KR20070025277A - System for transmitting data through dmb network and method for error correction of transmitted data - Google Patents

Abstract

A system for transmitting data by using a DMB network and a method for error correction of the transmitted data are provided to retransmit data of a part where an error is generated when the error occurs in transmitted contents data to correct the generated error, thereby realizing fast transmission speed, improving the quality of the transmitted data, and enabling high-capacity data transmission. A method for transmitting data by using a DMB(Digital Multimedia Broadcasting) network comprises the following steps of: receiving a contents data transmission request through a mobile communication network or the DMB network from a DMB terminal(S410); extracting the requested contents data to transmit the contents data to the DMB terminal through the DMB network(S420); and extracting and retransmitting a part where an error occurs among the contents data if there is a retransmission request about an error part among the contents data transmitted through the DMB network or the mobile communication network from the DMB terminal(S440,S444,S446,S448).

Description

System for Transmitting Data through DMB Network and Method for Error Correction of Transmitted Data}

1 is a diagram briefly showing a data system using a DMB network according to an embodiment of the present invention;

2 is a block diagram schematically illustrating an internal configuration of a DMB terminal for performing data reception and error correction using a DMB network according to an embodiment of the present invention;

3 is a block diagram briefly illustrating an internal configuration of a content data providing server that is responsible for data transmission and data retransmission according to an error packet generation according to an embodiment of the present invention;

4 is a flowchart illustrating an error correction method of data using a DMB network according to an embodiment of the present invention.

The present invention relates to a data transmission system using a DMB network and an error correction method of transmission data. More specifically, the present invention relates to a content data transmission method of transmitting content data using a DMB network, and correcting an error caused by retransmitting data of an error portion when an error occurs in the transmitted content data.

With the rapid development of electronic and communication technology, various wireless communication services using a wireless telecommunication network have been provided. In particular, recently, DMB (Digital Multimedia Broadcasting) services, which are capable of providing high-definition television and video regardless of a place, are provided using a mobile receiver or a vehicle receiver such as a mobile communication terminal. DMB services are classified into satellite DMB and terrestrial DMB. Satellite DMB is a method of transmitting a DMB broadcast signal to a mobile receiver using a broadcast satellite, terrestrial DMB is a method of transmitting a DMB broadcast signal to a mobile receiver using a transmitter located on the ground.

The DMB network providing such a DMB service has a large bandwidth, a terrestrial DMB has a transmission speed of 0.8 Mbps to 1.7 Mbps, and the satellite DMB has a transmission speed of 2.4 Mbps, which has the advantage of transmitting high capacity data. In addition, when compared to a CDMA 1X EV-DO network or a network having a similar data transmission rate of a WCDMA network, data quality of the transmitted data is excellent according to the feature of transmitting data in one direction instead of a bidirectional signal.

However, the DMB network currently transmits only broadcast data generated by DMB stations. Accordingly, there is a demand for a technology for transmitting content data such as a ringtone, a video, and a photo by using a DMB broadcasting network having better performance than a mobile communication network.

On the other hand, when an error such as a part of the content data is broken or missing while receiving the content data from the Internet network using a cable, LAN line, telephone line, or the like, or wirelessly receiving the content data from the mobile communication network. There is. In the following description, a portion where such an error occurs is called an error packet.

When the content data including the error packet is received in this way, when the received content data is executed in the terminal, it may not be executed. Therefore, when an error packet is included in the transmitted data, a terminal receiving content data from an internet network or a mobile communication network that supports bidirectional communication may notify the fact that an error packet is generated and the error packet part to the Internet network or the mobile communication network. In addition, the error correction process of receiving the error packet generation part again should be performed.

On the other hand, the DMB network does not support bidirectional, but uses a method of transmitting broadcast data to the DMB terminal. Since the broadcast data used in the DMB network is reproduced immediately without executing the received data, even if error data is included, there is no problem in the screen reproduction or the audio reproduction for broadcasting.

Accordingly, in the DMB network, even if an error occurs while receiving broadcast type data, it is not necessary to be notified of the error occurrence and to perform the error correction process of receiving the retransmission.

