Method of transmitting data in a packet-oriented data network

The invention relates to a method for packet-oriented Transmission of data between at least two communication devices, according to the preamble of claim 1 and a control device and a conversion device.

are communication links for transmission of speech up to date connection oriented predominantly. To this end, is for signal transmission between two communication endpoints only a physical connection provided which reserved for the entire duration of the connection is. This is also called circuit-oriented transmission, static Routing (circuit switching) or circuit-switching designated.

With the advent of packet-oriented data networks (packet switching) such as the Internet, is in the fixed network in comparison to the connection-oriented telecommunications reduced cost of communication available. This is mainly due to the efficient capacity utilization a compound, because in contrast to the circuit-switching the packet switching not for the entire duration of the connection the physical transmission medium is busy. The to transporting data is divided into individual data packets, wherein each data packet with an address code, of the Recipient of the transmission features. The individual data packets are then transmitted independently - this they can even use different transmission paths. The Principle of packet switching in various standards defined, the most well-known standard is specified in ITU-T Recommendation x.25 described.

are as packet-oriented transmission method for language For example VoFR (Voice over Frame Relay) or VoIP (Voice over IP) are known. This voice data are digitized, a source coding and channel coding preferably a subjected and divided into data packets, which then via the Internet are received. In particular, VoIP is an essential Importance for future voice communication predicted. Here, the speech is digitized and via Hardware or software compression (source coding), the compressed speech then the payload portion of the IP packets represents. Outgoing calls are converted into IP addresses, which are used as destination information in the IP header. about multiple, distributed in the data network nodes are now the IP packets transported to the far end of the voice connection. The remote station stores the incoming packets and converts them back together in the correct order. Becomes a package damaged or lost it, so it will not send again. On the other side is the packets the extracted speech information, which is then a coding device is supplied in which the information then inverse source- and is channel encoded and then on appropriate Hardware is made audible.

Since a delayed arrival of adjacent IP voice packets (Delay) adversely affect the quality of the voice connection effect, are in the IP network, various methods for time synchronization, and thus to minimize the delay, provided adhere to a QoS (Quality of Service). To This method includes integrating a Real-Time Protocol (RTP) in which each IP packet, inter alia, an additional Timestamp (timestamp) with the time of origin and a Sequence number (Sequence information) obtained. This allows the Receiver means, packages not only in the correct order, but also assemble synchronously. also defined RTP coding of audio signals according to G.723, G.711 or G.729. This is to Enkodierungsund Decoding method (codec) that for the ITU analog and digital encryption of speech in telephone networks have been defined. G.711 approximately corresponds to the ISDN standard, wherein the speech data / S can be transmitted with a data stream of 64 kbit. By additional source code can be the data rate up to 9.6 kbit / s (corresponding to the GSM standard) reduce, allowing only a transmission over VoIP networks becomes.

These processes include the widespread CELP method (Codebook Excited Linear Predictive Coding), which with a complicated mathematical model of human language is working. At the output of source coding is a data stream with a data rate of 16 kbit / s, wherein the speech quality almost ISDN voice quality equivalent. Combined with a defined in G.723 standard Dual Rate Speachcoding, satisfies even a data stream with a data rate of only 5.3 kbit / s accepted subjectively at a reduced but Voice quality. Besides bringing a lower network load this means that multiple IP packets buffered the further advantage are, without jeopardizing the real-time condition. The quality the voice transmission in IP data network thus increases with decreasing Data rate for a speech channel.

Voice over IP also includes protocols for transmitting different Multimedia formats on audio only go out. In particular, subject to this extension, the Ability to transfer video conferencing. Among the best known codecs for source coding of video signals is one of the MPEG-1 standard. Here, the resolution the image to be encoded to a source input format (SIF) limited, in which the chrominance sub-sampled in both directions is and halved the number of pixels becomes. By means of motion estimation and redundancy reduction the moving picture data reduced so that a transfer is made possible by the IP network. A widely used standard for source coding of moving image material presents the adopted in 1990 by the CCITT H.261 standard is. Was developed this compression standard for video conferencing and other video services in ISDN at bit rates of multiples of 64 kbit / s. Later the improved and expanded H.263 standard was developed, for the smaller bit rate 64 kbit / s has been specified.

