WO2010094299A1

WO2010094299A1 - Method for operating a communication system, subscriber device, coordination node for a communication system, and communication system

Info

Publication number: WO2010094299A1
Application number: PCT/EP2009/001224
Authority: WO
Inventors: Jens Grebner; Sven Kerschbaum; Thomas Talanis; Frank Volkmann; Christoph Weiler
Original assignee: Siemens Aktiengesellschaft
Priority date: 2009-02-17
Filing date: 2009-02-17
Publication date: 2010-08-26

Abstract

The invention relates to a particularly powerful and a particularly robust method for operating a communication system, which comprises a coordination node and at least one subscriber device and is designed for the wireless data transmission using a time division multiplex method, wherein within the communication system synchronization signals (SK, ST1, ST2) are emitted at regularly recurring times (t1, t4, t6, t7, t9, t11) for the time synchronization of the subscriber devices. According to the invention, the coordination node emits synchronization signals of a first type (SK) at times of a first type (t1, t7, t9), and the subscriber device or one of the subscriber devices emits synchronization signals of a second type (ST1, ST2) at times of a second type (t4, t6, t11). The invention further relates to a subscriber device and to a coordination node for a communication system, and to a communication system.

Description

description

Method for operating a communication system, subscriber device and coordination node for a communication system and communication system

The invention relates to a method for operating a communication system having a coordination node and at least one user equipment and is designed for wireless data transmission using a time division multiplex method, wherein within the communication system for synchronization of the user equipment at regularly recurring times synchronization signals are sent out.

In general, in a time-division multiplexing process, which is also referred to as Time Division Multiplex (TDM) or Time Division Multiple Access (TDMA), data from different subscriber devices or network subscribers in certain time periods or time slots are transmitted on a shared channel. This requires a common time base of all user equipment, which is usually achieved by periodically transmitting synchronization signals through a coordination node, which is also referred to as a network master or gateway. These synchronization signals, also called "beacons" or "beacons", are used by the user equipment of the communication system for time synchronization.

A method of the type mentioned at the outset is known, for example, from the document "IEEE Std 802.15.4 - Standard for Information Technology - Telecommunications and Information Exchange between Systems - Local and Metropolitan Area Networks - Specific Requirements; Part 15.4: Wireless medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal Area Networks (WPANs), September 8, 2006 "In the known method, a coordination node in the form of the" coordinator "synchronization signals in the form of so-called These "beacons" allow subscriber devices of the wireless communication system to synchronize with respect to the superframe structure defined by the IEEE 802.15.4 standard. As a result, it is ensured within the scope of the time-division multiplexing method used that the subscriber devices carry out a data transmission at the correct time, ie within a time slot provided for this purpose.

Method for wireless data transmission using ei ^¬ nes time division multiplexing are becoming increasingly common. This also applies in particular to the use of appropriate methods or communication systems in the field of automation technology, ie, for example, for the wireless communication of sensors and actuators in an industrial plant. In this case, in comparison to other applications, particularly high demands are usually placed on the availability and the robustness of a corresponding method or communication system.

The present invention has for its object to provide a simultaneously very powerful and particularly robust method of the type mentioned.

According to the invention, this object is achieved by a method for operating a communication system which has a coordination node and at least one subscriber unit and is designed for wireless data transmission using a time division multiplex method, wherein Synchronization signals for temporal synchronization of the subscriber devices at regularly recurring times are transmitted, being sent at times of the first kind of synchronization signals Ie first type and sent out at times of the second type of the Teilnehmergerat or one of the Teilnehmergerate synchronization signals of the second kind.

The invention is based on the recognition that in terms of robustness, an essential aspect in operating a communication system is to ensure that all subscriber devices of the communication system are active or available. The prerequisite for this is generally, for example, that the power supply of the Teilnehmergerates is ensured, for example, by a functional Batte ^¬ rie that the Teilnehmergerat m range of the wireless communication system, ie in particular the coordination node of the communication system is located, and that the Teilnehmergerat to the communication ^¬ is connected, so that communication with the coordination node and / or other Teilnehmergeraten the communication system is possible.

Signals, for example in the form of data packets sent by a subscriber device within the communication system, are thus an indicator of the activity of the relevant subscriber device. It should be noted that, for example, in the case of subscriber devices in the form of sensors or actuators, these are frequently also in an idle state for a prolonged period in which they do not transmit any signals. This has the consequence that the activity state of a corresponding subscriber device on the part of the communication system, ie in particular of the coordination node of the communication Systems, can not be verified. This means that the coordination node or other subscriber devices of the communication system have no information as to whether a corresponding "silent" subscriber device is in an idle state or possibly not at all active, ie, for example, switched off or down Causes of a failure of a subscriber device, for example, consist in that the signal transmission within the wireless communication system is disturbed, the power supply of the relevant subscriber device has failed or the subscriber device is outside the range of the wireless communication system.

