DE102019134540B4 - Method for fault monitoring of an antenna system of a base station, monitoring system, test device, base station and computer program for this - Google Patents

Abstract

A method is described 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 the transmission of radio signals, the base station (8) 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) and each frequency channel has a time-division multiplex structure (39a, 39b) with successive time slots (37), with the steps: a) Selecting at least one time slot as a test signal time slot through 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) of 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 test signal (11) is received by the base isstation (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). An associated monitoring system (21), a test device (7), a base station (8) and a computer program are also described.

Description

The invention relates to a method for fault monitoring of an antenna system of a 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 comprise all 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 provides for communication between base stations and subscriber stations in 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, in particular 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.

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), the antenna system of a base station is usually attached in an exposed position, e.g. 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 possible . The spectrum of errors that occur here ranges from a gradual deterioration in the transmission and reception quality due to moisture damage to completely demolished antennas and the associated sudden failure of the base station, e.g. 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, i.e. it is necessary to monitor the antenna systems of the base stations with regard to a possible occurrence of antenna system errors.

From the prior art it is known to measure a voltage standing wave ratio (VSWR), a return loss or other variables that indicate the quality of the line adaptation on the antenna line (reflection measurement) for fault monitoring of antennas. 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 on an antenna of a base station are, for example, from FIG US 6,313,644 B1 famous.

Such methods for error monitoring of the antenna systems of base stations based on reflection measurements, e.g. 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 monitoring accuracy, since the accuracy is limited, for example, by the attenuation of the connecting lines. Gradual changes in the performance of the Antenna systems, which can be caused, for example, by water penetrating 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, ie antennas of the base stations exclusively intended for signal reception, cannot be monitored in this way.

DE 694 26 621 T2 discloses a method and apparatus for testing a base station in a time division multiple access radio communication system. A lower cost radio frequency test loop is used to avoid expensive signal processing equipment. Here, the base station transmitter transmits an RF carrier signal from the base station during a relinquished uplink time slot, the RF signal from the transmitter being coupled to a radio frequency test loop circuit. This causes a conversion of the RF carrier frequency of the transmitter to an RF carrier frequency with the capability of reception by the receiver of the base station during a predetermined uplink time slot. The received RF carrier signal can then be tested to determine the bit error rate, the transmission signal level, the reception sensitivity or the like. A loop is formed between a given downlink time slot and a given uplink time slot.

B. Walke: Cellular networks and their protocols, Vol. 2, trunked radio, cordless telephone system, W-ATM, HIPERLAN, satellite radio, UPT.2., Revised and expanded edition, Stuttgart: BG Teubner GmbH, 2000, pp. 15-83 is the TETRA standard. In the TETRA standard, the channel 18 is provided a linearization channel CLCH for the uplink of the mobile station and a linearization channel BLCH for the downlink. When a CLCH occurs, mobile stations can linearize their transmitters on any physical control channel CP.

DE 699 35 441 T2 discloses a method and arrangement for testing a receiving antenna of a radio system. A radio frequency test signal with a frequency within the frequency band of the receiver is coupled into the antenna of the transmitter and thereby also into the antenna of the receiving unit. An evaluation unit, which is connected to the receiver unit, evaluates the received signal in order to determine the integrity of the receiver antenna. The test signal source can transmit a signal within a reserve channel that is not continuously used by the receiver. As a result, the checking procedure can be carried out continuously without disturbing the ongoing traffic.

GB 2 321 574 A describes a communication system with a plurality of remote communication units. The communication system sees time-divided periods. Communication takes place in a multiframe structure with 18 frames, which in turn are divided into four time slots. The linearization channel CLCH of the TETRA standard in the 18th frame is to be used to linearize the receivers.

DE 694 26 255 T2 discloses a method and a device for measuring a state of a base station, test measurements being carried out in predetermined TDMA time slots. For this purpose, a radio frequency test signal is sent in a time slot of an IDLE frame of a channel structure or in time slots of an IDLE frame of a channel structure on a radio channel of the base station and received by the receiver in order to determine the status of the base station on the basis of the received frequency test signal. The test signal can be sent by a part in the terminal or a special test device and received by the receiving unit of a base station and processed there in a frame unit.

Starting from this, the object of the present invention is 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 having the features of claim 1 for fault monitoring of an antenna system of a base station of a digital radio network by means of a test device.

