KR20090008472A - Method and device for wireless transmission of internet protocol TV - Google Patents

Abstract

The invention relates to a method for transmitting a television data stream via a wireless network connection. The method comprises receiving at least one television data stream via the User Datagram Protocol (UDP); converting said at least one UDP television data stream into a Transmission Control Protocol (TCP) data stream; and transmitting said TCP data stream via said wireless network connection over a point-to-point link.

Description

Method and device for wireless transmission of Internet Protocol TVs {Method and device for wireless transmission of Internet Protocol TV}

The present invention relates to Internet protocol television (IPTV), and in particular to methods and devices for transmitting IPTV over wireless networks.

Transmission of TV and video on demand signals over the Internet is becoming more and more common. Many commercial services already exist. Internet Protocol Television (IPTV) refers to a system in which digital television services are delivered to subscribing consumers using the Internet Protocol over a broadband connection (eg, a widely used xDSL connection). This service is often provided in association with Video on Demand and is typically provided by a broadband operator using the same infrastructure.

IPTV covers live video (multicasting) as well as stored video content (Video on Demand). Playback of IPTV requires a set-top box or personal computer device connected to the TV. Video content is typically delivered via IP Multicast. It is a way in which information can be sent to multiple computers at the same time. In standards-based IPTV systems, the main underlying protocols used for IPTV are channel change signaling for live TV and Real Time Streaming Protocol (RTSP) for video on demand. Version 2 of the Internet Group Management Protocol (IGMP).

Wireless Local Area Networks (WLAN), Worldwide Interoperability for Microwave Access (WiMAX), and other wireless technologies are used to provide wireless Internet access in homes, offices, and certain hot-spots . In general, UDP based multicast / broadcast streaming protocols are used with video signals because they operate more efficiently compared to the TCP protocol. Multicasting is also not possible with TCP, because re-transmission state machines must be link specific. That is, they cannot be shared by so many receivers as required in video streaming applications. However, the UDP protocol inherits certain quality issues in wireless connections.

User Datagram Protocol (UDP) is one of the core protocols of the Internet Protocol Suite. UDP is defined to enable the datagram mode of packet-switched computer communication in the environment of a set of interconnected computer networks. This protocol requires that the Internet Protocol (IP) be used as the underlying protocol. Using UDP, programs on networked computers can send each other short messages known as datagrams. UDP does not provide the reliability and ordering that TCP guarantees. That is, datagrams may arrive out of order or even be lost without notice. In other words, packets are likely to be lost or corrupted during transmission. However, since UDP has a reduced overhead compared to TCP, as a result UDP is faster and more efficient for many light weight or time-sensitive purposes. Thus, and because of the possibility of multicasting by UDP unlike in the case of TCP, UDP is used in applications as IPTV.

In the UDP protocol, packets are sent from the transmitter to the receiver without feedback on transmission success (ie, no acknowledgment scheme). Although the receiver cannot extract the correct information from the received packet, there is no means provided to request retransmission of the packet. Based on the degree of loss, the client can restore the data with error correction techniques, interpolate the lost data, or process it as a dropout. Small amounts of dropouts are tolerable compared to the time delays due to data packets being retransmitted in some applications such as Voice over IP (VoIP).

Typically these characteristics of UDP in a wired Ethernet network are not a problem. This is because the transmission medium is reliable and relatively insensitive to disturbances. The situation is different in unmanaged radio connections such as WLAN. The environment is not favorable and the quality of the wireless links can change for a number of different reasons. In addition, the actual throughput is lower than the theoretical peak bit rate due to the low layer overhead (especially the preamble needed for L1 synchronization). For these reasons, WLAN and other wireless technologies have serious quality issues in providing high quality video and IPTV services using the UDP protocol.

Typically, the Internet infrastructure is implemented such that WLANs and other wireless access technologies are only used to cover the last distance of the last tens of yards within a home, office, or specific point of view. In practice, connections to wireless access points are typically made by xDSL, optical or other wire-based techniques. In conventional situations, IPTV terminals are connected to xDSL modems via wire-based Ethernet connections. It would be beneficial to be able to replace such wired connections with WLAN or similar wireless connections. These are already widely used in small home or office networks that connect PCs, laptop computers and even PDAs with the Internet at home or in the office.