The method according to the invention is now advantageous in that, at times of the first type, synchronization signals of the first type are transmitted by the coordination nodes of the first type and synchronization signals of the second type are transmitted at times of the second type by the subscriber device or one of the subscriber devices. This offers the advantage that a synchronization signal of the second type transmitted by a subscriber device at the same time provides proof that the relevant subscriber device is still active and functional. This means that such a synchronization signal of the second type transmitted by a subscriber device or by one of the subscriber devices of the communication system simultaneously has the function of a "keep alive" signal Advantageously, this is done without additional transmission resources for this purpose of the communication system are required. The fact that it is possible to dispense with the separate transmission of "keepalive" signals or messages, advantageously further reduces the energy consumption of the subscriber devices or avoids an increase in the energy consumption of the subscriber devices by transmitting separate "keepalive" signals. Thus, the method according to the invention makes it possible to monitor the state of activity of the subscriber device or of the user device in a particularly simple and resource-saving manner

Subscriber devices of the communication system. As a result, the robustness of the method for operating the communication system or the communication system is advantageously increased, since a failure of a Teilnehmergerates can be detected quickly and reliably and almost no additional effort.

It should be noted that the synchronization signals of the first kind and the synchronization signals of the second kind need not necessarily be identical. On the one hand, this means that both the synchronization signals of the first type transmitted by the coordination node can differ from the synchronization signals of the second type transmitted by the subscriber device or the subscriber devices. On the other hand, the signals of the first type transmitted at times of the first type may also differ from one another and / or the signals of the second type emitted at times of the second type may differ from one another. Possible differences can hereby transmitted for example in the content time information given ^¬ if lying in the transmitted data and other information. The decisive factor is therefore ultimately that each of the synchronization signals of the first and second type is used for temporal synchronization of the communication system. It should be noted that in the context of the present invention, the wireless communication system can basically be a wireless communication system of any type. Preferably, the communication system is designed for wireless transmission by radio. In this case, any radio technologies can be used in which the data transmission takes place in accordance with a time division multiplex method. Examples of this are based on the standards IEEE 802.15.1, IEEE 802.15.4 or IEEE 802.11 based communication standards.

With regard to the manner of determining the sequence of times of the first and second type and determining which subscriber device transmits the synchronization signal of the second type at a time of the second type, various embodiments are conceivable.

In accordance with a particularly preferred embodiment, the method according to the invention is so pronounced that information is sent out by the coordination node with the synchronization signals of the first type as to which subscriber device is responsible for transmitting the synchronization signal of the second type or which at a subsequent time of the second type Subscriber devices are responsible for subsequent times of the second type in each case for the transmission of the synchronization signal of the second kind. This means that the control of the process in this case preferably lies solely with the coordination node, which simultaneously informs the subscriber device or subscriber devices with the synchronization signal of the first type transmitted by it at the time of the first type, that for transmitting a subsequent synchronization signal is or is. This means that the responsibility for sending out the synchro- In principle, it would be conceivable for the synchronization signal to be "passed on" from the relevant subscriber device to another subscriber device. However, in the sense of a central sequence control, it is advantageous if the determination of which subscriber device transmits the next synchronization signal or the next synchronization signals is preferably carried out exclusively by the coordination node.

As an alternative to the embodiment described above, the method according to the invention can advantageously also be configured such that the times of the second type are determined by the respectively competent subscriber device on the basis of a predetermined algorithm. Thus, a corresponding algorithm that determines when a synchronization signal of the first type is sent out by the coordination node and when and by which subscriber device a synchronization signal of the second type is determined or predetermined, for example, in the context of the configuration of the communication system. In this case, the corresponding sequence can advantageously be determined taking into account the respective circumstances, i. For example, the number of subscriber devices and their range, i. For example, the range of radio fields of Teilnehmergerate be set. By virtue of the fact that each subscriber device always knows whether and, if so, when, it is responsible for transmitting the second type of synchronization signal on the basis of the predetermined algorithm, advantageously a corresponding control on the part of the coordination node is unnecessary.

In a further particularly preferred embodiment, the inventive method is developed such that the synchronization signals of the second type comprise an identification identifying the respective transmitting subscriber device. This is advantageous because it enables a particularly simple and reliable check which subscriber device has transmitted the respective synchronization signal of the second type. It should be noted, however, that a corresponding identifier identifying the respective transmitting subscriber device is not absolutely necessary for an activity monitoring of the subscriber devices. If, for example, according to the preferred embodiment of the method according to the invention described above, the time points of the second type are determined according to a predetermined algorithm, it is already known within the communication system alone which subscriber device has transmitted the synchronization signal of the second type at a specific time of the second type.