The test device has a transmitter set up for the transmission of radio signals. The base station is set up for communication with subscriber stations in 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.

1. a) Auswählen mindestens eines Zeitschlitzes als Testsignal-Zeitschlitz durch die Testeinrichtung,
2. b) Übertragen eines Testsignals in dem Testsignal-Zeitschlitz durch die Testeinrichtung, wobei das Testsignal mittels des Senders der Testeinrichtung über eine mit dem Sender der Testeinrichtung verbundene Antenne übertragen wird,
3. c) Empfangen des Testsignals durch die Basisstation, wobei das Testsignal über die Antennenanlage der Basisstation empfangen wird,
4. d) Ermitteln einer Empfangsqualität des mittels der Antennenanlage der Basisstation empfangenen Testsignals,
5. e) Erkennen eines Fehlers der Antennenanlage in Abhängigkeit der Empfangsqualität des empfangenen Testsignals.

The procedure consists of the following steps:

1. a) the test device selects at least one time slot as the test signal time slot,
2. b) Transmission of a test signal in the test signal time slot by the test device, the test signal by means of the transmitter Test device is transmitted via an antenna connected to the transmitter of the test device,
3. c) Receiving the test signal by the base station, the test signal being received via the antenna system of the base station,
4. d) determining a reception quality of the test signal received by means of the antenna system of the base station,
5. e) Detection of a fault in the antenna system as a function of the reception quality of the received test signal.

According to the invention, it is provided that at least steps b), c) and d) are repeated at time intervals and an evaluation of a time profile of the reception quality of the test signals received by the base station is generated in step e). 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.

This offers the advantages that permanent monitoring of the antenna system is made possible and, moreover, gradual changes in the reception quality can be determined by evaluating the temporal profile and, on this basis, creeping error profiles of the antenna system can also be recognized.

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 deteriorations in reception quality can be detected and conclusions can be drawn on this basis about a fault in the antenna system, e.g. caused by the ingress of 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 that 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 not used in the time division multiplex structure for a Communication between different stations of the digital radio network is provided.

It is therefore proposed that the test signal be transmitted in a time slot (i.e. during the duration of a time slot) of the time division multiplex structure which is not intended for communication between different stations, i.e. H. is not intended for communication between different subscriber stations and not for communication between subscriber stations and base stations and not 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 which is provided in the time division multiplex structure for a self-test of the subscriber stations and / or the base stations. 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 time slots that are not intended for communication between different stations of the digital radio network can be specified in the time division multiplex structure of the radio network in particular by a logical channel intended for this purpose, e.g. 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. Reliable and interference-free fault monitoring of the antenna system is thus even possible when the digital radio network is fully utilized, that is to say even when all of them Traffic channels of 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 for transmitting the test signal in step b) 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 (i.e. during the duration of such a time slot). Such a linearization time slot is provided in the time division multiplex structure of some digital radio networks, in particular digital mobile radio networks and digital trunked radio networks, so that the subscriber stations can linearize their transmitters in this time slot. 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, i.e. on the frequency channels intended for the uplink.

A linearization time slot is therefore an example of a time slot of the type explained above which is not provided in the time division multiplex structure for communication between different stations (base station or subscriber station) of the digital radio network. A 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, the time slots of which 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), which includes a division of the 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 that 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 that is a traffic channel in the time division 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. The 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 as a Subscriber station is registered in a radio cell of the digital radio network assigned to the base station. The time slot that is selected as the test signal time slot in step a) and used for transmitting the test signal in step b) 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 mean the process that is customary in digital radio networks, in which the subscriber station registers itself in a specific radio cell, ie. H. registers (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 logged into the radio cell assigned to the base station with a priority that is lower than the priority of the other subscriber stations logged into the radio cell.

Such a development of the invention offers the advantage that in this way 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 be largely avoided. 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. Avoiding 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 is assigned to a traffic channel in the time-division multiplex structure and not specifically for the transmission of radio signals is being used. 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. As an alternative or in addition, it is also conceivable for the test device to listen to a signaling channel (control channel) on which information about the occupancy of the time slots is transmitted in order to determine the free time slot.

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 is required between the test device and the base station.

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 (fading) 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 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 usually optimally positioned on the transmission mast anyway, there is no need for the complex positioning of an additional antenna.