In order to implement a content data transmission technology such as a ringtone, a video, and a photo by using the DMB broadcasting network, an error correction process for retransmitting an error packet generated in the data transmission process is urgently required.

In order to solve such a problem, the present invention transmits content data using a DMB network, and if an error occurs in the transmitted content data, the terminal determines whether an error packet is generated and the error packet information through the mobile communication network. The present invention provides a data transmission system using a DMB network and a method for correcting transmission data using a DMB network by transmitting a server to a server providing the data and re-receiving the data of an error portion through a mobile communication network.

In order to achieve the above technical problem, the present invention provides a data transmission method using a DMB network, and in the method of transmitting content data to a DMB terminal using a digital multimedia broadcasting (DMB) network and a mobile communication network, (a) a DMB terminal Receiving a content data transmission request from a mobile communication network or a DMB network; (b) extracting the content data requested for transmission and transmitting the extracted content data to the DMB terminal through the DMB network; And (c) extracting and retransmitting an errored portion of the content data when there is a retransmission request for an error portion of the content data transmitted through the DMB network from the DMB terminal through the mobile communication network.

In order to achieve the second technical problem, the present invention provides a method of correcting an error of content data, the method of correcting an error of content data transmitted through a digital multimedia broadcasting (DMB) network, comprising: (a) a DMB network; Receiving content data via; (b) requesting retransmission through the mobile communication network for the error portion of the received content data; (c) re-receiving the content data of the portion where the error occurs using the mobile communication network; And (d) combining the content data received in steps (a) and (c) and driving the content data.

In addition, in order to achieve the third technical problem, the present invention, as a content data providing server, a server for providing content data requested from a digital multimedia broadcasting (DMB) terminal using a DMB network and a mobile communication network, DMB terminal A content data request receiver for receiving a request signal for providing content data or a retransmission request signal for content data; A content data extraction unit for extracting all or part of the content data according to the provision request signal received from the content data request receiver or the retransmission request signal; And a content data transmitter for transmitting the content data extracted by the content data extractor using a DMB network or a mobile communication network.

In addition, in order to achieve the fourth technical problem, the present invention is a terminal for receiving content data through a DMB network, receiving content data through a digital multimedia broadcasting (DMB) network, and correcting an error in the received content data. A terminal comprising: a data receiving module for receiving content data transmitted through a DMB network and an error packet transmitted through a mobile communication network-data from which an error portion of the content data is extracted; A data error determination module for determining whether an error occurs in the content data transmitted through the DMB network and the error packet transmitted through the mobile communication network; A data transmission request module requesting retransmission of a portion where an error occurs in the mobile communication network; And a data integration module for combining the content data received through the DMB network and the error packet received through the mobile communication network.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

In addition, when a part is said to "include" a certain component, this means that it may further include other components, without excluding other components unless otherwise stated.

In addition, the term module described herein refers to a unit for processing a specific function or operation, which may be implemented in hardware or software, or a combination of hardware and software.

1 is a diagram schematically illustrating an error correction system according to data transmission using a DMB network according to an embodiment of the present invention.

The error correction system according to the present invention includes a DMB network 120, a mobile communication network 130, and a content providing system 140.

The DMB terminal 110 is a terminal that receives broadcast data and content data from the DMB network 120, and receives a bidirectional service such as voice call or data transmission and reception from the mobile communication network 130. The internal structure and function of the DMB terminal 110 will be described in detail with reference to FIG. 2.

The DMB network 120 is a network that provides broadcast data or content data to the DMB terminal 110 by using a DMB broadcasting station 122 and a relay device 124 such as a satellite, a terrestrial repeater, or a shadow area repeater.

The DMB broadcasting station 122 generates broadcast data and transmits the generated broadcast data through the relay device 124. In addition, it is connected to the content providing system 140, and receives the content data from the content providing system 140 and transmits it through the relay device 124.

The relay device 124 includes at least one of a satellite, a terrestrial repeater, and a shadow area repeater, and is a network terminating device for transmitting broadcast data or content data transmitted from the DMB broadcasting station 122 to the DMB terminal 110. In the satellite DMB network, a satellite and a shadow area repeater are used as the relay device 124, and in the terrestrial DMB network, a ground repeater and a shadow area repeater are used.