In a further particularly preferred embodiment, the inventive method is so pronounced that is updated by the coordination node after receiving a synchronization signal of the second kind for the respective emitting Teilnehmergerat specific activity time stamp. This is advantageous since the information is available at any time for all subscriber devices on the part of the coordination node as to when the last time a signal was received by the relevant subscriber device. Preferably, updating of the specific for each ^¬ stays awhile emitting Teilnehmergerat Aktivitats- takes place in this case the time stamp even in the case that the part of the coordination onsknotens another signal, that is, for example, a data ^¬ signal or data packet has been received from the relevant Teilnehmergerat. This allows the part of the coordination node a Teilnehmergerat failed as inactive be ^¬ relationship as can be seen, if within a no signal has been received from this Teilnehmergerat predetermined period of time. Alternatively or additionally, it is the coordination node, however, also possible to detect the failure of a Teilnehmergerates directly to the absence of a synchronization signal of the second kind. Since the coordination node will usually know which subscriber device is responsible for transmitting the synchronization signal of the second type at a specific time, if one or more failures of a synchronization signal of the second type to be transmitted by this subscriber device can result in inactivity or failure of the synchronization signal Participants are closed.

Preferably, the inventive method is designed such that the reception of synchronization signals of the second type and / or transmitted by the subscriber device or the subscriber devices to the coordination node data signals is acknowledged by the coordination node by transmitting a confirmation signal. This embodiment is particularly advantageous in communication systems in which an acknowledgment of signals received by the coordination node is generally provided by the coordination node. Alternatively, in principle, however, a receiptless operation is possible.

In a further particularly preferred embodiment, the inventive method is further developed such that the confirmation signal is transmitted in conjunction with a synchronization signal of the first kind. In principle, it would be conceivable for the coordination node to acknowledge synchronization signals of the second type received by the subscriber devices in a separate time slot. The transmission of the confirmation signal in conjunction with one at a time The first type of synchronization signal transmitted first type is advantageous in that the use of an additional time slot for the transmission of the confirmation signal is avoided. Specifically, it is conceivable, for example, for a synchronization signal of the first type transmitted by the coordination node to comprise an array which contains an entry for each time slot or each subscriber unit which indicates, for example, the number of signals received since the last acknowledgment. Depending on the particular conditions and requirements, the acknowledged received signals here may either be only synchronization signals of the second type, only data signals or else both synchronization signals of the second type and also data signals.

In accordance with a further particularly preferred embodiment, the method according to the invention is configured such that a synchronization signal of the second type is supplemented by the transmitting subscriber device for diagnosis data relating to this subscriber device. This is advantageous because even if a subscriber device must permanently transmit data signals, ie, for example, productive data, to the coordination node during a time slot assigned to the data transmission, there is a possibility of supplying diagnostic data in the form of error messages to the coordination node transfer. Advantageously, this is possible without requiring the allocation of a further time slot or time segment to the relevant subscriber device. A corresponding additional allocation of a further time slot led to an increase in the latency, ie the cycle time. In addition, this would also lead to an increase in the energy consumption of the participating subscriber concerned, in particular in the case of Use of battery powered Teilnehmergeraten is disadvantageous.

Preferably, the inventive method can also be configured such that a synchronization signal of the second kind is received by a control unit. This offers the advantage that the operating device, which may be, for example, a so-called HMI (Human Machine Interface) device of an automation system, does not necessarily have to be in the range of the coordination node of the communication system to a synchronization signal of the communication system receive. If additional diagnostic data are transmitted by the transmitting subscriber device with the synchronization signal of the second type, the operating device is furthermore enabled to receive this diagnostic data directly from the relevant subscriber device.

Advantageously, the method according to the invention is furthermore so pronounced that the operating unit synchronizes in time with the communication system on the basis of the synchronization signal of the second type. This offers the advantage that the control unit access to the communication system and the transmission and in particular receiving data is made possible within the communication system, without necessarily a synchronization signal of the first kind must be received by the coordination node for the previous temporal synchronization. This is again advantageous, in particular, in those cases in which the operating device is in the range of one of the subscriber devices but not in the range of the coordination node.

The invention further relates to a subscriber device for a communication system, which has a coordination node and at least one Teilnehmergerat has and is designed for wireless data transmission using a time division multiplex method, wherein within the communication system for synchronization of the subscriber devices at regularly recurring times synchronization signals are sent out.

With regard to the Teilnehmergerates the present invention has for its object to provide a Teilnehmergerat of the aforementioned type, which supports a simultaneously very powerful and particularly robust method for operating the communication system.