• - in Schritt c) das Testsignal über die Mehrzahl für den Empfang von Funksignalen eingerichteter Antennen empfangen wird und
• - in Schritt d) für jede der für den Empfang von Funksignalen eingerichteten Antennen jeweils eine antennenbezogene Empfangsqualität des mittels der jeweiligen Antenne empfangenen Testsignals ermittelt wird und
• - in Schritt e) eine von einem Fehler betroffene Antenne der Antennenanlage durch einen Vergleich der antennenbezogenen Empfangsqualitäten erkannt wird.

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 is received via the plurality of antennas set up for the reception of radio signals, and
• - In step d) an antenna-related reception quality of the test signal received by means of the respective antenna is determined for each of the antennas set up for the reception of radio signals, 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 an unusually poor reception quality. If this applies to all antennas of the antenna system via which the test signal was received, a fault in the antenna via which the test signal was transmitted can be assumed. 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 namely 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 Schritt d) für mindestens eine für den Empfang von Funksignalen eingerichtete Antenne der Antennenanlage jeweils eine antennenbezogene Empfangsqualität des mittels der jeweiligen Antenne empfangenen Testsignals ermittelt wird und
• - in Schritt e) eine von einem Fehler betroffene Antenne der Antennenanlage erkannt wird in Abhängigkeit der antennenbezogenen Empfangsqualität und eines Ergebnisses einer Reflexionsmessung mindestens einer Antenne der Antennenanlage.

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 which is set up to receive radio signals, and
• - In step e) an antenna of the antenna system affected by an error is detected 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 voltage standing wave ratio (VSWR for short) and / or a return loss (return loss) and / or other variables that indicate the quality of the line adaptation, be.

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 facility perform 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 transmission antennas of the antenna system and the associated connecting lines can also be monitored, i.e. 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, of a downlink signal transmitted by the base station and received by the test device.

It is accordingly 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 possibilities for using 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 be able

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 multiframe 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 each multiframe, namely in the so-called control frame (the 18th frame) of the multiframe, wherein the exact position of the linearization time slot of the CLCH according to the TETRA standard varies 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 as Test signal time slot selected time slot, e.g. B. the linearization time slot can be performed. It is conceivable, for example, that the steps mentioned in 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 antenna system make possible. Furthermore, it is possible in this way to determine a time curve 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 also be detected in the event of a gradual 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 determines the test signal in the test signal Transmits time slot on the target channel.

The target channel is the frequency channel that is used for the transmission of the test signal by the test device. This can particularly advantageously 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 to 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, i.e. 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 when a plurality of frequency channels are assigned to the digital radio network .

• - der in Schritt a) ausgewählte Testsignal-Zeitschlitz ein Zeitschlitz eines zugehörigen Uplink-Frequenzkanals ist und das Testsignal in Schritt b) in dem Testsignal-Zeitschlitz auf dem zugehörigen Uplink-Frequenzkanal übertragen wird, und/oder
• - der Zielkanal ein Uplink-Frequenzkanal ist.

In a further advantageous development of the invention it is provided that the frequency channels include a number of uplink frequency channels and a number of downlink frequency channels, wherein

• the test signal time slot selected in step a) is a time slot of an associated uplink frequency channel and the test signal 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.

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. It is provided that the test signal is 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 the need for modifications to the base station. The reason for this is that the reception filters or reception branches of the duplex filters of the base station are set up anyway for signal reception on the uplink channel. For reliable and precise error monitoring, it is therefore only necessary for the base station to listen 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 listens to a plurality of downlink frequency channels, in particular the downlink frequency channels of a predetermined list of frequency channels, and 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 that 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 the 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 is transmitting. This provides a simple way to determine the carrier used by the base station to be monitored, ie the pair of frequency channels (uplink and downlink frequency channel) used by the base station to be monitored, and to select the target channel on this basis.

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 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 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).

• - einen Main Control Channel (MCCH) auf mindestens einem Frequenzkanal abhört und Signalisierungsinformationen dekodiert, die von der Basisstation auf dem Main Control Channel (MCCH) übermittelt werden, und/oder
• - Signalisierungsinformationen dekodiert, die von der Basisstation auf einem Access Assignment Channel (AACH) übermittelt werden.

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 that is transmitted by the base station on the main control channel (MCCH), and / or
• - Decoded signaling information that is transmitted by the base station on an Access Assignment Channel (AACH).

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 by 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 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, 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 for the reception quality.

