JP2009044485A - Data transmission apparatus and content distribution system - Google Patents

Abstract

A data transmission apparatus and a content distribution system capable of high-speed and high-reliability data distribution from a distribution server to a passenger terminal in a distribution system using power line communication and capable of broadcast communication without delay at the time of PA, etc. provide.
When downloading content data to all SEBs by unicast communication with a built-in LPF inside the SEB, each SEB is separated in a network, and at the same time, content data transmitted from a server device 100 is stored in the SEB. Transfer sequentially to the next stage via the built-in memory. Further, at the time of multicast communication, the PA notification is transmitted to all passenger terminals without delay by turning off the LPF function.
[Selection] Figure 1

Description

  TECHNICAL FIELD The present invention relates to data transmission for transport such as an aircraft, and in particular, a data transmission device that distributes video, audio, and information data via a power line to a plurality of terminal devices arranged in a passenger seat and the like. The present invention relates to a content distribution system.

  In content distribution systems installed in airplanes and trains, weight reduction of wiring is an important issue. In recent years, wireless communication systems such as IEEE802.11a / b / g are becoming widespread, and a wired LAN (Local Area Network) using Ethernet (registered trademark) for distribution services of contents such as video and audio in an aircraft. A technique for using a wireless LAN system instead of the system has been proposed (see, for example, Patent Document 1).

  That is, in a plane, a wireless LAN system is arranged, and content data is sent to the wireless terminal devices installed in each passenger seat, thereby forming a content distribution system and reducing wiring cables. Yes.

  In recent years, power line communication (PLC) technology that uses a home power line as it is for communication has appeared as a method for connecting home devices. If this power line communication system is used for a content distribution system in an aircraft, a content distribution system can be configured without a new wiring as in the case of a wireless communication system.

However, power line communication has a narrower transmission band than Ethernet (registered trademark) or the like, and it is difficult to simultaneously distribute a large amount of data such as video data to many passenger terminals. It is also difficult to divide the network using a switching hub or the like as in Ethernet (registered trademark) to reduce the bandwidth per network. 2. Description of the Related Art Conventionally, a technique has been proposed in which a power line network inside and outside a building is separated by an LPF (Low Pass Filter) to prevent interference between networks and efficiently use the transmission bandwidth of the power line (see, for example, Patent Document 2). ).
JP 2006-506899 A JP 2006-237820 A

  However, the content distribution system using the conventional wireless LAN described in Patent Document 1 described above has a problem that communication becomes unstable due to a change in the radio wave environment in the aircraft.

  Moreover, although the conventional example described in Patent Document 2 described above discloses that the power line network inside and outside the building is separated by the LPF, this technique assumes a relatively low-rate signal such as a control signal. No specific method for efficiently performing data transmission between networks in a system that requires high speed and high reliability, such as a content distribution system, is disclosed. Furthermore, in-flight services in the aircraft include, for example, in-flight announcements for all passengers and cautions and explanations for emergencies in addition to the VOD service that provides content in response to passenger requests, such as the content distribution service described above. Broadcast communications such as certain PA (Passenger Address) or emergency broadcasts that require immediacy occur. In such a case, there is a problem that the contents and information are not immediately transmitted to passengers. It was.

  The present invention has been made to solve the above problems, and in a distribution system using power line communication, it is possible to distribute data from a distribution server to a passenger terminal at high speed and stably, and broadcast communication without delay at the time of PA or the like. An object of the present invention is to provide a data transmission device and a content distribution system capable of performing the above.

  In order to solve the above-described problem, a data transmission device according to claim 1 of the present invention is a data transmission device that transmits data by superimposing frequency on a power line, the memory storing data, and the memory Between the first power line adapter and the second power line adapter, and the controller that controls writing and reading of the data, the first power line adapter and the second power line adapter that superimpose or separate data on the power line The filter that passes the commercial power frequency and blocks the data superposition frequency and the data extracted from the first power line adapter are written to the memory, and the written data is read and superimposed on the power line by the second power line adapter And a control unit. As a result, the communication bandwidth of the power line can be used efficiently, and high-speed and stable data transmission becomes possible.