According to the invention, this object is achieved by a subscriber device for a communication system which has a coordination node and at least one subscriber unit and is designed for wireless data transmission using a time-division multiplexing method, wherein synchronization signals are transmitted within the communication system for the time synchronization of the subscriber devices at regularly recurring times are formed, wherein the Teilnehmergerat is designed such that it receives synchronization signals of the first kind from the coordination node at times of the first kind and at times of the second kind either sends a synchronization signal of the second kind or receives a synchronization signal of the second kind from another subscriber device of the communication system.

The advantages of the subscriber device according to the invention essentially correspond to the advantages of the method according to the invention, so that in this regard reference is made to the corresponding explanations given above. The same applies with regard to the below-mentioned preferred developments of the subscriber device according to the invention in each case with regard to the corresponding preferred development of the method according to the invention, so that reference is also made in this regard to the corresponding respective statements in this respect in this regard.

Preferably, the subscriber device according to the invention is designed in such a way that it receives information from the coordination node with the synchronization signals of the first type which subscriber device is responsible for transmitting the synchronization signal of the second type at a subsequent time of the second type or which subscriber devices at subsequent times of the second type each responsible for the transmission of the synchronization signal of the second kind.

According to a further particularly preferred embodiment, the subscriber device according to the invention is designed to determine the times of the second type on the basis of a predetermined algorithm.

Preferably, the subscriber device according to the invention can also be designed in such a way that it is designed to transmit a synchronization signal of the second type comprising a identifier identifying the subscriber device.

According to a further particularly preferred embodiment, the subscriber device according to the invention is designed such that it is designed to receive a confirmation signal transmitted by the coordination node and acknowledging the reception of synchronization signals of the second type and / or of data signals transmitted by the subscriber device or subscriber devices to the coordination node. Advantageously, the subscriber device according to the invention is designed such that it is designed to receive the acknowledgment signal in conjunction with a synchronization signal of the first type.

Advantageously, the subscriber device according to the invention can also be developed in such a way that it is designed to supplement a synchronization signal of the second type with diagnostic data relating to the subscriber device.

In principle, the subscriber device can be a subscriber device of any type and function. According to a particularly preferred embodiment, the subscriber device according to the invention is a sensor or an actuator of an automation system. This is advantageous since, especially in the field of industrial automation, wireless communication systems are becoming increasingly widespread and in this case particularly high demands are placed on robustness and performance. In particular, in the event that the subscriber devices in the form of sensors or actuators have no wired or line-bound power supply but are each supplied by a primary cell, for example, the aspect of operating the subscriber board as energy-efficiently as possible is of great importance.

The present invention furthermore relates to a coordination node for a communication system, which has the coordination node and at least one subscriber unit and is designed for wireless data transmission using a time-division multiplexing method, wherein synchronization signals are transmitted within the communication system for the time synchronization of the subscriber units at regularly recurring times. With regard to the coordination node, the present invention has for its object to provide a coordination node of the type mentioned, which supports a simultaneously very powerful and particularly robust method for operating the communication system.

According to the invention, this object is achieved by a coordination node for a communication system which has the coordination node and at least one subscriber unit and is designed for wireless data transmission using a time-division multiplexing method, wherein synchronization signals are transmitted within the communication system for the time synchronization of the subscriber units at regularly recurring times, wherein the coordination node is designed such that it transmits synchronization signals of the first type at times of the first type and receives synchronization signals of the second type from the subscriber device or one of the subscriber devices at times of the second type.

The advantages of the coordination node according to the invention in turn essentially correspond to those of the method according to the invention, so that reference is made in this regard to the corresponding statements. The same applies with regard to the following preferred developments of the coordination node according to the invention in relation to the corresponding preferred developments of the method according to the invention.

Advantageously, the coordination node according to the invention can be designed in such a way that the coordination node is formed with the synchronization signals of the first type for transmitting information about which subscriber device has a second time for the second Sending the synchronization signal of the second type is responsible or which subscriber devices are responsible for subsequent times of the second kind respectively for the transmission of the synchronization signal of the second kind.

According to a further particularly preferred embodiment of the coordination node according to the invention, the coordination node is designed to determine the times of the second type on the basis of a predetermined algorithm.

Preferably, the coordination node according to the invention can also be developed in such a way that the coordination node is designed to receive a synchronization signal of the second type comprising a identifier which identifies the respective transmitting subscriber device.

Advantageously, the inventive Koordinationskno ^¬ th is so pronounced that the coordination node Sieren upon receipt of a synchronization signal of the second type for a specific updated for the respective emitting Teilnehmergerat Aktivitats time stamp is formed.