In a further advantageous development of the invention it is provided that in step e) an output is generated which is used to monitor the antenna system for errors.

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 a predefined threshold value for the reception quality falls below.

• - eine Warnung erzeugt wird, wenn die Empfangsqualität und/oder die aus der Empfangsqualität abgeleitete Größe eine erste Bedingung erfüllt, insbesondere einen vorgegebenen ersten Schwellenwert der Empfangsqualität unterschreitet, und/oder
• - ein Alarm erzeugt wird, wenn die Empfangsqualität und/oder die aus der Empfangsqualität abgeleitete Größe eine zweite Bedingung erfüllt, insbesondere einen vorgegebenen zweiten Schwellenwert der Empfangsqualität unterschreitet,

wobei der zweite Schwellenwert der Empfangsqualität kleiner ist als der erste Schwellenwert der Empfangsqualität.In a further advantageous development of the invention it is provided that the output in step e)

• a warning is generated when the reception quality and / or the variable derived from the reception quality fulfills 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,

wherein the second threshold value of the reception quality is smaller than the first threshold value of 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, e.g. 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 recognized and / or a warning and / or an alarm is generated in the manner explained above if the deviation in the reception quality exceeds the threshold value of the deviation in terms of 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 when 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 a fault in the antenna system, so that 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 in that a reference value for the reception quality is determined 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 can be determined simply, automatically and reliably.

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 sliding 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 comparing the evaluation of the time profile of the reception quality with stored comparison data and determining an error type as a function of this comparison, and generating an output that includes information about the type of error detected.

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 which are characteristic of certain types of errors. For example, an abrupt deterioration in the reception quality can be characteristic of a torn antenna and a gradual deterioration in the 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 “penetration of moisture”.

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

In a further advantageous development of the invention it is provided that the test device repeats the transmission of the test signal at time intervals and the test device repeats at least one signaling channel of the Radio network, in particular a Main Control Channel (MCCH) of the TETRA standard, and receives downlink signals 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 receives the downlink signals can no longer receive on the tapped 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.

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 digital radio network with the features of claim Art set up.

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 fault 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, which is part of the base station, or as an external computer which 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 which 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 to be activated by an activation signal generated by the base station and received by the test device via the interface 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 it is, on the one hand, a simple and therefore enables inexpensive provision of the test device and, on the other hand, 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.

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

• - Eine individuelle Frequenzkonfiguration der Testeinrichtung ist nicht erforderlich, da die Testeinrichtung durch ein Scanning der Frequenzkanäle automatisch erkennen kann, welche Frequenzkanäle die zu überwachende Basisstation nutzt. Auf diese Weise ist es auch vorteilhaft möglich, dass die Testeinrichtung automatisch auf Änderungen der von der zu überwachenden Basisstation genutzten Frequenzkanäle reagiert.
• - Da es sich bei der Testeinrichtung um eine Einrichtung auf Grundlage einer Teilnehmerstation des digitalen Funknetzes handeln kann, ist es auf einfache Art und Weise möglich, eine multibandfähige Testeinrichtung bereitzustellen. Dadurch entfällt in vorteilhafter Weise die Notwendigkeit, verschiedene Hardware-Varianten der Testeinrichtung für verschiedene Frequenzbänder zur Verfügung vorsehen zu müssen.
• - Ein weiterer Vorteil der Erfindung liegt darin, dass zur Fehlerüberwachung eine Belegung eines Verkehrskanals des digitalen Funknetzes nicht erforderlich ist. Dementsprechend ist auch keine Schnittstelle zum Belegen eines Verkehrskanals zwischen der Testeinrichtung und der Basisstation (Keying Interface) erforderlich.
• - Die Fehlerüberwachung der Antennenanlage kann auch dann erfolgen, wenn einige oder sogar sämtliche Verkehrskanäle der Basisstation belegt sind.
• - Die Erfindung erlaubt eine zuverlässige und genaue Fehlerüberwachung der Antennenanlagen von Basisstationen und kann damit eine zuverlässige Bereitstellung der Dienste des digitalen Funknetzes sicherstellen.

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 necessary, 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.
• 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 busy.
• 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.

• 1 - eine schematische Darstellung eines erfindungsgemäßen Überwachungssystems zur Fehlerüberwachung einer Antennenanlage einer Basisstation in einem digitalen Funknetz;
• 2 - eine schematische Darstellung eines beispielhaften Ablaufs des erfindungsgemäßen Verfahrens;
• 3 - eine schematische Darstellung einer beispielhaften Zeitmultiplex-Struktur.