However, the above-mentioned problems related to IPTV arise from the scenario in which a WLAN connection is used in the Internet connection for IPTV. In contrast to cable connections, wireless connections have signal attenuation, interference generated by other devices using the same un-controlled radio band, and, for example, portable IPTV. Multi-path propagation or channel variation when the user carrying the playback device is mobile is prone to errors and less reliable. However, the UDP protocol used in IPTV expects a reliable connection and therefore does not provide acknowledgment of received packets. As a result, packet retransmission is not provided. The conventional solution adds redundancy to the transmitted signal to recover disturbs. This is done in the form of forward error correction and by interleaving TV data on multiple IP packets. However, this reduces the processing capacity of the system. Since the original MPEG-2 stream already requires most of the 8 MBit / s ADSL link, for example, there is very little reserve capacity for such error correction schemes.

It would be beneficial if the IPTV terminals could be connected using a wireless technology such as WLAN without being subjected to data corruption likely in video transmission based on the combination of WLAN and UDP. This may also allow wireless access connections to be used for UDP based TV and video broadcast streams. This helps to reduce the expensive cabling that may otherwise be needed in homes and offices. Therefore, an object of the present invention is a method and device for reliably relaying UDP-based (also possibly multicast) IPTV on wireless IP networks using point-to-point links. To provide them. The invention also enables the use of existing IPTV playback hardware / software and is interoperable with existing IPTV providers using broadband Internet connections.

According to one aspect of the present invention there is provided a method for transmitting a television data stream via a wireless network connection. The method includes receiving at least one television data stream via a User Datagram Protocol (UDP); Converting the at least one UDP television data stream into a Transmission Control Protocol (TCP) data stream; And transmitting the TCP data stream over the wireless network connection on a point-to-point link.

The method according to the invention makes it possible to transmit UDP based television data streams in a reliable manner over a wireless network. Therefore, high video quality without artifacts is ensured. The method can be applied to conventional UDP based IPTV streams, thus maintaining the interoperability with existing providers as well.

In one exemplary embodiment, the UDP television data stream is a multicast data stream.

In one exemplary embodiment, a plurality of UDP data streams are received, the method further comprising selecting the at least one UDP television data stream from the plurality of UDP data streams.

If a general internet connection is used to receive the IPTV stream, other UDP data streams that are not related to the television may also be received. This embodiment therefore provides a means for selecting at least one UDP television data stream to be transmitted. Using this embodiment, it is also possible to select among a number of incoming UDP television data streams.

In one exemplary embodiment, the method further comprises receiving a request for at least one particular television data stream on the wireless network connection, wherein selecting the at least one UDP television data stream comprises: Runs on request

This embodiment makes it possible, for example, to select a particular television data stream from a plurality of television programs. It also offers the possibility of a characteristic that the transmitting end decides which one to select from among a plurality of UDP streams (both television data streams and other UDP data streams) for transmission.

Selecting a multicast stream may be based on a peer-to-peer link. For example, opening a TCP connection to a particular TCP port selects a particular UDP (multicast) port on the server or changes the server. Electronic Program Guide (EPG) information (eg, program ID, etc.) included in the request may also be used to select the actual UDP stream.

According to another aspect of the invention there is provided a method for receiving a television data stream via a wireless network connection. The method includes receiving a TCP data stream carrying at least one UDP television data stream via a wireless network connection; Extracting at least one UDP television data stream from the TCP data stream; And outputting the at least one UDP television data stream.

The method according to the invention makes it possible to receive UDP-based television data streams carried in a TCP data stream over a wireless network in a reliable manner. Therefore, high video quality without artifacts is ensured. Since this method can also be used to generate a conventional UDP television data stream as output, it can be used in connection with conventional UDP based IPTV playback devices and thus with existing playback devices and / or software. Interoperability with existing playback devices and / or software is also maintained.

In one exemplary embodiment, the method further comprises transmitting a request for at least one particular television data stream via the wireless network connection.

This request may, for example, comprise opening a TCP connection to a particular TCP port to select a particular UDP (multicast) port on the server or to change the server. Electronic Program Guide (EPG) information (eg, program ID, etc.) may also be included in the request to select the actual UDP stream. This embodiment allows the receiving end to request a particular television data stream, eg, from multiple television programs. It also offers the possibility to provide certain characteristics to the transmitting end. The characteristic relates to the transmission end deciding which one to select from among a plurality of UDP streams (both television data streams and other UDP data streams) for transmission.

According to another aspect of the present invention, a computer program product is provided. The computer program product is stored on a computer-readable medium and has program code means for instructing a computer to execute the method described above.