  The data transmission device according to claim 2 of the present invention is the data transmission device according to claim 1, wherein the control unit determines whether the data is transmitted by unicast communication or multicast communication. And a function for controlling whether or not to insert a filter based on the determination result of the determination unit. Thereby, efficient power line communication is possible for each of unicast communication and multicast communication.

  The content distribution system according to claim 3 of the present invention includes a plurality of data transmission devices according to claim 1 connected in cascade to a distribution server via a power line, to a request of a passenger terminal connected to the data transmission device. Accordingly, a content distribution system that provides at least one data of video, audio, and information stored in the distribution server to the passenger terminal, the distribution server transmits the data to the unicast communication prior to the request from the passenger terminal. Are sequentially transmitted to all data transmission apparatuses, and the data transmission apparatus stores data in a memory. Thereby, in the content distribution system using power line communication, it is possible to download content data to the memory of the data transmission device at high speed and stably using unicast communication that can be retransmitted.

  The content distribution system according to claim 4 of the present invention is the content distribution system according to claim 3, wherein the data transmission device transmits data to the next data transmission device before the data is completely stored in the memory. May be transferred. Thereby, content data can be downloaded to all data transmission apparatuses in a short time.

  According to a fifth aspect of the present invention, there is provided a content distribution system in which a plurality of data transmission devices according to the second aspect are connected to a distribution server in cascade via a power line, and a passenger terminal connected to the data transmission device is requested. Accordingly, the content distribution system provides at least one data of video, audio and information stored in the distribution server to the passenger terminal, and the distribution server distributes the data to the data transmission device by unicast communication or multicast communication. When the data is distributed by unicast communication, the filter of the data transmission device is inserted, and when the data is distributed by multicast communication, the filter is not inserted. Thus, when using unicast communication, all data transmission devices are separated from each other in a network to effectively use the communication band, and when using multicast communication, all data transmission devices are combined into one network. Connect and distribute information to all passenger terminals without delay.

  In the content distribution system according to claim 6 of the present invention, in the content distribution system according to claim 5, the distribution server may transmit the PA information to the data transmission apparatus by multicast communication. Thereby, PA information can be simultaneously distributed to all passenger terminals.

  The content distribution system according to claim 7 of the present invention is the content distribution system according to any one of claims 3 to 6, and when an error occurs in unicast communication, the MAC is used for power line communication. It is desirable to resend. As a result, retransmission that is faster and more stable than retransmission at the TCP / IP layer is possible.

  According to the present invention, in a distribution system using power line communication, a data transmission apparatus and a content distribution system that can perform high-speed and stable data distribution from a distribution server to passenger terminals and can perform broadcast communication without delay at the time of PA, etc. Can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a data transmission apparatus and a content distribution system using the same according to Embodiment 1 of the present invention. In the present embodiment, an example in which the present invention is applied to an IFE (In Flight Entertainment) system in an aircraft will be described.

  As shown in FIG. 1, the content distribution system of the present embodiment includes a server device 100 for storing and processing content data such as video and audio for distribution and notification, and devices constituting the content distribution system. An AC power supply 106 for supplying power, a power line 107, a PLC adapter 105, and a SEB (Seat Electric Box) that serves as a data transmission apparatus connected to the server apparatus 100 in cascade via the PLC adapter 105 and the power line 107 108, SEB109, and SEB110. In the content distribution system according to the present embodiment, a case where n SEBs are provided is shown, and these SEBs are arranged under a passenger's seat or the like. Further, three passenger terminals 111, 112, and 113 each having a monitor as a main component are connected to SEBs 108, 109, and 110, respectively. Of course, the number of passenger terminals is not limited to three.