The mobile communication network 130 is a network for providing mobile communication services such as voice call service or data service to the DMB terminal 110, and includes IS-95A / B, CDMA 1X, WCMDA, EV-DO, EV-DV, GSM, It can be configured with various systems such as HSDPA and portable Internet. However, in the following description, the mobile communication network 130 will be described as being limited to the CDMA 1X network.

The mobile communication network 130 is a base station transmitter (BTS: hereinafter referred to as BTS) 132, a base station controller (BSC: hereinafter referred to as 'BSC') 134, mobile A communication switching center (MSC: Mobile Switching Center, hereinafter referred to as 'MSC') 136 and a Packet Data Serving Node (PDSN, hereinafter referred to as 'PDSN') 138.

The BTS 132 is a network termination device of a mobile communication network. The BTS 132 receives a voice call request, a content data providing request, an error packet retransmission request, etc. from the DMB terminal 110, and transmits an MSC 136 or a PDSN ( 138, and transmits the voice call and data call received through the BSC 134 to the DMB terminal 110 by wireless. In addition, the BTS 132 performs a location registration function of the DMB terminal 110 located in the cell area under its jurisdiction.

The BSC 134 controls a plurality of BTSs 132, allocates and releases radio channels for the DMB terminal 110, controls transmission output of the DMB terminal 110 and the BTS 132, and soft handoff between cells. And hard handoff determination, transcoding and vocoding, GPS clock distribution, and the like.

The MSC 136 performs basic and additional service processing, incoming and outgoing call processing of subscribers, location registration and handoff procedures, and interworking with other networks. In addition, including a home location register (HLR) and a visitor location register (VLR), the DMB terminal 110 requests location registration, and checks subscriber information to provide additional services.

The PDSN 138 transmits content data to the DMB terminal 110 using a packet data service. Accordingly, the PDSN 138 is connected to an additional service server located inside the mobile communication network 130 or a content providing server located outside the mobile communication network and connected through an internet network. The PDSN 138 is an evolution of an inter-working function (IWF) used to support data communication in a 2nd generation (2G) mobile communication system. It is also possible to use a manganese interlock device instead.

The content providing system 140 is a system for providing content data for an additional service provided to the DMB terminal 110 and includes a DMB broadcasting station 122 of the DMB network 120 or a PDSN 138 of the mobile communication network 130. Connected with

As described above, the content providing system 140 may include an additional service server located inside the mobile communication network 130 or a content providing server located outside the mobile communication network and connected through an internet network. In the following description, the additional service server and the content providing server will be collectively described as a 'content data providing server'.

The content providing system 140 includes a database 144 storing content data and a content data providing server 142 transmitting the content data stored in the database 144 to the DMB broadcasting station 122 or the PDSN 138.

The content data providing server 142 receives the content data providing request signal from the DMB terminal 110 through the PDSN 138, extracts the requested content data from the database 144, and generates the DMB network 120. If there is a retransmission request for an error packet generated from the content data transmitted from the DMB terminal 110, only the portion of the retransmission request is extracted from the database 144 to perform retransmission through the mobile communication network 130. Here, the internal structure and function of the content data providing server 142 will be described in detail with reference to FIG. 3.

As such, the DMB terminal receiving the content data through the DMB network 120 and performing error correction through the mobile communication network 130 determines whether an error packet occurs in the content data received through the DMB network and retransmits the error packet. It should include a function for recombining request and content data received through the DMB network and retransmitted content data.

2 is a block diagram briefly illustrating an internal configuration of a DMB terminal for performing data reception and error correction using a DMB network according to an embodiment of the present invention.

In order to receive content data and perform an error correction function using the DMB network 120, the DMB terminal 110 may include a DMB receiver 210, a microprocessor 220, a data storage unit 240, and a memory 250. , A key input unit 260, a screen display unit 270, a speaker 280, and an RF signal processor 290.

The DMB receiver 210 includes a DMB antenna and a DMB chip, and receives and transmits broadcast data or content data transmitted through a satellite, a terrestrial repeater, or a shadow area repeater to a microprocessor.