According to another aspect of the invention there is provided a transmission device for transmitting a television data stream via a wireless network connection. The transmitting device comprises an interface adapted to receive at least one television data stream via a User Datagram Protocol (UDP); A converter adapted to convert the at least one UDP television data stream into a Transmission Control Protocol (TCP) data stream; And a wireless transceiver adapted to transmit the TCP television data stream over the wireless network connection on a point-to-point link.

In one exemplary embodiment, the adapted interface is adapted to receive a multicast UDP television data stream.

The interface may be implemented with, for example, a Digital Subscriber Line (xDSL) interface, a cable, Ethernet, optical or other broadband network interface capable of reliably providing UDP television data streams. have. The wireless transceiver may be provided for operation in accordance with any wireless standard (eg, WLAN) with sufficient available bandwidth for transmitting TCP data streams.

In one exemplary embodiment, the transmission device further comprises a buffer connected between the interface and the converter. The buffer is adapted to buffer the at least one UDP television data stream.

In one exemplary embodiment, the interface is adapted to receive a plurality of UDP data streams. The device further comprises a selector adapted to select at least one UDP television data stream from the plurality of UDP data streams for the conversion.

In one exemplary embodiment, the wireless transceiver is adapted to receive a request for at least one particular television data stream. The selector is adapted to carry out selecting the at least one UDP television data stream in accordance with the request.

In one exemplary embodiment, the wireless transceiver is a wireless local area network (WLAN) transceiver.

According to a further aspect of the invention

A receiver device for receiving a television data stream via a wireless network connection is provided. The receiver device comprises: a wireless transceiver adapted to receive a TCP data stream carrying at least one television data stream; An extractor adapted to extract the at least one television data stream from the TCP data stream; And an output interface for outputting the at least one television data stream.

In one exemplary embodiment, the wireless transceiver is adapted to send a request for at least one particular television data stream.

In one exemplary embodiment, the wireless transceiver is a WLAN transceiver.

In one exemplary embodiment, the device further comprises a playback component connected to the output interface. The playback component is adapted to play the television data stream and has at least a display and a loudspeaker.

The accompanying drawings are provided for illustratively describing preferred embodiments of the present invention. They are illustrative only and are not intended to limit the scope of the invention to the specific embodiments described herein.

1 shows a flow diagram of one embodiment according to the method of the present invention on a transmitting end.

Figure 2 shows a flow diagram of one embodiment according to the method of the present invention on the receiving end.

3a and 3b show embodiments of a transmission device according to the invention.

4a and 4b show embodiments of a receiver device according to the invention.

1 is a flow diagram illustrating one embodiment according to the method of the present invention, implemented on a transmitting end.

In a first step 102, a plurality of UDP data streams are received. These UDP data streams may contain various actual content, Domain Name Service requests and answers, Voice over IP telephony data, and one or more multicast UDP television data. IP television data, which may include streams, possibly even more than one TV broadcast. In these general cases where more than one UDP data stream arrives at a transmission end (eg, a wireless router), it is necessary in the method of the invention to select at least one UDP television data stream.

Therefore, in step 104, a request for a particular television data stream is received. In advanced embodiments this may include a request for more than one television data stream. This request allows the user to select a particular TV program or multiple TV programs to be sent. According to the request, at least one UDP television data stream is selected in step 106. If the request indicates more than one television data stream, the corresponding number of UDP television data streams is selected according to the request.

In step 108 at least one selected UDP television data stream is optionally buffered. In another embodiment, buffering may optionally be performed after step 110, ie on the TCP side.

The switch to TCP protocol according to the invention is carried out in step 110. The resulting TCP data stream is then transmitted over a wireless network connection (eg, WLAN) in step 112 and received by the receiver device in accordance with the present invention.

It should also be noted that at step 102 only one UDP television data stream may be received. In this case, step 104 is omitted. However, there may also be situations where only step 104 is optional. That is, a situation where multiple UDP data streams are received but at least one UDP television data stream is selected by other means. For example, in some embodiments of the present invention, it is also possible to simply select all television type UDP data streams while omitting DNS related traffic and other non-TV data streams. In addition, step 108 may also be optional only, since buffering is not always necessary or beneficial.

2 is a flow diagram illustrating one embodiment according to the method of the present invention, implemented on a receiving end. In a first step 202, a request for a particular television data stream is sent, for example to select a particular TV broadcast. This step is optional, and the request can also direct more than one TV broadcast / program.