In accordance with a further particularly preferred development, the coordination node according to the invention is embodied such that the coordination node is designed to transmit a confirmation signal acknowledging receipt of synchronization signals of the first type and / or of data signals transmitted by the subscriber device or subscriber devices to the coordination node.

Advantageously, the inventive Koordinationskno ^¬ th is such further developed in that it is designed for transmitting the Bestatigungssignals in conjunction with a synchronization signal of the first type. In accordance with a further particularly preferred development, the coordination node according to the invention is designed to evaluate diagnostic data received with a synchronization signal of the second type and relating to the transmitting subscriber device.

The invention further comprises a communication system for wireless data transmission using a time-division multiplex method with at least one inventive subscriber device or at least one subscriber device according to one of the previously described preferred developments of the subscriber device according to the invention as well as with a coordination node according to the invention or a coordination node according to one of the above described preferred developments of the inventive coordination node.

In the following the invention will be explained in more detail by means of exemplary embodiments. This shows

Figure 1 in a schematic sketch to explain an exemplary embodiment of the inventive method on a frequency channel of a communication system signals transmitted as a function of time and

2 shows a schematic sketch to explain an exemplary embodiment of the inventive communication system, a representation of the range of the radio fields of a coordination node and Teilnehmergeraten the communication system. FIG. 1 shows, in a schematic sketch to explain an exemplary embodiment of the method according to the invention, signals transmitted on a frequency channel of a communication system as a function of time t. In this case, synchronization signals S and data signals D, for example in the form of data packets or data frames, can be seen in FIG. By the respective index K, Tl or T2 is hereby illustrated whether the signal in question from the coordination node or a first or a second Teilnehmergerat is sent out.

The synchronization signals S are used in particular for temporal synchronization of subscriber devices of the communication system. This means that the synchronization signals S have the function of a "beacons" or "beacons" within the communication system.

In the illustration of FIG. 1, it can be seen that synchronization _signals of the first type S _K are emitted by the coordination _node of the communication system at times of the first type t 1, t ₇ and t ₉ . In addition, at times of the second type t ₄ , t _ß and tu synchronization signals of the second kind S _T i, S _{T2 are} transmitted from the first or second subscriber device of the communication system. Further, in Figure 1 the data signals D _τ i and Dτ ₂ indicated that t at time points _2, t _3, t _5, te and tio be transmitted from the first Teilnehmergerat or the second Teilnehmergerat to the coordinator node of the communication system.

Characterized that at points in time of the second type t _4, te, tu synchronization signals of the second type S _τ i, S _T2 are transmitted from the subscriber Advised each other participating devices and in particular the coordination node of the grain are communication system advantageously informed that the relevant Teilnehmergerat is in an active state. This means that at times the second type ti, te and tu transmitted synchronization signals of the second type S _T i, S _T 2 in addition to the time synchronizers ^¬ tion furthermore also the function of a "Keep Alive" fulfill signal. Advantageously, in this case, a corresponding Proof of the activity of the relevant subscriber device without the need for a separate signal to be transmitted from the subscriber device concerned to the coordination node This is particularly advantageous in those cases in which a time slot assigned to the respective subscriber device is permanently required for the transmission of data signals to the coordination node It should be noted that the communication system is usually more than two

Subscriber devices will have and thus often no additional free time slots for the transmission of a separate "Keepalive" signal will be available.

When a Teilnehmergerat for emitting a synchronizers ^¬ tion signal of the second type is be competent, can be communicated to _κ by the coordination node of the communication system with a synchronization signal of the first type S him on the one hand. On the other hand, it is also possible that the instants of the second kind, to which the respective Teilnehmergerat for transmitting the synchronization signal of the second type S _{τ ι,} S _T is be competent 2, of the relevant Teilnehmergerat basis of a vorbe ^¬ agreed algorithm are determined. Depending on the respective characteristic, it is advantageous if the synchronization signals of the second type S _T i, S _T2 emitted at times of the second type t ₄ , te, tu comprise an identifier identifying the respective transmitting user equipment. This advantageously allows the coordination node to monitor the activity of the subscriber get the synchronization signals of the second kind S _T i, S _T2 in a particularly simple way.

Since the coordination node will be generally known, however, that _τ of the subscriber devices at a given time of the second type for transmitting the synchronization signal, second S i, S _T2 is be competent, an appropriate, the respective emitting Teilnehmergerat identifying identifier but not mandatory. Based on the synchronization signals of the second type S _T i, S _τ2 received at times of the second type, it is possible for the coordination _node to check the activity of the respective subscriber _device . This can be done, for example, by updating an activity timestamp specific to the respective subscriber device. An updating of the respective activity time stamp is preferably also carried out in the event that a data signal Dτi or D _T 2 is received from the first or the second subscriber device by the coordination node.