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

• 1 a schematic representation of a monitoring system according to the invention for fault monitoring of an antenna system of a base station in a digital radio network;
• 2 - a schematic representation of an exemplary sequence of the method according to the invention;
• 3 a schematic representation of an exemplary time division multiplex structure.

the 1 shows a schematic representation of an embodiment of a monitoring system according to the invention 21 for error monitoring of an antenna system 6th a base station 8th of a digital radio network 5 . It can be seen that the surveillance system 21 a base station 8th having that in a shelter 43 is housed. The base station 8th is for digital radio communication with subscriber stations 9 of the radio network 5 over a number of the radio network 5 assigned frequency channels. 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 for the subscriber stations 9 can perform a linearization of their transmitters in this time slot.

Furthermore, in the 1 recognizable that the base station 8th a total of four so-called channel units (CHUs) 41a , 41b , 41c , 41 d each having a computer (not shown). Each of the four CHUs 41 a until 41 d is for communication with subscriber stations 9 of the radio network 5 established over a pair of frequency channels (carrier, carrier). The digital radio network 5 uses Frequency Division Duplex (FDD). Each of the aforementioned pairs of frequency channels, ie each carrier, comprises an uplink frequency channel (uplink channel) on which the subscriber stations 9 of the radio network 5 send and the base station 8th receives, and a downlink frequency channel (downlink channel) on which the base station 8th sends and the subscriber stations 9 receive.

The digital radio network 5 is in the embodiment shown here 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 exemplary embodiment, 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 until 41d , in this 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, in the 1 shown that the base station 8th an antenna system 6th has, in this embodiment a total of three antennas 6a , 6b , 6c includes. While it is with the antennas 6a and 6b It is a matter of transmitting and receiving antennas that are intended both for sending in the downlink and for receiving in the uplink, the antenna is 6c a pure receiving antenna, which is intended exclusively for receiving in the uplink. The antenna system 6th the base station 8th further comprises a line arrangement 17th over which the antennas 6a , 6b , 6c with the base station 8th are connected. It can be seen that the base station 8th two duplex filters for this purpose 19a , 19b and a receive filter 19c having. The first duplex filter 19a is with the transmitting and receiving antenna 6a connected, the second duplex filter 19b is with the transmitting and receiving antenna 6b connected and the receive filter 19c is with the receiving antenna 6c connected. Each of the four CHUs 41a until 41d is with each of the three antennas 6a , 6b , 6c connected and set up for this on the pair of frequency channels (carrier) assigned to the respective CHU via one of the antennas 6a , 6b , 6c Signals transmitted and through each of the antennas 6a , 6b , 6c To be able to receive signals.

Furthermore, from the 1 apparent that the surveillance system 21 a test facility 7th having a transmitter 13th and its own antenna 15th has that with the transmitter 13th connected is. The test facility 7th also has a memory 31 and a calculator 33 . The test facility 7th is designed in this embodiment as a modified subscriber station of the digital radio network and therefore for communication with the base station 8th furnished.

The test facility 7th is like that 1 can be recognized with an interface 25th the base station 8th connected. By one from the base station 8th generated and by the test facility 7th through the interface 25th received activation signal can be the test device 7th be activated and via a from the base station 8th generated and by the test facility 7th through the interface 25th received deactivation signal can be the test device 7th deactivated.

Furthermore, the monitoring system 21 in the in the 1 embodiment shown a processing device 23 on that with the base station 8th of the digital radio network 5 connected is. The processing facility 23 has a calculator 29 and a memory 27 .

In the 1 is also shown schematically that the test facility 7th for transmitting a test signal 11 by means of the transmitter 13th and the antenna 15th the test facility 7th is set up. This test signal 11 is from the base station 8th via the antenna system 6th the base station 8th receive.

The surveillance system 21 , especially the test facility 7th , the base station 8th and the processing device 23 of the monitoring system 21 , are for performing a method according to the invention for fault monitoring of the antenna system 6th the base station 8th furnished. In this exemplary embodiment, this is the test device 7th set up the base station to carry out steps a) and b) of the method 8th 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 described below with reference to FIG 2 explained in more detail. the 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 fault monitoring of the antenna system 6th the base station 8th of the digital radio network 5 by means of the test facility 7th .