  With such a basic configuration, the content distribution system according to the present embodiment enables a VOD (Video on Demand) service that provides content such as movies and music programs desired by passengers at desired times. In the present embodiment, in response to a request from the passenger, the content is not directly distributed from the distribution server device 100 to the passenger terminal, but all the content to be distributed is previously stored in the SEB 108, 109, 110 from the distribution server device 100. A VOD service is realized by downloading in advance to a content storage memory (not shown). That is, when the passenger specifies content that the passenger wants to enjoy from the passenger terminal, the specified content is reproduced from the SEB and output to a monitor or the like. The content download may be performed while the aircraft is parked, for example. In this way, a service that requires transmission of a large amount of data, such as a VOD service, is realized using power line communication with a narrow transmission band.

  In addition, unlike services such as VOD, immediacy is required when reporting to all passengers at the same time without delay, such as during emergency broadcasts for all passengers, or at the time of PA (Passenger Address), which is a precaution or explanation for emergencies. In-flight announcement service is also realized.

  In order to implement such communication services as content distribution and in-flight announcements, in the content distribution system of the present embodiment, first, the server apparatus 100 stores a unicast server 101 for storing, processing, and distributing VOD content. And a multicast server 102 for simultaneously making in-flight announcements for all passengers, a switch 103 for switching between unicast service and multicast service, and a switch control unit 104 for controlling switching of the switch 103.

  Here, a communication method for transmitting data to a specific partner is called unicast communication, and a communication method for simultaneously transmitting data to a plurality of unspecified many partners is called a multicast communication method. If unicast communication is used, it is necessary to transmit data as many as the number of parties, so a large transmission band is required. Even if an error occurs during communication and data does not reach a specific party, Since it is possible to retransmit only the other party that did not arrive due to an error, highly reliable communication is possible. In communication such as Ethernet (registered trademark), the retransmission mechanism is generally implemented by a protocol such as TCP in the transport layer (fourth layer) of the OSI reference model. The MAC layer that is the data link layer (second layer) is equipped with a mechanism, and by using the retransmission mechanism in this MAC layer, it is implemented at a lower layer, so the processing load is lighter, faster and more stable Re-transmission is possible. Note that even when both retransmission in the MAC layer and TCP retransmission are used, the reliability is higher and is not excluded from the scope of the present invention.

  On the other hand, in the multicast communication method, data cannot be retransmitted, but the same data can be transmitted without delay at the same time, and the data can be transmitted only once, so the transmission band can be small.

  In the server apparatus 100, the unicast server 101 stores content data that is a target of the VOD service, such as video data and audio data such as movie programs and music programs. Then, all contents targeted for VOD are distributed in advance to the SEBs 108, 109, and 110 while the aircraft is parked.

  Moreover, in the server apparatus 100, the multicast server 102 implements a simultaneous service for all passengers. That is, since the multicast server 102 performs services for a plurality of opponents, that is, all passengers, for example, it stores emergency content to be used before takeoff and content data of a PA that is an explanatory matter, etc. It processes live images outside the aircraft during landing and real-time audio such as in-flight announcements. Thus, the video and audio data generated by the processing of the multicast server 102 are transmitted to the SEBs 108, 109, and 110 as necessary.

  The PLC adapter 105 is a converter for receiving data from the distribution server device 100 via, for example, an Ethernet (registered trademark) line and converting the received data into data for power line communication. The PLC adapter 105 may be built in the server device 100.

  The SEBs 108, 109, and 110 temporarily store the content data distributed from the distribution server device 100 and sequentially transmit the content data to the subsequent SEB. At the same time, the SEBs 108, 109, and 110 To provide. Although not shown, a low-pass filter that passes the commercial power supply frequency but cuts off the PLC signal frequency is built in, and the front and rear SEBs are separated in a network by this low-pass filter. This enables the distribution server to transmit the content to all SEBs by unicast communication even with a narrow bandwidth power line. The configuration and operation of this SEB will be described in detail later.

  Passenger terminals 111, 112, and 113 are monitors and headphones (not shown) for viewing video and audio content that passengers want to enjoy using the VOD service, and for viewing broadcast services such as PA. It is composed of

  As described above, in the content distribution system according to the embodiment of the present invention, a VOD service using unicast communication or an emergency PA service using multicast communication can be used while using power line communication with a narrow band.