According to the representation in FIG. 1, there is basically the possibility that synchronization signals of the first type S _K and synchronization signals of the second type S _τ χ, S _{τ 2 are transmitted} with different frequencies. On the one hand, this relates to the frequency with which synchronization _{signals of the} first kind S _κ are emitted in comparison with synchronization _{signals of the} second type S-ri, S _τ2 . On the other hand, the subscriber devices of the communication system can also be responsible for the transmission of a synchronization _{signal of the} second type S _τi , S _{T2 at} different times. Thus, it is conceivable, for example, for a subscriber _device whose functionality and activity is of particularly great significance to be particularly responsible at times of the second type for the transmission of synchronization _{signals of the} second type S _τi , S _τ2 . at Such a subscriber device may be, for example, a sensor or an actuator of an automation system, which serves for detecting or influencing a variable which is particularly critical for a production process.

Insofar as a stand-alone operation takes place within the communication system, no further measures are required in this regard in an implementation of the method according to the invention. In the event that received signals or packets are to be acknowledged by the coordinator node, which may also be referred to as a gateway or must, on the one hand the possibility that the coordination node of the subscriber Advised received data signals D _τ i, D _T2 and / or received Synchronization _{signals of the} second kind S _T i, S _{τ2 acknowledged} in a separate time slot. Furthermore, it is also conceivable that the coordination _node all received data signals D _T i, D _τ2 and / or all received synchronization signals of the second kind S _T i, S _T 2 in the form of a so-called "group acknowledgment" in a synchronization signal emitted by him the first type S. _κ confirmed depending on the particular design of the communication system and the exact procedure can this be desirable or necessary under certain circumstances that the coordination node, the synchronization signals of the first type S _κ compared to the light emitted from the subscriber Advised synchronization signals of the second type S _T i, S _T2 emits more frequently, ie that times of the first kind ti, t ₇ , t ₉ occur more frequently than times of the second kind t _4f tβ, tu, where the frequency in which the coordination node expediently sends corresponding confirmation signals is dependent on the time respective application, ie in particular, in which time intervals an acknowledgment ge ^¬ sent signals from the Teilnehmergeraten is expected. FIG. 2 shows, in a schematic sketch to explain an exemplary embodiment of the communication system according to the invention, a representation of the range of the radio fields of a coordination node as well as of subscriber devices of the communication system. In detail here are the ranges or the spatial coverage of the radio field R _{κ of} the coordination node of the communication system and the radio _{fields of} a first Teilnehmergerates R _τi , a second Teilnehmergerates R _T2 and a third Teilnehmergerates R _T3 shown, the radio fields for simplicity as circular to the respective , centered component have been adopted.

Furthermore, the range R _{HMI of} an operating device in the form of a so-called HMI (Human Machine Interface) device for operating and monitoring the communication system is also shown in FIG. In general, it is advantageously possible for a synchronization signal of the second type transmitted at a time of the second type to be supplemented by the respective transmitting subscriber device for diagnosis data relating to this subscriber device. Advantageously, therefore, the Bediengerat as shown in Figure 2 diagnostic data, such as in the form of parameters or so-called log files received by the second Teilnehmergerat with the radio field R _τ2 , although the Bediengerat at the relevant time not within the radio range R _κ of Koordina ^¬ tion node of the communication system halt. This is made possible by the fact that the operating device uses a time-based synchronization signal of the second type received by the second subscriber device at a time of the second type

Synchronization with the communication system can make. Thus, there is the possibility of a direct, ie not mediated via the coordination node, communication between the Bediengerat and the second Teilnehmergerat. That's it For example, also conceivable that the operating device sends a request to the second Teilnehmergerat with the request to request data about in the form of diagnostic data, from the first Teilnehmergerat with the radio field R _n . As an alternative to such a direct establishment of contact, a corresponding data transmission on the part of the second subscriber device can also be initiated via the coordination node of the communication system.

It is further apparent from FIG. 2 that the first subscriber unit, whose radio field or the range or spatial extent of its radio field is denoted by R _τ i, and the third subscriber unit with radio field R _T3 are not in mutual range, ie the range or radio coverage the respective radio _fields R _τl and R _T3 does not overlap. This leads to the fact that the first subscriber device can not receive synchronization signals of the second type transmitted by the third subscriber device. Conversely, this applies correspondingly to the third subscriber device with respect to synchronization signals of the second type transmitted by the first subscriber device. Even if such a situation should occur in practice, this is usually not a problem, since the subscriber devices of the communication system can usually keep the time synchronization independently over a certain period of time. Since the coordination node, is advantageously arranged so that it lies within the reach of all participating devices, which means that his radio field R _κ to each of the hops R _tL, R _T2, Rτ lapped ₃ of the subscriber devices uber-, this means that the subscriber devices, the time synchronization up to the next from the Koordinati ^¬ onsknoten sent synchronization signal of the first kind automatically, without receiving a further synchronization signal must hold. Due to its central arrangement within the communication system, the coordination node receives all the transmitted synchronization signals of the second type as well as all other data signals sent by the subscriber devices in the respective time slots. In this context, it should be noted that the coordination node at times of the second type preferably also synchronizes with respect to the respective received synchronization signal of the second type.