The microprocessor 220 controls the overall operation of the DMB terminal 110. That is, the service input request of the DMB terminal user is received through the key input unit 260, and among the programs stored in the data storage unit 240, a program providing the corresponding service is executed and executed, and the corresponding service is displayed on the screen display unit. 270 and speaker 280 to provide. In addition, when the service requested by the user is a service provided through the mobile communication network 130, accesses the mobile communication network 130 through the RF signal processing unit 290 and requests the provision of the corresponding service, and if the service is provided, the screen It is provided through the display unit 270 and the speaker 280. In addition, the voice data and the image data are separated from the broadcast data received through the DMB receiver 210 to display the image data through the screen display unit 270, and the voice data is transmitted through the speaker 280. .

In addition, when the content data transmitted using the DMB network 120 is received through the DMB receiving unit 210 according to the present invention, it is determined whether an error packet is generated, and when an error packet occurs, the mobile communication network 130 By transmitting the retransmission request signal for the error packet portion, and performs a function of re-receiving the content data for the error packet portion from the mobile communication network 130.

To this end, the microprocessor 220 is a data receiving module 222 for receiving content data transmitted through the DMB network 120, a data error determination module 224 for determining whether an error packet of the received content data occurs; The content providing system information determination module 226 for identifying the content providing system 140 that provided the received content data, the data transmission request module 228 for requesting retransmission of the content data for a portion where an error occurs, and the DMB network. And a data integration module 230 for integrating the content data received through the 120 and the content data retransmitted through the mobile communication network 130.

Here, the content providing system information determination module 226 checks the content providing system 140 transmitting the corresponding content data from the content data transmitted through the DMB network 120. To this end, the content providing system 140 transmits the content data to the DMB network 120 by including an identification ID or a URL address in the content data.

In this case, when the error packet of the content data received from the DMB terminal 110 is checked, the process of checking the content providing system may include a request for retransmission of a portion of the content data generated by the mobile communication network 130. It is necessary to access the content providing system 140 that provided the corresponding content data through.

The data storage unit 240 is a non-volatile memory having a high data processing speed and is associated with operating system (OS) software and a call processing having a real-time processing function for the operation of the DMB terminal 110. Store call processing software, etc. for processing functions.

In addition, the software for the interpretation of the received broadcast data and content data and the display of the DMB broadcast received through the broadcast data, and according to the present invention, receives the content data through the DMB network, and determines whether the error packet, Requesting retransmission, and storing software including a function of integrating the retransmitted content data with the content data received through the DMB network.

The memory 250 is an EEPROM (Electrically Erasable and Programmable Read Only Memory) that can erase or re-store electrically recorded data. The memory 250 stores data such as NAM (Number Assignment Module) parameters, telephone numbers, names, and short messages. Non-volatile memory to be written. According to the present invention, when the content data is transmitted through the DMB network 120, the information of the content providing system 140 confirmed by the content providing system information determination module 226 until the transmission of the content data is completed. It also serves as a temporary store.

The key input unit 260 is provided with a plurality of key buttons for inputting various data such as numbers and letters, so that a user may request various additional services through the key input unit 260. In addition, the key input unit 260 may be provided with a special key for viewing DMB broadcast.

The screen display unit 270 displays the operation status of the DMB terminal 110 including the reception strength, the date, and the time of the radio wave, and displays the received DMB broadcast or the provided content. The speaker 280 is a part for outputting a voice included in the DMB broadcast or the content when the DMB broadcast is displayed or when the content including the sound is played.

The RF signal processor 290 is a part that demodulates or amplifies an RF signal received from the mobile communication network 130 through an antenna, modulates or amplifies a signal generated from the microprocessor 220, and transmits the signal to the mobile communication network 130. .

At this time, the antenna for transmitting and receiving the RF signal for communication with the mobile communication network 130 and the DMB antenna for receiving broadcast data or content data transmitted from the DMB network 120 may be implemented as a single antenna, a separate Each may be implemented as an antenna.

The DMB terminal 110 configured as described above may receive content data provided from the content providing system 140 through the DMB network 120 or the mobile communication network 130.

3 is a block diagram schematically illustrating an internal configuration of a content data providing server that is responsible for data transmission through a DMB network and retransmission of data according to an error packet generation according to an embodiment of the present invention.

