a receive filter 19c for this purpose. The first duplex filter 19a is connected to the transmitting and receiving antenna 6a, the second duplex filter 19b is connected to the transmitting and receiving antenna 6b and the receiving filter 19c is connected to the receiving antenna 6c. Each of the four CHUs 41a to 41d is connected to each of the three antennas 6a, 6b, 6c and is set up to transmit signals on the pair of frequency channels (carriers) assigned to the respective CHU via one of the antennas 6a, 6b, 6c and to be able to receive signals via each of the antennas 6a, 6b, 6c.

Furthermore, it can be seen from FIG. 1 that the monitoring system 21 has a test device 7 which has a transmitter 13 and its own antenna 15 which is connected to the transmitter 13. The test device 7 also has a memory 31 and a computer 33. In this exemplary embodiment, the test device 7 is designed as a modified subscriber station of the digital radio network and is therefore set up for communication with the base station 8.

As FIG. 1 shows, the test device 7 is connected to an interface 25 of the base station 8. The test device 7 can be activated by an activation signal generated by the base station 8 and received by the test device 7 via the interface 25, and the test device 7 can be deactivated via a deactivation signal generated by the base station 8 and received by the test device 7 via the interface 25 .

Furthermore, in the exemplary embodiment shown in FIG. 1, the monitoring system 21 has a processing device 23 which is connected to the base station 8 of the digital radio network 5. The processing device 23 has a computer 29 and a memory 27. FIG. 1 also shows schematically that the test device 7 is set up to transmit a test signal 11 by means of the transmitter 13 and the antenna 15 of the test device 7. This test signal 11 is received by the base station 8 via the antenna system 6 of the base station 8.

The monitoring system 21, in particular the test device 7, the base station 8 and the processing device 23 of the monitoring system 21, are set up to carry out a method according to the invention for error monitoring of the antenna system 6 of the base station 8. In this exemplary embodiment, the test device 7 is set up to carry out steps a) and b) of the method, the base station 8 is set up to carry out steps c) and d) of the method and the processing device 23 is set up to carry out step e) .

The method according to the invention is explained in more detail below with reference to FIG. FIG. 2 shows a schematic representation of an exemplary sequence of method steps a), b), c), d) and e) of a method according to the invention for error monitoring of the antenna system 6 of the base station 8 of the digital radio network 5 by means of the test device 7.

In step a) of the exemplary embodiment explained here, the test device 7 initially determines a target channel for transmitting the test signal 11. For this purpose, the test device 7 listens to a plurality of downlink frequency channels, the listened to downlink frequency channels being taken from a predetermined list which contains downlink frequency channels whose received power exceeds a predetermined minimum value. For each of the tapped downlink frequency channels, the test device 7 checks whether an MCCH is transmitted on this downlink frequency channel. On this basis, the test device 7 can recognize whether the downlink frequency channel that is being listened to belongs to a main carrier of the TETRA trunked radio network 5. In this case, the test device selects the uplink frequency channel of the main carrier whose downlink frequency channel the test device with the greatest received power receives as the target channel. In addition, the test device listens to the MCCH on each downlink frequency channel belonging to a main carrier and decodes signaling information from the base station 8 are transmitted to the MCCH and indicate a network operator of the radio network 5. On this basis, the test device 7 can check whether the base station transmitting the signaling information on the MCCH is the base station 8 to be monitored, and on this basis it can ensure that the selected target channel is an uplink frequency channel which is used by base station 8 for reception.

After the test device 7 has determined the target channel for the transmission of the test signal 11, the test device 7 selects in step a) a time slot on the target channel as the test signal time slot.

In the exemplary embodiment explained here, a linearization time slot is used for this purpose. The test device 7 therefore first determines the linearization time slot on the target channel, i. H. it determines the temporal position of the linearization time slot within the time division multiplex structure of the target channel. For this purpose, the test device 7 decodes signaling information that is transmitted from the base station 8 on an Access Assignment Channel (AACH) and displays a linearization time slot, namely a time slot assigned to the Common Linearization Channel (CLCH) of the TETRA standard is. The CLCH is a logical channel in the uplink of the TETRA standard. The temporal position of the CLCH, i.e. the temporal position of the time slot assigned to the CLCH, is indicated by the signaling information transmitted on the AACH. In step a) of the exemplary embodiment explained here, the test device 7 selects the linearization time slot determined in this way as the test signal time slot.