In response to the request a TCP data stream will be received at step 204. According to the present invention, the requested TV data stream, which is a UDP television data stream, is converted to the TCP protocol. In addition to receiving a TCP data stream in step 204, sending a request in step 202 is performed over a wireless network connection (eg, a WLAN).

In step 206, the television data stream is extracted or recovered from the received TCP data stream. That is, the television data stream now exists in its original form, which has arrived at the transmission end (see FIG. 1) with respect to the data payload. The television data stream is then output at step 208 and reproduced, for example, by a portable WLAN network device with a display screen and loudspeakers or ear phones. The extraction and / or its output can optionally be performed via back-conversion to the UDP protocol, ie by restoring the original UDP television data stream.

Although the new transmission scheme according to the present invention is not compatible with itself, it is an important advantage of the present invention that standard IPTV hardware and / or software can be used to actually play the IPTV stream. For example, a WLAN-based PDA or similar device that already has playback software for playing UDP-based IPTV only needs to be refitted to support the transmission scheme of the present invention, and the playback software does not change. Can remain. In other words, the present invention can provide transparent transmission of (multicast) UDP based IPTV.

In figure 3a the transmission device according to the invention is shown in a three-dimensional view. For example, the device may be implemented as a wireless router or access point 2. The wireless router 2 has a wireless network interface 4 shown as an antenna and a fixed broadband Internet access interface 6 connected to a general Internet access terminal 8. The terminal 8 may be an xDSL connection, a cable connection or another broadband Internet connection. The invention is not limited to an internet connection and may be used in any other network capable of reliably providing UDP television data streams, such as a conventional Ethernet cable network.

FIG. 3B illustrates internal components of the device shown in FIG. 3A. As shown in FIG. 3A, the interface 6 is provided for connection with the Internet, or other similar network. It is connected to a converter 10 adapted to convert the UDP television data stream arriving via the interface 6 into a TCP data stream. The converter 10 is connected to an air interface 4 adapted to transmit a TCP data stream over the air network. Optionally, a buffer 12 may be provided between the converter 10 and the interface 6 for buffering, prior to conversion, UDP television data streams flowing through the interface 6. In another embodiment (not shown), an optional buffer may be provided on the TCP side, i.e., to buffer the converted TCP data stream.

In figure 4a a receiver device according to the invention is shown in a three-dimensional view. Shown here is a portable WLAN TV terminal device 20. However, the present invention is not limited thereto and may be used in connection with any portable or fixed IPTV device (eg, mobile phone, PDA, set top box device or laptop computer) having a wireless network interface. The terminal device 20 has a display screen 24 and two loudspeakers 26. It also has a wireless interface 22 pointed to by an antenna.

4B shows internal components of the device shown in FIG. 4A. Receiver device 20 has a wireless network interface 22 (eg, a WLAN transceiver). An extractor 28 is connected thereto to receive the incoming TCP data stream over the air interface 22. Extractor 28 is adapted to extract the television data stream carried within the TCP data stream in accordance with the present invention. The receiver device 20 further comprises an output interface 30 connected to the extractor for receiving the extracted television data stream. The output interface 30 may be, for example, an internal interface connected to the display screen 24 and the loudspeakers 26 as shown in FIG. 4A. In another embodiment it may be an external interface connected to a playback device, such as a standard TV set with S-VIDEO and audio cinch connectors, SCART and the like. In this case the receiver device is only a reception module for delivering the wirelessly received television data stream to the playback device, for example via an HDMI or DVI interface. For analog playback devices as conventional television sets, suitable AV decoders and digital / analog converters can be provided.

It should be noted that in the example embodiments described above, certain components (eg, power supply) have been omitted to improve clarity. Since such are known per se and are not important for the understanding of the present invention, they will not be described in detail. For example, a suitable power supply may be a typical Li Ion accumulator in a PDA or other portable IPTV playback device or a wall plug transformer in a wireless router or access point.

According to the present invention, relaying of (multicast) UDP-based IPTV traffic is performed by converting the UDP protocol used in IPTV distribution to a TCP-based protocol for the radio link. This is feasible if the wireless connection has sufficient capacity for the TCP protocol. This is typically the case in home environments. This is because radio connection transmission rates are usually higher than typical xDSL transmission capacities [256 kbit / s to 8 Mbit / s and above]. [Wireless WLAN standards as 802.11 A, B, G are 11 Mbit / s, Maximum bandwidths of 54 Mbit / s and 108 Mbit / s.