In step a) of the exemplary embodiment explained here, the test device determines 7th first a target channel for the transmission of the test signal 11 . To this end, the test facility listens 7th a plurality of downlink frequency channels, the listened to downlink frequency channels are taken from a predetermined list, the downlink Contains frequency channels whose received power exceeds a predetermined minimum value. The test facility checks for each of the monitored downlink frequency channels 7th whether an MCCH is transmitted on this downlink frequency channel. On this basis, the test facility can 7th recognize whether the tapped downlink frequency channel to a main carrier of the TETRA trunked radio network 5 heard. 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 facility listens to the MCCH on every downlink frequency channel belonging to a main carrier and decodes the signaling information sent by the base station 8th be transmitted on the MCCH and a network operator of the radio network 5 Show. On this basis, the test facility can 7th check whether the base station transmitting the signaling information on the MCCH is the base station to be monitored 8th and on this basis ensure that the selected target channel is an uplink frequency channel used by the base station 8th is used for reception.

After the test facility 7th the target channel for transmitting the test signal 11 the test facility chooses 7th in step a) select a time slot on the target channel as a test signal time slot.

In the exemplary embodiment explained here, a linearization time slot is used for this purpose. The test facility 7th therefore first determines the linearization time slot on the target channel, ie it determines the position in time of the linearization time slot within the time-division multiplex structure of the target channel. For this purpose, the test device decodes 7th Signaling information received from the base station 8th be transmitted on an Access Assignment Channel (AACH) and display a linearization time slot, namely display a time slot that is assigned to the Common Linearization Channel (CLCH) of the TETRA standard.

The CLCH is a logical channel in the uplink of the TETRA standard. The temporal position of the CLCH, ie the temporal position of the time slot assigned to the CLCH, is indicated by the signaling information transmitted on the AACH. The test device selects the linearization time slot determined in this way 7th in step a) of the exemplary embodiment explained here as a test signal time slot.

The linearization time slot is a time slot which is repeated at time intervals specified by the time-division multiplex structure, as shown schematically in FIG 3 is shown. the 3 shows a time division multiplex structure 39a an uplink frequency channel and a time division multiplex structure 39b a downlink frequency channel of a digital trunked radio network according to the TETRA standard. The Indian 3 uplink frequency channel shown and the one in the 3 The illustrated downlink frequency channel 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 through the time division multiplex structures 39a , 39b the time in frames available on the respective frequency channel F1 to F18 is divided. 18 frames each F1 to F18 become a multiframe 35 summarized. Every single frame F1 to F18 comprises four time slots 37 who the timeslot numbers 1 until 4th (Timeslot Number, TN for short) are assigned. By combining a pair of frequency channels (uplink and downlink) and one of the four time slots 37 every frame F1 to F18 a physical channel is formed according to the TETRA standard, ie each carrier comprises four physical channels.

wobei TN die Zeitschlitz-Nummer (Timeslot Number) im Control Frame F18 und MN die Multiframe-Nummer (Multiframe Number) bezeichnen. Der Zeitschlitz des CLCH, d.h. der Linearisierungs-Zeitschlitz, ist im TETRA-Standard eigentlich dafür vorgesehen, dass die Teilnehmerstationen 9 in diesem Zeitschlitz eine Linearisierung ihrer Sender durchführen können.The Indian 3 also shown 18th frame F18 of each multiframe 35 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 4th ) 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 in the sense of the present invention. In the in the 3 The embodiment shown, the linearization time slot (ie the time slot of the CLCH) is the time slot 37 with the time slot number 2 in control frame F18 of the uplink frequency channel. According to the TETRA standard, the time slot varies 37 of the control frame F18, which is assigned to the CLCH and thus forms the linearization time slot, from multiframe to multiframe and results as $$\text{TN}=\mathrm{4th}-\left(\text{MN}+1\right)\text{mod}\mathrm{4,}$$

where TN denotes the timeslot number in the control frame F18 and MN denotes the multiframe number (multiframe number). The time slot of the CLCH, ie the linearization time slot, is actually provided in the TETRA standard for the subscriber stations 9 can perform a linearization of their transmitters in this time slot.

In addition, the test facility determines 7th in the in 2 illustrated step a) a reception power, ie a reception quality, one from the base station 8th transferred to and from the test facility 7th received downlink signal. For this purpose, the test device determines a received signal Strength Indicator (RSSI) of the received downlink signal.