The linearization time slot is a time slot which is repeated at time intervals predetermined by the time-multiplex structure, as shown schematically in FIG. FIG. 3 shows a time division multiplex structure 39a of an uplink frequency channel and a time division multiplex structure 39b of a downlink frequency channel of a digital trunked radio network according to the TETRA standard. The uplink frequency channel shown in FIG. 3 and the downlink frequency channel shown in FIG. 3 together form a carrier, ie a pair of frequency channels according to the TETRA standard, in this exemplary embodiment a main carrier. It can be seen that the time-division multiplex structures 39a, 39b on the respective Frequency channel available time is divided into frames F1 to F18. Each 18 frames F1 to F18 are combined to form a multiframe 35. Each individual frame F1 to F18 comprises four time slots 37, to which the time slot numbers 1 to 4 (timeslot number, TN for short) are assigned. The combination of a pair of frequency channels (uplink and downlink) and one of the four time slots 37 of each frame F1 to F18 forms a physical channel according to the TETRA standard, ie each carrier comprises four physical channels.

The 18th frame F18 of each multiframe 35, also shown in FIG. 3, is referred to as a control frame in the TETRA standard. One of the four time slots 37 (time slot number 1, 2, 3 or 4) of each control frame F18 in the time division multiplex structure 39a of the uplink frequency channel is assigned to the common linearization channel (CLCH), ie this time slot is a linearization -Time slot within the meaning of the present invention. In the exemplary embodiment shown in FIG. 3, the linearization time slot (i.e. the time slot of the CLCH) is time slot 37 with time slot number 2 in control frame F18 of the uplink frequency channel. According to the TETRA standard, the time slot 37 of the control frame F18, which is assigned to the CLCH and thus forms the linearization time slot, varies from multiframe to multiframe and results as

TN = 4 - (MN + 1) mod 4, where TN denotes the timeslot number in the control frame F18 and MN the multiframe number (multiframe number). The time slot of the CLCFI, i.e. the linearization time slot, is actually provided in the TETRA standard so that the subscriber stations 9 can carry out a linearization of their transmitters in this time slot.

In addition, in step a) shown in FIG. 2, the test device 7 determines a received power, ie a reception quality, of a downlink signal transmitted by the base station 8 and received by the test device 7. For this purpose, the test device determines a Received Signal Strength Indicator (RSSI) of the received downlink signal. FIG. 2 also shows that the test device then transmits the test signal 11 in step b) by means of its transmitter 13 and its antenna 15. The test signal 11 is transmitted in the test signal time slot, which in this exemplary embodiment is a linearization time slot, ie the test signal 11 is transmitted during the duration of the time slot 2 shown in FIG. 3 in the control frame F18 of the main carrier's uplink frequency channel.

With the test signal, the test device 7 transmits a test message that can be decoded by the base station 8. The test message contains information about the reception quality determined in step a) of a downlink signal transmitted by the base station 8 and received by the test device 7 in the form of the associated RSSI value. The test message also contains an identifier of the test device 7 and an identifier of the base station 8 and information about a transmission power of the test signal 11 transmitted by the test device 7.

In step c) of the method according to the invention, also shown in FIG. 2, the test signal 11 is received by the base station 8 via the antenna system 6.

Then, in step d), the base station 8 determines a reception quality of the test signal 11 received by means of the antenna system 6 of the base station 8. For each of the antennas 6a, 6b, 6c of the antenna system 6 set up to receive radio signals, an antenna-related reception quality of the with by means of the respective antenna received test signal 11 is determined. For this purpose, the base station 8 determines a Received Signal Strength Indicator (RSSI) of the received test signal 11 for each antenna 6a, 6b, 6c. The RSSI values determined are forwarded from the base station 8 to the processing device 23.

Steps b), c) and d) of the sequence of the inventive method shown as an example in FIG. 2 are carried out with each repetition of the linearization time slot, ie with each repetition of the multiframe 35 shown in FIG Control Frame F18 contains run again. With each repetition of steps b) to d), the base station 8 thus determines a reception quality of the test signal received in each case in the form of an RSSI value and forwards each determined RSSI value to the processing device 23.

On the basis of the RSSI values determined in this way, the processing device 23 generates an evaluation of the time course of the reception quality in step e) of the method shown in FIG. 2, namely in the form of a calculation of a moving average of the RSSI values as a variable derived from the reception quality.