  Next, the internal configuration and operation of the SEBs 108, 109, and 110 will be described in detail. 2 and 3 are a block diagram showing the internal structure of the SEB 108 and a signal flow. FIG. 2 shows a signal flow during unicast communication, and FIG. 3 shows a signal flow during multicast communication. The SEBs 109 and 110 have the same configuration and operation as the SEB 108, and will be described as a representative of the SEB 108. In FIG. 2, the SEB 108 extracts and controls the memory 203 that stores the content data transmitted from the distribution server, the control unit 204 that controls the operation and data flow of the SEB 108, and the PLC data transmitted from the power line. A PLC adapter 201 for outputting to the unit 204, a PLC adapter 202 for superimposing data from the control unit on the power line 107, and a low-pass filter connected between the two PLC adapters 201 and the PLC adapter 202. An LPF 205 is provided. The LPF 205 is a low-pass filter having a cutoff frequency that allows the commercial power supply frequency to pass but cuts off the carrier signal for PLC communication. Further, the LPF 205 is configured to be able to turn on / off the filter characteristics upon receiving a command from the control unit 204.

  First, a case where VOD content is downloaded to all SEBs by unicast communication will be described with reference to FIG. In FIG. 2, a one-dot chain line 206 and a two-dot chain line 207 indicate the flow of content and power signals, respectively. A dotted line 208 indicates the flow of an analog video signal or an analog audio signal that flows in the wiring connecting the SEB 108 to the passenger terminal 111.

  Since the content data transmitted from the unicast server 101 of the server apparatus 100 via the power line 107 is blocked by the LPF 205, the content data is not directly transferred to the next-stage SEB 109 but extracted by the PLC adapter 201, and the control unit The data is written into the memory 203 via 204. The content data stored in the memory 203 is simultaneously transferred to the next-stage SEB 109 (not shown). Similarly, the content data stored in the memory of the SEB 109 is transferred to the next SEB, finally transferred to the SEB 110, and the storage of the content data in the memories in all the SEBs is completed. This operation is often performed before passenger service such as when the aircraft is parked, but is not limited to parking, and it goes without saying that it may be performed, for example, during a flight.

  Then, when the passenger boarded and arrived at the passenger seat, at that time, the passenger selected the content to be viewed and played back from the memory in the SEB arranged under the passenger seat, and the passenger terminal arranged in front of the passenger seat You can enjoy content on other monitors. At this time, the content data is transmitted through the power line. However, since the power line, which is a communication path between the SEBs, is separated by the LPF 205, it is possible to use all bands for one SEB. In other words, in this embodiment, the PLC network to which all the SEBs are connected is separated by terminating each low-pass filter for each SEB, and data transmission between each SEB is performed in a bucket relay manner via a memory. Since all communication bands can be occupied by one SEB, it is possible to download a large amount of data at high speed and stably compared to the conventional case.

  Next, a case of reporting a PA or the like will be described with reference to FIGS. In FIG. 3, a one-dot chain line 209 indicates the flow of the PA signal, and a dotted line 210 indicates the flow of the PA transmission command. Although not shown, the power signal always passes through the LPF 205 as in FIG. FIG. 4 is a flowchart showing the operation of the content distribution system in the case of PA notification. In FIG. 4, when a situation requiring PA notification occurs, the switch control unit 104 of the server apparatus 100 first selects multicast communication by the switch 103 (step S1). Prior to sending the PA notification, the multicast server 102 first sends a PA command to all SEBs (step S2). The control unit 204 of the SEB 108 that has received the PA command instructs the built-in LPF 205 to turn off the filter function, and the LPF 205 turns off the filter function based on this instruction (step S3). Next, the multicast server 102 transmits a PA notification to all SEBs by multicast communication (step S4). This PA notification flows along a route indicated by a one-dot chain line 209 in FIG. 3 and reaches the passenger terminal 111 via the PLC adapter 201 and the control unit 204 to the SEB 108. At the same time, the PA notification passes through the LPF 205 and is transmitted to the next-stage SEB 109 (not shown). In this way, the PA notification is sequentially transferred to the SEB and reaches the last SEB 110. In this way, the PA notification is transmitted to all SEBs and reaches all passenger terminals at approximately the same time. Finally, when the PA notification is finished (step S5), the control unit 204 issues an instruction to the LPF 205 to turn on the filter function (step S6), and all transmissions are finished.