For each category of data (audio or video), there is therefore a Many of its own codecs. For communication must of course all potential communication partners each Codec, with which a message was encoded dominate, a subsequent decoding to perform. For example, a voice message with the audio codec G.729 encoded and transmitted to a receiving device, which this codec can not decode, so the connection is canceled.

With the increasing spread of different VoIP networks and application scenarios are increasingly being special Equipment for use which govern only specific coding. In such network configurations would therefore have a Variety of standard devices, a growing number of coding be implemented, what more computing power and higher royalty costs due.

The invention is therefore based on the object, a method further develop the generic type to the effect that also with differently styled coding and decoding techniques, a connection is established. Furthermore it is an object of the invention, a controller and a Conversion means for performing the method for To make available.

This object is achieved by a method having the features of Patent claim 1 and by a control device according to claim 9 or by through a conversion device Claim 10 dissolved. Preferred embodiments of the invention result from the dependent claims.

Refer to "Multimedia data" in the context of the invention Voice data and / or image or moving image and video data Roger that.

An essential idea of ​​the invention is that the to be transmitted multimedia data with mutually incompatible Encoding and decoding method of a transmitting and Receiving device to the first communication device transmit a vorgesehenene in the data network conversion device, converted within the conversion device, and the converted multimedia data to the transmission and Receiving means of the second communication device be transmitted.

An advantage of this method lies in the fact that a Connection even with mutually incompatible coding and decoding method of the terminals are effected can. Thus, less coding methods are important part the terminals integrated, whereby the device's internal computing power be reduced for performing the encoding can. In addition, cost of licenses, for execution encoding the necessary software or hardware is reduced.

In a preferred embodiment, by means of an inside a controller arranged monitoring device one due to incompatible coding and decoding techniques not executable in connection. Then, a first marking to a likewise within the controller arranged signaling device transmitted. The transmitted signaling device thereon a signaling on the second communication device, by means of which a search of within the Decoding means of the second communication device decorated decoding process is initiated. in the Connection of this query is a second marking which depending on the inside of the decoding means furnished decoding method is, to the control device transmitted and then to the conversion device transmitted. is within the control device the encoding method of the first communication device characterized and to a respective third marking the conversion device transmits. Subsequently the multimedia data within the conversion device in response to said second and third marking converted.

In a further embodiment, by means of a within the Conversion means arranged monitoring device one due to incompatible coding and decoding techniques not executable in connection. Then, a first marking to a likewise arranged within the conversion device Signaling device transmits. The signaling device transmitted on a signaling to the second communication device by means of a query the decoding means within the second communication device decorated decoding method is initiated. Following this inquiry is the second communication device a second label, the function of the inside of the decoding means decorated decoding method is, the conversion device transfer. Within the conversion device is the encoding process of the first communication device in the third marking. Subsequently, the multimedia data is also here within the conversion means in response to the second and third marking converted.

Preferably to be converted multimedia data a converting means disposed inside the supplied third decoding device which according the second marking a decoding of the coded multimedia data performs. The decoded multimedia data on a likewise within the conversion unit fed arranged third coding unit according to the third identification coding of Multimedia data performs. Following conversion the coded data to the transmitting and receiving device transmitting the second communication device.

To convert the conversion device holds in a software-based design within a database a Plurality of algorithms for performing Dekodierungsund Coding method stored. One with the database via an interface connected processor executes accordingly received from the control unit the second and third Marking a decoding and encoding at the same time the Data.

In a hardware-based implementation which are to be converted Multimedia data within a conversion device arranged semiconductor element, in particular a Digital Signal Processor (DSP), are fed. The data then within the DSP's function of the second and the third marking converted.

In a preferred embodiment, the data network as a communication system according to the standard H.323 for transmitting built VoIP data and the control means is preferably formed as an H.323 gatekeeper. In another Embodiment, the data network as a multimedia communication system constructed according to a SIP standard, wherein the control means is then preferably configured as a SIP proxy. Preferably, the conversion means through the Controller means of the H.248 protocol or the Megaco protocol (MGCP) driven.