In step e), the processing device 23 recognizes an error in the antenna system 6 as a function of the evaluation of the time profile and generates an output as a function of the evaluation of the time profile, which is used for error monitoring of the antenna system 6. A warning is generated as output for the antenna concerned when the associated moving RSSI average falls below a predetermined first threshold value. On the other hand, an alarm is generated as an output if the moving average falls below a predetermined second threshold value, which is smaller than the first threshold value.

The first and second threshold values are threshold values for the reception quality and are calculated on the basis of a reference value for the reception quality, namely on the basis of an RSSI reference value. For this purpose, a threshold value of the deviation is subtracted from the reference value of the reception quality. In the exemplary embodiment explained here, the threshold value for the deviation for generating a warning is 3 dB, while the threshold value for the deviation for generating an alarm is 10 dB. A warning is therefore generated if the moving RSSI mean value falls below the RSSI reference value by more than 3 dB. An alarm is generated if the moving RSSI mean value falls below the RSSI reference value by more than 10 dB.

On the basis of the method described, reliable and precise error monitoring of the antenna system 6 of the base station 8 is possible. It is advantageously possible to use each of the antennas 6a, 6b, 6c of the antenna system 6 and each of the respective antenna 6a, 6b, 6c associated connecting line to be monitored individually. In this way, the method according to the invention can be used to determine which antenna 6a, 6b, 6c of antenna system 6 and / or which associated connecting line is affected by a possible error.

List of reference symbols

Time slot number (TN)

5 digital radio network

6 antenna system

6a, 6b, 6c antennas of the base station

7 test facility

8 base station 9 subscriber station 11 test signal 13 transmitter of the test device 15 antenna of the test device 17 line arrangement

19a, 19b duplex filter 19c reception filter 21 monitoring system 23 processing device 25 interface of the base station 27 memory of the processing device 29 computer of the processing device 31 memory of the test device 33 computer of the test device 35 multiframe 37 time slot

39a, 39b time division multiplex structure

41a, 41 b, 41c, 41 d Channel Unit (CHU) 43 Shelter

F1 to F18 frame

Claims

1. A method for fault monitoring of an antenna system (6) of a base station (8) of a digital radio network (5) by means of a test device (7) which has a transmitter set up for transmission of radio signals, where the base station (8) for a Communication with subscriber stations (9) of the radio network (5) via a number of the radio network (5) associated frequency channels is set up and each frequency channel has a time division multiplex structure (39a, 39b) with successive time slots (37), with the following steps : a) selection of at least one time slot as a test signal time slot by the test device (7), b) transmission of a test signal (11) in the test signal time slot by the test device (7), the test signal (11) by means of the transmitter (13) the test device (7) is transmitted via an antenna (6a, 6b, 6c, 15) connected to the transmitter (13) of the test device (7), c) the base receives the test signal (11) station (8), the test signal (11) being received via the antenna system (6) of the base station (8), d) determining a reception quality of the test signal (11) received by means of the antenna system (6) of the base station (8), e) Detection of a fault in the antenna system (6) as a function of the reception quality of the received test signal (11).

2. The method according to claim 1, characterized in that the time slot (37) which is selected as the test signal time slot in step a) and is used in step b) for transmitting the test signal (11) is a time slot (37) who is in the time division multiplex structure (39a, 39b) is not intended for communication between different stations (8, 9) of the digital radio network (5).

3. The method according to claim 1 or 2, characterized in that at least one of the frequency channels has a linearization time slot which is provided in the time division multiplex structure (39a, 39b) so that the subscriber stations (9) in this time slot (37 ) can perform a linearization of their transmitters, the time slot (37), which is selected in step a) as the test signal time slot and is used in step b) for transmitting the test signal (11), is such a linearization time slot.

4. The method according to any one of the preceding claims, characterized in that the time slot (37) which is selected as a test signal time slot in step a) and is used in step b) for transmitting the test signal (11) is a time slot (37) which is assigned to a traffic channel in the time division multiplex structure (39a, 39b).

5. The method according to any one of the preceding claims, characterized in that the test device (7) in step a) of the method, like a subscriber station (9), is booked into a radio cell of the digital radio network (5) assigned to the base station (8), wherein the time slot (37), which is selected in step a) as the test signal time slot and is used in step b) for the transmission of the test signal (11), is an assigned time slot which the base station (8) of the registered test device ( 7) for a transmission of radio signals.

6. The method according to claim 5, characterized in that the test device (7) is booked into the radio cell assigned to the base station (8) with a priority that is lower than the priority of the other subscriber stations (9) booked into the radio cell .