  As described above, according to the present embodiment, the LPF is incorporated in the SEB and each SEB is separated in a network, and at the same time, the content data transmitted from the server device 100 is sequentially transmitted via the memory 203. Transfer to the next stage. As a result, even when content data is downloaded to all SEBs in advance by unicast communication, it can be transmitted at high speed and stably. Further, by turning off the function of the LPF 205 at the time of multicast communication, it becomes possible to transmit the PA notification to all passenger terminals without delay.

  In the above-described embodiment, an example of application to IFE in an aircraft has been described as an example of a content distribution system provided in a transportation facility. It may be a transportation.

  In the above-described embodiment, the PA server is transmitted from the multicast server 102 and the LPF is turned off. However, when the PA notification time is known in advance, it is automatically detected when the PA notification time is reached. Alternatively, the LPF may be turned off.

  The present invention is widely applicable to a data transmission apparatus, a content distribution system, and the like that transmit data using power line communication.

1 is a block diagram showing a configuration of a content distribution system according to Embodiment 1 of the present invention. The block structure which shows the structure inside SEB, and the figure which shows the signal flow at the time of unicast communication The block structure which shows the structure inside SEB, and the figure which shows the signal flow at the time of unicast communication Flow chart showing operation of content distribution system in case of PA notification

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Server apparatus 101 Unicast server 102 Multicast server 103 Switch 104 Switch control part 105,201,202 PLC adapter 106 Power supply 107 Power line 108,109,110 SEB (data transmission apparatus)
111, 112, 113 Passenger terminal 203 Memory 204 Control unit 205 LPF

Claims (7)

A data transmission device for transmitting data with frequency superimposed on a power line,
A memory for storing the data;
A control unit for controlling writing and reading of the memory;
A first power line adapter and a second power line adapter that superimpose or separate the data on the power line; and
A filter that is sandwiched and connected between the first power line adapter and the second power line adapter, passes the commercial power frequency, and blocks the superimposed frequency of the data;
A controller that writes data extracted from the first power line adapter to the memory, reads the written data, and superimposes the data on the power line by the second power line adapter;
A data transmission device comprising: The control unit determines whether the data is transmitted by unicast communication or multicast communication, and a function of controlling whether to insert the filter based on a determination result of the determination unit The data transmission device according to claim 1, further comprising: A plurality of data transmission devices according to claim 1 connected to a distribution server in cascade via a power line, and video and audio stored in the distribution server in response to a request from a passenger terminal connected to the data transmission device And a content distribution system for providing at least one piece of data to the passenger terminal,
Prior to a request from the passenger terminal, the distribution server sequentially transmits the data to all the data transmission devices by unicast communication, and the data transmission device stores the data in the memory. Content distribution system. 4. The content distribution system according to claim 3, wherein the data transmission device transfers the data to the next data transmission device before the data is completely stored in the memory. 5. A plurality of data transmission devices according to claim 2 are cascade-connected to a distribution server via a power line, and video and audio stored in the distribution server in response to a request from a passenger terminal connected to the data transmission device And a content distribution system for providing at least one piece of data to the passenger terminal,
The distribution server distributes the data to the data transmission device by unicast communication or multicast communication,
The content distribution system, wherein the filter of the data transmission device is inserted when the data is distributed by unicast communication, and the filter is not inserted when the data is distributed by multicast communication. The content distribution system according to claim 5, wherein the distribution server transmits PA information to the data transmission apparatus by multicast communication. The content distribution system according to any one of claims 3 to 6, wherein when an error occurs in the unicast communication, retransmission is performed in a MAC layer of power line communication.

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