The invention relates generally to the communication of streaming data to a mobile platform and more particularly to correcting data loss errors that occur during wireless transmission of Internet Protocol (IP) multicast data streams.
The transmission of reliable multicast data over wireless channels is typically unreliable due to data losses during the transmission. Conversely, unicast wireless transmissions, e.g. TCP transactions, for such things as ‘surfing’ the Internet and e-mail transmissions are generally more reliable because unicast transmissions are acknowledged transmissions. That is, when a packet of data is sent, via unicast transmissions, an acknowledgement is returned indicated whether or not the data packet was received. Thus, if a data packet is not received, the acknowledgement indicates so and the data packet is resent to correct the error. However, multicast data transmissions do not include an acknowledgement and have no embedded correction mechanism. Thus, if any bit errors occur in a packet, the entire packet can be corrupted and lost, the sender will be unaware of the lost data, and the target receives streaming data that is missing data. For example, packets in a multicast audio or video stream, are quite large, e.g. 1500 bytes, thus, losing one packet can result in ‘choppy’ streaming, ‘freeze frames’ or gaps in the audio or video.
The occurrence of data loss can be amplified when the wireless multicast streaming data is transmitted within a closed environment such as a mobile platform, e.g. an aircraft, train, bus or ship. The characteristics of wireless multicast transmissions within a mobile platform are such that the electromagnetic waves can propagate through the interior of the mobile platform and cause destructive interference with each other. Even further losses can occur within a closed environment due to hardware characteristic of the devices receiving the multicast signals, e.g. laptop computers. The wireless cards or antennas of the receiving devices can be very inefficient and cause considerable packet loss. Additionally, typically the error correction software accompanying such devices provide only a low level, inefficient correction scheme.
Therefore, it would be desirable to wirelessly multicast streaming data, e.g. live news, sports, etc., within a closed environment, such as a mobile platform, efficiently and with error correction to correct for data loss.
In a preferred embodiment of the present invention, a method for multicasting Internet Protocol (IP) streaming data to a mobile platform passenger is provided. The method includes receiving data content at a base station network from a content provider. The received data is formatted at the base station into an IP multicast data stream and communicated to a mobile platform communications system onboard a mobile platform. The mobile platform communications system includes a local area network (LAN) used to distribute the IP multicast data stream to at least one mobile platform client interface, e.g. a laptop computer. The data content of the IP multicast data stream is then displayed on the mobile platform client interface for viewing by a mobile platform passenger or crew member. Additionally, the method includes applying forward error correction (FEC) to the IP multicast data stream to correct for data losses, prior to distributing the IP multicast data stream to the mobile platform client interface. The method further includes decoding the FEC encoded IP multicast data stream so that the corrected data content can be interpreted and displayed on the mobile platform client interface.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. Furthermore, the features, functions, and advantages of the present invention can be achieved independently in various embodiments of the present inventions or may be combined in yet other embodiments.
The present invention will become more fully understood from the detailed description and accompanying drawings, wherein;
Corresponding reference numerals indicate corresponding parts throughout the several views of drawings.
Generally, the base station 14 receives streaming data from a content provider that can be any multimedia source adapted to provide information and/or entertainment data. For example, the content provider can be any multimedia source that provides such things as news, sports, music, movies, stock market information, Internet access and other types of information or entertainment data. The base station 14 formats the data from the content provider into an internet protocol (IP) multicast data stream that is communicated to the satellite gateway 18.
A multicast data stream is a non-acknowledgement transaction, as opposed to a unicast data stream which sends an acknowledgement back indicating whether an end user device received all the data intact. Thus, if data bits or data packets are not received by the end user device, the device will not know there is missing or lost data and improperly or incompletely interpret and/or display the data content. Generally, multicast is more efficient than unicast in distributing the same data to multiple recipients. Unicast send data as many times as there are recipients, whereas multicast will distribute the data to all recipients in a single transmission. Wireless communications such as communications to a mobile platform is typically restricted to low bandwidth, for example 5 to 10 megabits that would only support a few, e.g. six or seven, end user devices using unicast scheme. Thus, communications to and/or within mobile platforms generally incorporate multicast to efficiently transmit data to multiple recipients.
The IP multicast data stream can be communicated between the base station 14 and the satellite gateway 18 using any suitable wired or wireless communication means. The IP multicast data stream is communicated from the satellite gateway 18 to the satellite 22 and then to the onboard communications system 26, particularly to an antenna 34 included in the onboard communications system 26. The antenna 34 is communicatively connected to a receive/distribute subsystem 38 of the onboard communications system 26.
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In one implementation of this embodiment, the FEC processing component 70 encodes the IP multicast data stream and communicates the FEC encoded IP multicast data stream to the mobile platform server 46A, which in turn, communicates the FEC encoded IP multicast data stream to the client interface 50, via either wired or wireless connections. The client interface 50 includes IP and FEC decoding software adapted to decode the IP format and the FEC of the FEC encoded IP multicast data stream so that the decoded data content can be displayed and viewed by either a passenger or crew member.