7. The method according to any one of the preceding claims, characterized in that in step a) of the method, the test device (7) at least one that listens to frequency channels and at least one free time slot that is assigned to a traffic channel in the time division multiplex structure (39a, 39b) and is currently not being used for the transmission of radio signals, the time slot (37) that was specified in step a ) is selected as the test signal time slot and is used in step b) for the transmission of the test signal (11), which is the free time slot determined in this way.

8. The method according to any one of the preceding claims, characterized in that the test device (7) has its own antenna (15) which is connected to the transmitter (13) of the test device (7), and in step b) the test signal ( 11) is transmitted via the antenna (15) of the test device (7).

9. The method according to any one of the preceding claims, characterized in that the antenna system (6) has a plurality of antennas (6a, 6b, 6c) and the transmitter (13) of the test device (7) is connected to at least one first antenna the antenna system (6) of the base station (8), which is designed as a transmitting antenna or as a receiving antenna or as a combined transmitting and receiving antenna, wherein in step b) the test signal (11) is transmitted via the first antenna and in step c) the test signal (11) is received via at least one second antenna of the antenna system (6) of the base station (8), which is different from the first antenna and is designed as a receiving antenna or as a combined transmitting and receiving antenna.

10. The method according to claim 9, characterized in that the antenna system (6) has a plurality of antennas set up for the reception of radio signals (6a, 6b, 6c), which are each designed as a receiving antenna or as a combined transmitting and receiving antenna, wherein in step c) the test signal (11) is received via the plurality of antennas (6a, 6b, 6c) set up to receive radio signals and in step d) for each of the antennas (6a, 6b, 6c) set up to receive radio signals ) an antenna-related reception quality of the test signal (11) received by means of the respective antenna is determined and in step e) an antenna (6a, 6b, 6c) of the antenna system (6) affected by an error is recognized by comparing the antenna-related reception qualities.

11. The method according to claim 9 or 10, characterized in that in step d) for at least one antenna (6a, 6b, 6c) of the antenna system (6) set up for the reception of radio signals, an antenna-related reception quality of the respective antenna (6a , 6b, 6c) received test signal (11) is determined and in step e) an antenna (6a, 6b, 6c) of the antenna system (6) affected by an error is recognized as a function of the antenna-related reception quality and a result of a reflection measurement of at least one antenna (6a, 6b, 6c) of the antenna system (6).

12. The method according to any one of the preceding claims, characterized in that in step a) the test device (7) a reception quality, in particular a reception power, of a downlink signal transmitted by the base station (8) and received by the test device (7) certainly.

13. The method according to claim 12, characterized in that in step b) the test device (7) with the test signal (11) transmits a test message which can be decoded by the base station (8), the test message information about a reception quality, in particular via a receiving line, a downlink signal transmitted by the base station (8) and received by the test device (7).

14. The method according to any one of the preceding claims, characterized in that the time slot (37) which the test device selects in step a) as the test signal time slot is a time slot (37) which is divided into by the time multiplex Structure (39a, 39b) repeated at predetermined time intervals, with at least steps b), c) and d) being carried out for each repetition or at least for some of the repetitions of the time slot (37).

15. The method according to any one of the preceding claims, characterized in that in step a) the test device (7) determines one of the frequency channels as the target channel for transmitting the test signal (11) and selects the test signal time slot on the target channel and in step b) the test device (7) transmits the test signal (11) in the test signal time slot on the target channel.

16. The method according to any one of the preceding claims, characterized in that the frequency channels comprise a number of uplink frequency channels and a number of downlink frequency channels, the test signal time slot selected in step a) being a time slot (37) of an associated uplink Frequency channel and the test signal (11) is transmitted in step b) in the test signal time slot on the associated uplink frequency channel, and / or the target channel is an uplink frequency channel.

17. The method according to any one of the preceding claims, characterized in that in step a) the test device (7) for selecting the test signal time slot and / or for determining the time slot (37) in the time division multiplex structure (39a , 39b) is not intended for communication between different stations of the digital radio network, and / or to determine the linearization time slot listens to at least one signaling channel of the radio network (5) and decodes signaling information sent by the base station (8) on the signaling channel be transmitted.

18. The method according to any one of the preceding claims, characterized in that the digital radio network (5) is a digital trunked radio network, in particular a digital trunked radio network according to the TETRA standard.

19. The method according to any one of the preceding claims, characterized in that the digital radio network (5) and the time division multiplex structure (39a, 39b) correspond to the TETRA standard and the test signal time slot is a linearization time slot that is a common Linearization Channel (CLCH) of the TETRA standard is assigned.