It should be noted that in the described method, in principle, a small time offset may occur, but does not lead to a disturbance. The cause for a corresponding time offset is that the clocks of the network subscribers, i. of the coordination node and the participant's equipment, which in practice usually differ slightly. However, this skew usually occurs only at the level of communication on which the described method operates, i. usually at the MAC (Media Access Control) level, a role. This means that, for example, communication or protocol levels responsible for communication and application are not affected, since these are synchronized independently of this, for example as part of a packet exchange.

According to the above statements, the invention is particularly advantageous in that a particularly simple and resource-saving monitoring of the state of activity of subscriber devices of the communication system is made possible. This advantageously increases the robustness of the method for data transmission or of the communication system. There is also beneficial ^¬ way legally possible to transfer that emitted in the ter at times two ^¬ kind of the participants Advised synchronization signals of the second type in addition diagnostic data become. A further advantage is that for a control unit of the communication system, a subscriber device, such as in the form of a sensor or actuator, is immediately "visible", without this necessarily before a communication with the coordination node of the communication system is required.

Claims

claims

1. A method for operating a communication system having a coordination node and at least one Teilnehmergerat and is configured for wireless data transfer using a time division multiplex process, wherein (within the communication system for time synchronization of the subscriber devices to periodically recurring time points ti, t _4, xo, t ₇ , tg, tu) synchronization signals (S _κ , S _τ i, S _T2 ) are emitted, characterized in that - are transmitted at the times of the first kind (ti, t ₇ , tg) from the coordination node synchronization signals of the first kind (S _κ ) and - At times of the second type (t ₄ , te, tu) of the Teilnehmergerat or one of the Teilnehmergerate synchronization signals of the second kind (S _T i, S _T2 ) are sent out.

2. The method according to claim 1, characterized in that from the coordination node with the synchronization signals of the first kind (S _κ ) information about which subscriber device at a subsequent time second type (t ₄ , t ₆ , tu) for transmitting the synchronization signal second type (S _T χ, S _T 2) is responsible or which user equipment at subsequent times of the second type (t ₄ , t _δ , tu) in each case for the transmission of the synchronization _{signal of the} second kind (S _T i, S _τ2 ) are competent.

3. The method according to claim 1, characterized in that the time points of the second type (t ₄ , t ₆ , tu) are determined by the respectively competent subscriber device on the basis of a predetermined algorithm.

4. The method according to any one of the preceding claims, characterized in that the synchronization signals of the second type (S _τ i, S _τ2 ) _comprise an identifier identifying the respective transmitting Teilnehmergerat.

5. The method according to any one of the preceding claims, characterized in that is updated by the coordination node after receiving a synchronization signal of the second kind (S _T i, S _T 2) for the respective emitting subscriber device specific activity time stamp.

6. The method according to any one of the preceding claims, characterized in that the reception of synchronization signals of the second kind (S _τ i, S _T2 ) and / or transmitted by the Teilnehmergerat or the subscriber devices to the coordination node data signals (D _T1 , D _T2 ) by the Coordination node is acknowledged by the transmission of a confirmation signal.

7. The method of claim 6, characterized in that the confirmation signal in connection with a synchronization signal of the first kind (S _κ ) is transmitted.

8. The method according to any one of the preceding claims, characterized in that a synchronization signal of the second type (S _T i, S _T2 ) is supplemented by the transmitting subscriber device for diagnosis data relating to this subscriber device.

9. The method according to any one of the preceding claims, characterized in that a synchronization signal of the second kind (S _T i, S _T2 ) is received from a Bediengerat.

10. The method according to claim 9, characterized in that the control unit based on the synchronization signal of the second kind (S _τ i, S _T2 ) synchronized with the communication system in time.

11. Teilnehmergerat for a communication system having a coordination node and at least one Teilnehmergerat and is designed for wireless data transmission using a time division multiplex method, wherein within the communication system for time synchronization of the subscriber devices at regularly recurring times (ti, tu, t _δ , t ₇ , tg, tu) synchronization signals (S _κ , S _τ i, S _T2 ) are emitted, characterized in that the Teilnehmergerat is designed such that it

- Receives synchronization signals of the first kind (S _κ ) from the coordination node at times of the first kind (ti, t ₇ , tg) and

- At times of the second kind (t ₄ , t ₆ , tu) either - a synchronization signal of the second kind (S _T i, S _τ2 ) emits or - _Receives a synchronization _{signal of the} second kind (S _T i, S _τ2 ) from another subscriber device of the communication system.