Further advantageous embodiments result from the Dependent claims and the following description of the preferred Embodiments, the reference to the figures are explained in detail. In the figures:<sl><li>Fig. 1 shows a construction of a communication system according to standard H.323,</li><li>FIG. 2 shows a structure of an H.323 network,</li><li>Fig. 3 shows an example of a network construction in an embodiment the invention,</li><li>Fig. 4 shows an example of a signaling sequence based on a Flowchart,</li><li>FIG. 5 shows an example of a converting device,</li><li>Fig. 6 shows an example of a control device and</li><li>Fig. 7 shows an example of a communication device.</li></sl>

1 shows a system structure is shown by standard H.323. The H.323 standard is the standard for real-time communication and describes the transport of multimedia data via IP-based networks that do not have guaranteed "Quality of Service" (QoS) have. A real-time protocol (RTP) defines the encoding of audio signals and video signals. For each of these categories of data has its own codecs, which are also standardized. Which codec in communication is used depends on the available resources (Computing power, transmission bandwidth) and the desired Quality from and is set upon connection.

For the transmission of audio data are the codecs G.711, G.723 or G.729 involved to source coding. In particular, the Standard G.723 comes to VoIP transmission of great importance , since the output of a source code for this Standard, a data stream with a data rate of 5.3 kBit / s is available with good voice quality. to transfer of moving image material on VoIP networks, the video data compressed by the codec H.261 or H.263. Here comes in particular the H.263 standard of great importance, since this codec, the video data to a data rate less than 64 kbit / s compressed.

Fig. 2 shows the structure of an H.323 network. In a H.323 network there are several different components: Terminals, gateways, gatekeepers, and multipoint control units (MCU). Terminals are in H.323 Recommendation endpoints a bi-directional real-time communication. H.323 defines the different modes found on the terminals together and share information. For information, exchanged between H.323 terminals, include audio / video data and control signals. For each of these Data categories have their own codecs that also standardized are.

In the gateways of the transition from one transmission network is in another and the associated conversion between different transmission formats. are gateways mainly for the connection of the public telephone network used on the Internet.

A gatekeeper is responsible when connecting the Access permissions the user to check, address translations perform and available for communication manage bandwidth. The collection of all terminals, gateways and multipoint control units, which manages a gatekeeper, called H.323 zone.

In a conference call between three or more H.323 terminals or gateways is a Multipoint Control Unit required. An MCU consists of a Multipoint Controller (MC) and any number of Multipoint Processors (MP).

Fig. 3 shows an example of a network construction in an embodiment the invention. In this example, would a mobile Users of a mobile network - here a GSM network - A GSM-IP gateway to connect to an IP-network build up. The mobile subscriber provides to a mobile radio terminal 1 over an air interface, a compound a Base Transceiver Station (BTS) 2 ago. The connection is composed of the cellular network via the GSM IP gateway 3 to IP network routed.

The IP network is in this embodiment as H.323 / H.248-controlled built VoIP network. The GSM-IP gateway 3 sets the GSM-encoded voice signals to IP packets. from that it follows that the speech signals also in the VoIP network according to the GSM coding are encoded. The embodiment is continue on the assumption that all calls of all participants a control device 4, for example a H.323 gatekeeper, are signaled. One with the VoIP network connected terminal 5 has only the coding G.723 integrated. In relation to the prior art can Thus, between the mobile terminal 1 and the terminal 5 no Voice channels are established.

According to one embodiment of the invention is within the VoIP network conversion device 6 is integrated. These Device contains a monitoring device which a Occurrence of a rejected due to incompatible codec Connection acknowledges. Thereupon signaling For sensing the by the mobile terminal 1 and the terminal 5 codecs triggered. The conversion means 6 holds a plurality of codecs stored by means of which the encoded data of the mobile radio terminal 1 is decoded, then according to the codec of the terminal 5 again are encoded and then transmitted to the terminal 5 will.

This method is also carried out, of course, vice versa, so that the encoded according to G.723 data of the terminal 5 are decoded, and then according to the GSM standard, again be encoded and to the GSM-IP gateway 3 and then are transmitted to the mobile station first As generic control protocol between the conversion device 6 and the H.323 Gatekeeper 4 is the standard H.248 uses.