In the 2 it is also shown that the test device then in step b) by means of its transmitter 13th and its antenna 15th the test signal 11 transmits. 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 used for the duration of the in 3 timeslot shown 2 transmitted in the control frame F18 of the uplink frequency channel of the main carrier.

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

Also in the 2 Step c) of the method according to the invention shown is the test signal 11 via the antenna system 6th from the base station 8th receive.

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

Steps b), c) and d) in the 2 The sequence of the method according to the invention, which is illustrated by way of example, is carried out with each repetition of the linearization time slot, ie with each repetition of the in 3 illustrated multiframes 35 , which contains a linearization time slot in control frame F18, is executed again. The base station determines each time steps b) to d) are repeated 8th thus a reception quality of the respectively received test signal in the form of an RSSI value and forwards each determined RSSI value to the processing device 23 further.

The processing device generates on the basis of the RSSI values determined in this way 23 in step e) of the in 2 An evaluation of the temporal course of the reception quality, 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 recognizes 23 depending on the evaluation of the chronological sequence, a fault in the antenna system 6th and, as a function of the evaluation of the chronological sequence, generates an output, that of the error monitoring of the antenna system 6th serves. A warning is generated as an output for the antenna concerned if the associated moving RSSI mean value falls below a predetermined first threshold value. In contrast, an alarm is generated as an output if the moving average falls below a predetermined second threshold value that 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 is the deviation for generating a warning 3 dB, while the threshold value of 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.

A reliable and precise fault monitoring of the antenna system is based on the described procedure 6th the base station 8th possible. It is advantageously possible to use each of the antennas 6a , 6b , 6c the antenna system 6th and each of the respective antenna 6a , 6b , 6c to monitor assigned connection line individually. In this way, the method according to the invention can be used to determine which antenna 6a , 6b , 6c the antenna system 6th and / or which associated connection line is affected by a possible error.

List of reference symbols

1, 2, 3, 4

Time slot number (TN)

5

digital radio network

6th

Antenna system

6a, 6b, 6c

Base station antennas

7th

Test facility

8th

Base station

9

Subscriber station

11

Test signal

13th

Test facility transmitter

15th

Test facility antenna

17th

Line arrangement

19a, 19b

Duplex filter

19c

Receive filter

21

Surveillance system

23

Processing facility

25th

Base station interface

27

Processing device memory

29

Processing facility computer

31

Test facility memory

33

Test facility computer

35

Multiframe

37

Time slot

39a, 39b

Time division multiplex structure

41a, 41b, 41c, 41d

Channel Unit (CHU)

43

Shelter

F1 to F18

Frame

Claims (31)