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The FEC encoder 74 then communicates the FEC encoded IP multicast data stream to the communications transmission component 62 that, in turn communicates the FEC encoded IP multicast data stream to the satellite gateway 18 and subsequently to the mobile platform communications receiving component 42, via the satellite 22 and the mobile platform antenna 34.
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In another implementation of this embodiment, the FEC processing component 70 decodes the FEC of the FEC encoded IP multicast data stream and communicates the IP multicast data stream to the mobile platform server 46A, which in turn, communicates the IP multicast data stream to the client interface 50, via either wired or wireless connections. The client interface 50 includes IP decoding software adapted to decode the IP of the IP multicast data stream so that the decoded data content can be displayed and viewed by either a passenger or crew member.
In yet another implementation of this embodiment, the FEC processing component 70 decodes the FEC, then re-encodes the IP multicast data stream with FEC and communicates the FEC re-encoded IP multicast data stream, via wired or wireless connections, to the mobile platform server 46A. The mobile platform server 46A communicates the FEC re-encoded IP multicast data stream to the client interface 50, via either wired or wireless connections. The client interface 50 includes IP and FEC decoding software adapted to decode the IP format and the FEC of the FEC re-encoded IP multicast data stream so that the decoded data content can be displayed and viewed by either a passenger or crew member.
In still yet another implementation of this embodiment, the FEC processing component 70 adds a second layer of FEC to the existing FEC encoded IP multicast stream, creating a cumulative FEC protected stream. The FEC processing component 70 then communicates the cumulative FEC encoded IP multicast data stream, via wired or wireless connections, to the mobile platform server 46A. The mobile platform server 46A communicates the FEC re-encoded IP multicast data stream to the client interface 50, via either wired or wireless connections. The client interface 50 includes IP and FEC decoding software adapted to decode the IP format and the FEC of the cumulative FEC encoded IP multicast data stream so that the decoded data content can be displayed and viewed by either a passenger or crew member.
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In another implementation of the this embodiment, the FEC processing component 70, decodes the FEC, then re-encodes the IP multicast data stream with FEC and communicates a FEC re-encoded IP multicast data stream, via wired or wireless connections, to the mobile platform hub 46B. The mobile platform hub 46B communicates the FEC re-encoded IP multicast data stream, via either wired or wireless connections, to the client interface 50 that includes IP and FEC decoding software. Thus, the client interface 50 decodes the IP format and the FEC of the FEC re-encoded IP multicast data stream and displays the decoded data content to be viewed by either a passenger or crew member.
In yet another implementation of this embodiment, the FEC processing component 70 adds a second layer of FEC to the existing FEC encoded IP multicast stream, creating a cumulative FEC protected stream. The FEC processing component 70 then communicates the cumulative FEC encoded IP multicast data stream, via wired or wireless connections, to the mobile platform hub 46B. The mobile platform hub 46B communicates the FEC re-encoded IP multicast data stream to the client interface 50, via either wired or wireless connections. The client interface 50 includes IP and FEC decoding software adapted to decode the IP format and the FEC of the cumulative FEC encoded IP multicast data stream so that the decoded data content can be displayed and viewed by either a passenger or crew member.
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In another implementation of the this embodiment, the FEC processing component 70, decodes the FEC, then re-encodes the IP multicast data stream with FEC and communicates a FEC re-encoded IP multicast data stream, via wired or wireless connections, to the mobile platform WLAN 46C. The mobile platform WLAN 46C wirelessly communicates the FEC re-encoded IP multicast data stream to the client interface 50 that includes IP and FEC decoding software. Thus, the client interface 50 decodes the IP format and the FEC of the FEC re-encoded IP multicast data stream and displays the decoded data content to be viewed by either a passenger or crew member.
In yet another implementation of this embodiment, the FEC processing component 70 adds a second layer of FEC to the existing FEC encoded IP multicast stream, creating a cumulative FEC protected stream. The FEC processing component 70 then communicates the cumulative FEC encoded IP multicast data stream, via wired or wireless connections, to the mobile platform WLAN 46C. The mobile platform WLAN 46C wirelessly communicates the FEC re-encoded IP multicast data stream to the client interface 50 that includes IP and FEC decoding software adapted to decode the IP format and the FEC of the cumulative FEC encoded IP multicast data stream so that the decoded data content can be displayed and viewed by either a passenger or crew member.
If the mobile platform communications system 26 receives an IP multicast data stream that has not been encoded with FEC, the IP multicast data stream is encoded with FEC utilizing the FEC processing component 70, as indicated at 122. Alternatively, if the mobile platform communications system 26 receives an FEC encoded IP multicast data stream and the FEC encoded IP multicast data stream is FEC decoded at 112, the decoded IP multicast data stream can be re-encoded with FEC utilizing the FEC processing component 70, as also indicated at 122. If the FEC encoded IP multicast data stream is not FEC decoded at 112, the FEC processing component 70 can apply further FEC encoding to the FEC encoded IP multicast data stream to create a cumulative FEC encoded IP multicast data stream. The FEC encoded, cumulative encoded, or re-encoded IP multicast data stream is distributed to the client interface 50, where the client interface decodes the FEC encoded IP multicast data stream and displays the data content, in accordance with the various embodiments described above, as indicated at 124 and 126.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.