20. The method according to any one of the preceding claims, characterized in that the digital radio network (5) and the time division multiplex structure (39a, 39b) correspond to the TETRA standard and in step a) the test device (7) for determining the target channel and / or selecting the test signal time slot and / or listening to a main control channel (MCCH) on at least one frequency channel to determine the linearization time slot and decoding signaling information that is transmitted by the base station (8) on the main control channel (MCCH), and or

Signaling information is decoded, which is transmitted from the base station (8) on an Access Assignment Channel (AACH).

21. The method according to any one of the preceding claims, characterized in that in step e) an output is generated which is used for error monitoring of the antenna system (6), a warning being generated as an output if the reception quality and / or one of the Reception quality derived quantity fulfills a first condition, in particular falls below a predetermined first threshold value of the reception quality, and / or an alarm is generated from the output if the reception quality and / or the quantity derived from the reception quality meets a second condition, in particular a predetermined second threshold value of the Receipt quality falls below, and wherein the second threshold value of the reception quality is smaller than the first threshold value of the reception quality.

22. The method according to claim 21, characterized in that the threshold value of the reception quality and / or a reference value of the reception quality are determined from the reception quality of one or more received test signals (11).

23. The method according to any one of the preceding claims, characterized in that at least steps b), c) and d) are repeated at time intervals and in step e) an evaluation of a time profile of the reception quality of the test signals (11) received by the base station (8) is generated and the output is generated as a function of the evaluation of the time profile.

24. The method according to claim 23, characterized in that an error classification is carried out in step e) by comparing the evaluation of the time profile of the reception quality with stored comparison data and, depending on this comparison, determining an error type and generating an output, which includes information about the type of error detected.

25. The method according to any one of the preceding claims, characterized in that the test device (7) repeats the transmission of the test signal (11) at time intervals and the test device (7) at least one signaling channel of the radio network, in particular a main control channel ( MCCFI) of the TETRA standard, listens and receives downlink signals that are transmitted from the base station (8) on the signaling channel, the test device (7) terminating the repeated transmission of the test signal (11) when the test device (7) can no longer receive the downlink signals on the wired signaling channel and / or if the received power of the downlink signals received on the signaling channel falls below a predetermined threshold value of the received power.

26. Monitoring system (21) for fault monitoring of an antenna system (6) of a base station (8) of a digital radio network (5), the monitoring system (21) having the base station (8) which is responsible for communication with subscriber stations (9) of the Radio network (5) is set up via a number of frequency channels assigned to the radio network (5), each frequency channel having a time-division multiplex structure (39a, 39b) with successive time slots, and wherein the monitoring system (21) has a test device (7), one set up for the transmission of radio signals and with an antenna (6a, 6b, 6c, 15) connected transmitter (13), characterized in that the monitoring system (21) is set up to carry out a method according to one of the preceding claims.

27. Monitoring system (21) according to the preceding claim, characterized in that the monitoring system (21) has a processing device (23) which is connected to a number of base stations (8) of the digital radio network and for performing step e) or is set up to carry out step d) and step e) of a method according to one of the preceding claims.

28. Monitoring system (21) according to claim 26 or 27, characterized in that the test device (7) and / or the processing device (23) and / or the monitoring system (21) for error monitoring of a plurality of antenna systems (6) of a plurality of base stations (8) of the digita len radio network (5) are set up.

29. Test device (7) of a monitoring system (21) according to one of claims 26 to 28.

30. Test device (7) according to the preceding claim, characterized in that the test device (7) is set up to be connected to an interface (25) of the base station (8), in particular to an alarm output of the base station (8) and to be activated by an activation signal generated by the base station (8) and received by the test device (7) via the interface (25) and / or by an activation signal generated by the base station (8) and received by the test device ( 7) to be deactivated via the interface (25) received deactivation signal.

31. Test device (7) according to claim 29 or 30, characterized in that the test device (7) is designed as a modified subscriber station (9) of the digital radio network (5).

32. Base station (8) of a monitoring system (21) according to one of Claims 26 to 28.

33. Computer program with program code means, set up to carry out a method according to one of claims 1 to 25, when the computer program is executed on at least one computer (29, 33), the computer (29, 33) being a computer of a monitoring system (21) according to one of claims 26 to 28 and / or a computer (33) of a test device (7) according to one of claims 29 to 31 and / or a computer (29) of a base station (8) according to claim 32 and / or a computer a processing device

(23) of a monitoring system (21) according to one of claims 26 to 28.