Method for error 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 the transmission of radio signals, the base station (8) 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), and each frequency channel has a time-division multiplex structure (39a, 39b) with time slots (37) following one another, with the following steps: a) Selecting 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) of the test device (7) via a antenna (6a, 6b, 6c, 15) connected to the transmitter (13) of the test device (7) is transmitted, c) receiving the test signal (11) by the base 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) detecting an error the antenna system (6) as a function of the reception quality of the received test signal (11), 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 the base station (8) received test signals (11) is generated and the output is generated as a function of the evaluation of the temporal course, wherein in step e) an error classification is carried out by the evaluation of the temporal course of the reception quality is compared with stored comparison data and in Depending on this comparison, a type of error is determined, and an output is generated containing information about the ermi includes the type of error. Procedure according to Claim 1 , characterized in that 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 a time slot (37) which 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). Procedure 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) can carry out a linearization of their transmitters in this time slot (37), with the time slot (37) which is selected as the test signal time slot in step a) and is used in step b) for the transmission of the test signal (11) is such a linearization time slot. Method according to one of the preceding claims, 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) which is assigned to a traffic channel in the time division multiplex structure (39a, 39b). Method according to one of the preceding claims, characterized in that the test device (7) in step a) of the method, like a subscriber station (9), is registered in a radio cell of the digital radio network (5) assigned to the base station (8), 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 an assigned time slot that the base station (8) of the registered test device (7) uses for transmission of radio signals. Procedure according to Claim 5 , characterized in that the test device (7) is registered in the radio cell assigned to the base station (8) with a priority which is lower than the priority of the other subscriber stations (9) registered in the radio cell. Method according to one of the preceding claims, characterized in that in step a) of the method the test device (7) listens to at least one of the frequency channels and thereby determines at least one free time slot which is assigned to a traffic channel in the time division multiplex structure (39a, 39b) and is currently not being used for a transmission of radio signals, 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), the free time slot determined in this way is. Method according to 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) via the antenna (15) of the test device (7) is transmitted. Method according to 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 of the antenna system (6) ) the base station (8), which is designed as a transmitting antenna or as a receiving antenna or as a combined transmitting and receiving antenna, the test signal (11) being transmitted via the first antenna in step b) and the test signal (11) being received in step c) is 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. Procedure according to Claim 9 , characterized in that the antenna system (6) has a plurality of antennas (6a, 6b, 6c) 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 (11) is received via the plurality of antennas (6a, 6b, 6c) set up for the reception of radio signals and - in step d) for each of the antennas (6a, 6b, 6c) set up for the reception of radio signals, an antenna-related reception quality of the test signal (11) received by 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. Procedure 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 test signal received by means of the respective antenna (6a, 6b, 6c) (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) ) the antenna system (6). Method according to one of the preceding claims, characterized in that in step a) the test device (7) determines 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). Procedure according to Claim 12 , characterized in that in step b) the test device (7) transmits a test message with the test signal (11), which can be decoded by the base station (8), the test message providing information about a reception quality, in particular a reception power contains downlink signals transmitted by the base station (8) and received by the test device (7). Method according to 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-division multiplex structure (39a, 39b) predetermined time intervals repeated, wherein at least steps b), c) and d) are carried out for each repetition or at least for some of the repetitions of the time slot (37). Method according to 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 the transmission of the test signal (11) and selects the test signal time slot on the target channel and in step b) the test device (7) determines the test signal (11) in the test signal time slot transmits on the target channel. Method according to 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. Method according to 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) which in the time division multiplex structure (39a, 39b) is not for communication between different stations of the digital radio network is provided and / or to determine the linearization time slot listens to at least one signaling channel of the radio network (5) and decodes signaling information that is transmitted by the base station (8) on the signaling channel. Method according to 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. Method according to 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 belonging to a common linearization channel (CLCH ) of the TETRA standard. Method according to 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 and / or selecting the target channel of the test signal time slot and / or to determine the linearization time slot - listens to a main control channel (MCCH) on at least one frequency channel and decodes signaling information that is transmitted by the base station (8) on the main control channel (MCCH), and / or - decoded signaling information which is transmitted by the base station (8) on an Access Assignment Channel (AACH). Method according to one of the preceding claims, characterized in that an output is generated in step e) which is used to monitor errors in the antenna system (6), with a warning being generated as an output if the reception quality and / or one derived from the reception quality Quantity meets a first condition, in particular falls below a predetermined first threshold value for 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 for the reception quality falls below, and wherein the second threshold value of the reception quality is smaller than the first threshold value of the reception quality. Procedure 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). Method according to 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) repeats at least one signaling channel of the radio network, in particular a main control channel (MCCH) of the TETRA Standards, 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) receives the downlink signals can no longer receive the intercepted 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. 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 used 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 the monitoring system (21) having a test device (7) which has one for a transmission of radio signals set up 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. 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 carrying out step e) or for carrying out Step d) and step e) of a method according to one of the preceding claims is set up. Monitoring system (21) Claim 24 or 25th , characterized in that the test device (7) and / or the processing device (23) and / or the monitoring system (21) are set up for fault monitoring of a plurality of antenna systems (6) of a plurality of base stations (8) of the digital radio network (5) . Test device (7) of a monitoring system (21) according to one of the Claims 24 until 26th . 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 through a to be activated by the base station (8) generated and received by the test device (7) via the interface (25) and / or by an activation signal generated by the base station (8) and from the test device (7) via the interface (25) received deactivation signal to be deactivated. Test device (7) Claim 27 or 28 , characterized in that the test device (7) is designed as a modified subscriber station (9) of the digital radio network (5). Base station (8) of a monitoring system (21) according to one of the Claims 24 until 26th . Computer program with program code means, set up to carry out a method according to one of the Claims 1 until 23 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 the Claims 24 until 26th and / or a computer (33) of a test device (7) according to one of the Claims 27 until 29 and / or a computer (29) according to a base station (8) Claim 30 and / or a computer of a processing device (23) of a monitoring system (21) according to one of the Claims 24 until 26th is.

Images