12. Subscriber device according to claim 11, characterized in that the subscriber device is designed such that it receives from the coordination node with the synchronization signals of the first kind (S _κ ) information about which subscriber device at a subsequent time second type (t ₄ , tβr tu) is responsible for the transmission of the synchronization signal of the second type (ST _I , S _T2 ) or which subscriber devices at subsequent times of the second type (t ₄ , t ₆ , tu) respectively for the transmission of the synchronization signal of the second type (S _τ i, S _T 2) are competent.

13. Teilnehmergerat according to claim 11, characterized in that the Teilnehmergerat for determining the times of the second kind (t ₄ , tβ, tu) is formed on the basis of a predetermined algorithm.

14. Subscriber device according to one of claims 11 to 13, characterized in that the Teilnehmergerat for transmitting a the Teilnehmergerat identifying identifier comprehensive synchronization signal of the second kind (S _T1 , S _K ) is formed.

15. Subscriber device according to one of claims 11 to 14, characterized in that the subscriber device for receiving a transmitted from the coordination node, the reception of synchronization signals of the second kind (S _τ i, S _T 2) and / or by the participant mergerat or the subscriber devices at the coordination _node transmitted data signals (D _τl , D _T2 ) acknowledgment acknowledgment signal is formed.

16. Subscriber device according to claim 15, characterized in that the subscriber device for receiving the confirmation signal in conjunction with a synchronization signal of the first kind (S _κ ) is formed.

17. Subscriber device according to one of claims 11 to 16, characterized in that the subscriber device for supplementing a synchronization signal of the second kind (S _τ i, S _T2 ) is formed around the Teilnehmergerat diagnostic data.

18. Subscriber device according to one of claims 11 to 17, in that a subscriber device is a sensor or an actuator of an automation sys tem.

19. coordination node for a communication system which has the coordination node and at least one subscriber device and is designed for wireless data transmission using time-division multiplexing, wherein within the communication system for time synchronization of the subscriber devices at regularly recurring times (ti, t ₄ , t _β , t ₇ , tg, tu) synchronization signals (S _κ , S _τ i, S _T 2) are emitted, characterized in that the coordination node is designed such that it - at times of the first kind (ti, t ₇ , tg) synchronization signals of the first kind (S _κ ) sends out and - At times of the second type (t ₄ , t _f tu) synchronization signals of the second type (S _T i, S _T 2) from the Teilnehmergerat or one of the subscriber devices received.

20. coordination node according to claim 19, characterized in that the coordination node is formed with the synchronization signals of the first kind (S _R ) for transmitting information about which subscriber device at a subsequent time second type (tu, t ₆ , tu) for the transmission of the synchronization signal second type (S _τ i, S _T 2) is responsible or which subscriber devices are responsible for subsequent times of the second type (t ₄ , tβ _r tu) respectively for the transmission of the synchronization _{signal of the} second kind (S _τi , S _T2 ).

21. coordination node according to claim 19, characterized in that the coordination node for determining the times of the second type (t ₄ , tβ, tu) is formed on the basis of a predetermined algorithm.

22. coordination node according to one of claims 19 to 21, characterized in that the coordination node for receiving exnes a the respective transmitting subscriber device identifying identifier comprehensive synchronization signal of the second kind (S _τ i, S _τ2 ) from ^{¬ is} formed.

23. coordination node according to one of claims 19 to 22, characterized in that the coordination node upon receipt of a synchronization signal of the second kind (S _T i, S _T2 ) for updating a for the respective sending subscriber specific activity time stamp is formed.

24. coordination node according to one of claims 19 to 23, characterized in that the coordination node for transmitting a reception of synchronization signals of the second kind (S _τ i, S _T2 ) and / or transmitted by the Teilnehmergerat or the subscriber devices to the coordination node data signals (Dτi D _T2 ) acknowledgment acknowledgment signal is formed.

25. coordination node according to claim 24, characterized in that the coordination node for transmitting the confirmation signal in conjunction with a synchronization signal of the first kind (S _κ ) is formed.

26. coordination node according to one of claims 19 to 25, characterized in that the coordination node for evaluating with a synchronization signal of the second kind (S _T i, S _τ2 ) received, the transmitting Teilnehmergerat diagnostic data is formed.

27. A communication system for wireless data transmission using a time division multiplex method with at least one Teilnehmergerat according to one of claims 11 to 18 and a coordination node according to one of claims 19 to 26.