Fig. 4 shows an example of signaling sequence between two communication devices 7, 7 'with reference to a flowchart. builds a subscriber A from the mobile network with the GSM-IP gateway 3 a reputation in the VoIP network to the terminal 5 a subscriber B on. Since the GSM-IP gateway 3 am Interworking can only ship GSM-encoded voice data, is only this format in a H.225.0 SETUP message given to the H.323 gatekeeper 4th This indicated that the Available language format and forwards the SETUP message to subscriber B on. Subscriber B responds with a H.225.0 ALERT message specifying the implemented Language formats such. BG723.

The gatekeeper 4 now recognizes the lack of a common Language format and now causes in turn the structure of corresponding voice channels in the conversion device 6 via H.248 messages. When this is done, the ALERT message concerning the destination address of voice data modified by Party A and to the calling subscriber A passed. Thus, the GSM-IP gateway 3 is caused its user data not to the terminal 5, but the conversion means 6 to send. Furthermore, this Time also already known at which port number conversion means 6 sent the voice data of subscriber B Need to become. This is, for example, by means of a H.225 signaling facility message to the terminal. 5 Thereby is the terminal 5 does not cause its user data to the GSM-IP gateway 3 but to the conversion device 6 to send.

Once in the course participant B using a H.225 CONNECT message to the gatekeeper 4 to establish the connection concludes, on the one hand this is to the GSM-IP gateway 3 passed. On the other hand on the gatekeeper 4 the Voice channels active in the conversion device 6, whereby now the voice data relating to the language in the formats Converting means 6 implemented for this call.

Figure 5a shows an example of converting means 6 according to an embodiment of the invention. Within the conversion device 6, two databases 8, 8 'is arranged. The first database 8 holds a variety of algorithms stored to the decoding data, the second database 8 'holds a plurality of algorithms for encoding data stored. The data to be converted to a first Processor 9 is supplied. Between the processor 9 and the control means 4 is a H.248 connection is established, via the second label concerning the codecs supplied Data is transported. In accordance with this marking is an algorithm for from the first database 8 Loading decode this data and then decoding performed.

The decoded data is then a second processor 9 ', respectively, which is also an H.248 connection to the Control means 4 has, on the said third marking transported with respect to the codec of the called terminal 5 becomes. According to this marking is of the Coding Necessary codec from the second database 8 'loaded and a coding performed. The coded data a transmitting device 10 supplied that will transmit the data transmits, to the respective terminal.

Fig. Figure 5b shows in an exemplary embodiment of the invention another structure of a converting means 6 '. In contrast to the embodiment shown in Fig. 5a are within the device only one processor 9 '' and a database 8 "arranged for implementing the method. The Database 8 "contains algorithms for decoding and at the same time encoding data. According to the above H.248 line markings transferred is from the database 8 ", a suitable codec loaded by means of which the Processor 9 '' which the processor data supplied in accordance decodes the second marking and at the same time according to the third marking to be coded. The coded Data transmitting means 10 'is supplied, this data then transfers to the respective terminal.

Fig. Figure 6 shows in an exemplary embodiment of the invention a configuration of a control device 4. The device be via a first and a second H.225-transceiver device 11, 11 'signaling data to establish a Connection between two devices supplied. The data be a arranged inside the device 4 monitor 12 fed to the one due to incompatible Encoding and decoding method rejected Connection and registered on a first marking transmits to a signaling device. 13

The signaling means transmits via the second H.225-transmission and Receiving means 11 'signaling to query the furnished within the second terminal decoding method. Depending on a signaling obtained back signaling of the second terminal A second marking depending on the inside the second terminal furnished decoding method in. Depending on a signaling structure signaling the first terminal obtained A third marking depending on the inside the first terminal furnished coding method in. The second and third indicia a H.248 transmitting and receiving device 15 to the converting means transfer.

Figure 7 illustrates a communication device 7, consisting from a terminal 5, the above lines with a coding device 16 and a decoding device 17 connected is. The facilities are provided with a H.225 transmitting and receiving device 11 'connected to the incoming forwards it to the decoding means 17th In an embodiment not shown in the diagram, are the decoding means 17, the coding device 16 and the H.225 transmitting and receiving device 11 " integrated within the terminal. 5 Instead of a terminal may also include a VoIP-configured personal computers be used.

The embodiment of the invention is not limited to the Examples and highlighted above aspects limited but in the scope of the claims as well as in a variety of modifications possible within the scope of expert action.