The content data providing server 142 of the content providing system 140 that transmits the content data through the DMB network 120 or the mobile communication network 130 includes a network interface card (NIC) 310 and a content data request receiving unit 320. , The content data transmitter 330, the content data extractor 340, and the database server 350.

The NIC 310 is a communication module that provides a communication interface for communicating with the DMB broadcasting station 122 of the DMB network 120 and the PDSN 138 of the mobile communication network 130.

The content data request receiver 320 is a part that receives a request for providing content data transmitted from the mobile communication network 130 through the PDSN 138. In this case, a request for providing the entire content data may be received, or a request for retransmission of the content data for some error packets among the content data transmitted through the DMB network 130 may be received.

When the content data requested from the DMB terminal 110 is extracted by the content data extractor 340, the content data transmitter 330 transmits the content data to the DMB network 120 or the mobile communication network 130 through the NIC 310. Play a role. At this time, the content data transmitter 330 may include a function of including the identification ID or URL address assigned to the content providing system in the content data so that the content providing system may transmit the content data from the DMB terminal 110. Perform.

The content data extractor 340 has a request for providing content data through the mobile communication network 130, extracts the corresponding content data from the database 144, and delivers the content data to the wireless data transmitter 330. In particular, when an error packet exists in the content data transmitted through the DMB network 120 and a retransmission request for the error packet portion is received from the DMB terminal 110, only the content data for the error packet portion of the content data is extracted. It plays a role.

The database server 350 controls the input, output, deletion, and modification of content data stored in the database 144. Here, the data may be input using the database server 350. For this purpose, the content data providing server 142 may further include an input unit, a display unit, and the like.

The content data providing server 142 configured as described above may be a server operated by a mobile communication service company or a server operated by a separate company. When operated by a mobile communication service provider, the mobile communication service provider may be located in the mobile communication network 130 and directly connected to the PDSN 138. When a separate company is operated, the DMB broadcasting station 122 and the PDSN 138 may be connected to the Internet network and a dedicated line. It may also be connected via, for example, to provide content data.

4 is a flowchart illustrating an error correction method of data using a DMB network according to an embodiment of the present invention.

A user who subscribes to the mobile communication service accesses the mobile communication network 130 using the DMB terminal 110 and requests the provision of content data such as a ringtone, a video, and a photo (S410).

The content data providing server 142, which is requested to provide content data through the mobile communication network 130, extracts the corresponding content data from the database 144 through the content data extracting unit 340, and transmits the content data transmitting unit 330. The identification ID or URL information of the content data providing server is inserted into the extracted data and transmitted to the DMB network 120.

The DMB broadcasting station 122 receiving the content data from the content providing system 140 transmits the content data to the DMB terminal 110 using the DMB channel through the relay device 124 such as a satellite, a terrestrial repeater, or a shadow area repeater. do.

The DMB terminal 110 downloads the content data transmitted from the DMB network 120 (S420) and checks whether an error packet exists in the content data received through the data error determination module 224. The identification ID or URL information of the content data providing server is also extracted from the content downloaded through the content providing system information determining module 226 (S430).

When the existence of the error packet is confirmed as a result of the data error check of the received content (S440), the RF signal processor 290 is connected to the mobile communication network 130 (S442).

The DMB terminal 110 connected to the mobile communication network 130 requests retransmission of an error packet among the received content data through the data transmission request module 228. At this time, by using the identification ID or the URL information confirmed by the content providing system information determination module 226, the content data providing server 142 to request retransmission of the content data is checked (S444).

The content data providing server 142, which has received the retransmission request for the error packet through the content data request receiver 320, extracts the requested error packet part from the database 144 through the content data extractor 340 ( S446), the content data transmitter 330 transmits the error packet extracted to the mobile communication network 130.

The DMB terminal 110 receives the content data transmitted through the mobile communication network 130 (S448), and checks the existence of an error packet again through the data error determination module 224 (S440). At this time, if an error packet exists again, the steps of S442 to S448 are performed again.

As a result of checking whether the error packet exists in the data in step S440, if the error packet does not exist, the DMB terminal 110 combines the received content data using the data integration module 230 (S450).