According to the present invention, the switch from UDP to TCP protocol can be performed in a wireless router, a wireless access point or a multimedia PC. To be able to handle this transition, the router must know which UDP streams should be converted to TCP streams. For that reason, certain features must be built into routers or wireless access points.

In general, an IPTV viewing terminal sends a signal to an IPTV server and multicast routers on the path for the TV-channels or programs of interest, which IPTV server then uses an UDP stream for the IPTV terminal. Starts multicasting the desired program. IGMP is typically used to open a multicast stream to be placed on a local connection.

In the present invention, the wireless router receives an IPTV stream from an IPTV server. It then forwards the UDP stream to connections (eg fixed connections) that can (optionally) handle UDP streams reliably. In wireless connections, the wireless router buffers the UDP stream, converts it into a TCP-based data stream, and relays the stream on wireless connections (eg, WLAN). Since the transmission capacity of the wireless link is higher than the xDSL connection, the TCP protocol can handle the retransmissions needed in case of errors on the wireless connection. It guarantees high video end quality.

The IPTV terminal, ie receiver device, according to the invention can each handle TCP-based TV data streams and can receive the actual TCP TV stream from a wireless router or transmission device. The receiver device may instruct the router that a TCP stream is needed instead of a UDP stream. This may include requesting which of the plurality of incoming UDP data streams from the router should be selected or picked up for IPTV transmission according to the present invention. Since an Internet connection will usually be shared between IPTV and normal Internet traffic, this may be necessary in situations where there are multiple UDP streams and some of which are not television data streams.

Claims (17)

A method for transmitting television data streams over a wireless network connection, the method comprising: Receiving at least one television data stream via a User Datagram Protocol (UDP); Converting the at least one UDP television data stream into a Transmission Control Protocol (TCP) data stream; And Transmitting the TCP data stream over the wireless network connection on a point-to-point link; Method of providing. The method of claim 1, And said UDP television data stream is a multicast data stream. The method according to claim 1 or 2, Multiple UDP data streams are received, Selecting the at least one UDP television data stream from the plurality of UDP data streams; The method further comprising. The method of claim 3, wherein Receiving a request for at least one particular television data stream on the wireless network connection; Selecting the at least one UDP television data stream is performed according to the request. A method for receiving a television data stream via a wireless network connection, the method comprising: Receiving, over a wireless network connection, a TCP data stream carrying at least one television data stream; Extracting at least one television data stream from the TCP data stream; And Outputting the at least one television data stream; Method of providing. The method of claim 5, wherein Sending a request for at least one particular television data stream via the wireless network connection; The method further comprising. In a computer program product, A computer program product stored on a computer-readable medium, comprising program code means for instructing a computer to execute a method according to any one of claims 1 to 6. A transmission device for transmitting a television data stream via a wireless network connection, comprising: An interface adapted to receive at least one television data stream via a User Datagram Protocol (UDP); A converter adapted to convert the at least one UDP television data stream into a Transmission Control Protocol (TCP) data stream; And A wireless transceiver adapted to transmit the TCP television data stream over the wireless network connection on a point-to-point link; Device comprising a. The method of claim 8, And the adapted interface is adapted to receive a multicast UDP television data stream. The method according to claim 8 or 9, Wherein the interface is a digital subscriber line (xDSL) interface. The method according to any one of claims 8 to 10, The interface is adapted to receive a plurality of UDP data streams, The device, A selector adapted to select at least one UDP television data stream from the plurality of UDP data streams for the conversion; The device further comprising. The method according to any one of claims 8 to 11, The wireless transceiver is adapted to receive a request for at least one particular television data stream, And the selector is adapted to execute selecting the at least one UDP television data stream in accordance with the request. The method according to any one of claims 8 to 12, And wherein the wireless transceiver is a wireless local area network (WLAN) transceiver. A receiver device for receiving a television data stream via a wireless network connection, the receiver device comprising: A wireless transceiver adapted to receive a TCP data stream carrying at least one television data stream; An extractor adapted to extract the at least one television data stream from the TCP data stream; An output interface for outputting the at least one television data stream; Device comprising a. The method of claim 14, The wireless transceiver is adapted to transmit a request for at least one particular television data stream. The method according to claim 14 or 15, And wherein said wireless transceiver is a WLAN transceiver. The method according to any one of claims 14 to 16, A playback component connected to the output interface; The playback component is adapted to play the television data stream, and has at least a display and a loudspeaker.

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