When the content data is combined, the content is driven to provide an additional service requested by the user such as a ringtone, a video, and a photo (S460).

Here, in the implementation of the present invention, when retransmission for the error packet is requested, the content providing system 140 is set to retransmit the error packet through the mobile communication network 130, but when retransmitting, the DMB network 120 again It is also possible to set to retransmit an error packet using.

The embodiments of the present invention described above are not implemented only through the apparatus and the method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Implementation may be easily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, error correction of content data transmitted through the DMB network can be performed. Thus, the content data through the DMB network has a high transmission speed, excellent quality of the transmitted data, and high data capacity. Can be transmitted.

Claims (12)

In the method for transmitting content data to a DMB terminal using a digital multimedia broadcasting (DMB) network and a mobile communication network, (a) receiving the content data transmission request from the DMB terminal through the mobile communication network or the DMB network; (b) extracting the requested content data and transmitting the extracted content data to the DMB terminal through the DMB network; And (c) extracting and retransmitting an error-prone portion of the content data when there is a retransmission request for an error portion of the content data transmitted through the DMB network from the DMB terminal through the mobile communication network; Data transmission method using a DMB network, characterized in that it comprises a. The method of claim 1, wherein step (b) And transmitting identification ID or URL information of a server providing the content data to the content data. The method of claim 1, wherein step (c) comprises: And retransmitting the content data requested to be retransmitted using the mobile communication network. A method of correcting an error of content data transmitted through a digital multimedia broadcasting (DMB) network, (a) receiving content data through the DMB network; (b) requesting retransmission through the mobile communication network for an error portion of the received content data; (c) re-receiving the content data of the portion where the error occurs using the mobile communication network; And (d) combining the content data received in steps (a) and (c) and driving the content data; Error correction method of the content data comprising a. The method of claim 4, wherein step (b) comprises: Extract identification ID or URL information of a server providing the content data included in the content data, and request retransmission of a portion in which the error occurs by accessing the server through the extracted identification ID or URL information; Error correction method for content data. The method of claim 4, wherein step (d) And when the error content is not included in the re-received content data, combining the received content data. A server for providing content data requested from a digital multimedia broadcasting (DMB) terminal using a DMB network and a mobile communication network, A content data request receiving unit configured to receive a request signal for providing the content data or a retransmission request signal for the content data transmitted from the DMB terminal; A content data extraction unit configured to extract all or part of the content data according to the provision request signal received from the content data request receiver or the retransmission request signal; And Content data transmission unit for transmitting the content data extracted by the content data extraction unit using the DMB network or the mobile communication network Content data providing server comprising a. The method of claim 7, wherein the content data transmission unit, And the identification ID or the URL information of the content data providing server is inserted into the content data extracted by the content data extracting unit. A terminal for receiving content data through a digital multimedia broadcasting (DMB) network and correcting an error in the received content data, A data receiving module configured to receive the content data transmitted through the DMB network and an error packet transmitted through the mobile communication network-data from which an error portion of the content data is extracted; A data error determination module for determining whether an error occurs in the content data transmitted through the DMB network and an error packet transmitted through the mobile communication network; A data transmission request module for requesting retransmission of the portion in which the error occurs to the mobile communication network; And Data integration module for combining the content data received through the DMB network and the error packet received through the mobile communication network A terminal for receiving content data via a DMB network, characterized in that it comprises a. The method of claim 9, wherein the terminal, Content providing system information determination module for identifying a content data providing server that has transmitted the content data Terminal for receiving content data via a DMB network, characterized in that it further comprises. The method of claim 10, The content providing system information determination module, And extracting identification ID or URL information of the content data providing server included in the content data, and confirming the content data providing server information. The method of claim 9, wherein the terminal, A DMB receiver for receiving content data transmitted through the DMB network; An RF signal processing unit for transmitting the request for providing the content data and the retransmission request signal and for receiving the error packet transmitted through the mobile communication network; Software having a function of determining whether an error occurs in the content data received through the DMB network, requesting retransmission of the portion where the error occurs, and combining the content data received through the DMB network and the retransmitted error packet. Data storage Terminal for receiving content data via a DMB network, characterized in that it further comprises.

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