WO2002031670A1

WO2002031670A1 - Method of and system for delivering receiver-selectable quality of service over networks

Info

Publication number: WO2002031670A1
Application number: PCT/US2001/031861
Authority: WO
Inventors: Gilbert Irving Cardwell
Original assignee: Teraglobal Communications Corp.
Priority date: 2000-10-12
Filing date: 2001-10-12
Publication date: 2002-04-18
Also published as: WO2002031670A8

Abstract

A method and system (11) for transmitting data (21) at receiver-selectable image and motion quality. The data (21) is decomposed into frames, and the frames may be decomposed into bands, with each of the bands adding data to the preceding band. The frames and/or bands are transmitted individually or in groups at different rates on different channels. Each receiver (15) can subscribe to the channels that provide a desired level of image and motion quality for the bandwidth available to each receiver (15).

Description

METHOD OF AND SYSTEM FOR DELIVERING RECEIVER-SELECTABLE QUALITY OF SERVICE OVER NETWORKS

BACKGROUND OF THE INVENTION

The present invention relates generally to data communication. More particularly, the invention relates to providing receiver-selectable video and audio quality of service over networks.

The presentation of audio and video data has become an important application of personal computers and similar devices. The processing power of personal computers continues to double about every two years and computer display technology has advanced in resolution and color capability. Digital compression technology continues to advance so that high quality video and audio data can be transmitted at lower bit rates. At the same time, network transport technology has advanced to create extremely high bandwidth network backbones. All of these factors have combined to make personal computers an ideal platform on which to implement the features of digital video and audio.

The power of personal computers and network technology make possible the transmission of audio and video data in real time. Such real time transmission is useful in conferencing applications in which multiple participants can have access to the information. However, real time video conferencing is not without problems.

One of the problems associated with real time video conferencing lies in the fact that all participants may not have high-bandwidth connections to the network backbone. Current optical-network transport technology provides bandwidths in excess of 10 gigabits per second (Gbps). While some receivers may have access to technology such as high-speed asymmetric digital subscriber lines (ADSL) or fast Ethernet connections that provide bandwidths in excess of 100 megabits per second (Mbps), other receivers may have access to technology such as token ring local area networks (LANs), thin Ethernet connections, or cable modem technology, which provide bandwidths in the range of 10 Mbps to 20 Mbps. Still other receivers may have access to the network backbones through Tl lines, which provide a bandwidth of 1.544 Mbps, or integrated-services digital-network (ISDN) lines, which provide a bandwidth of 128 kilobits per second (Kbps).

A video signal is essentially a continuous stream of still picture images, called frames. Each picture image comprises a set of pixels. Each pixel is defined by a binary number. For example, 24-bit per pixel (bpp) pixels use 8 bits for each of the colors red, green, and blue. The transmission of a 640x480 pixel video window at 30 frames per second requires a data rate of 27.6 Mbps, i.e., an ADSL line or a fast Ethernet connection. Because of the redundancy from pixel to pixel within a frame and the motion redundancy from frame to frame, substantial data rate savings can be accomplished by compression. However, even with compression, the data rate for large- window, full-motion video exceeds the bandwidth available to many receivers. Also, certain motion compression and decompression standards, such as Moving Pictures Experts Group (MPEG), require substantial computer processing, which can make real-time viewing difficult.

There are several strategies currently available for reducing the bandwidth required for transmitting video data. One strategy is to transmit fewer pixels by reducing the size of the window in which the video image is displayed. The data rate required to transmit an image is proportional to the area of the image. Thus, the window size may be reduced until the data rate becomes manageable. However, in order to meet existing bandwidth constraints, the window may become unacceptably small. Another strategy is to reduce the frame rate. The data rate is also proportional to frame rate. A frame rate of 30 frames per second is considered normal and can reproduce most motion effects satisfactorily. However, the frame rate can, in certain instances, be reduced to 15 frames per second, which results in a fifty-percent reduction in data rate.

Currently, when transmitting real-time video and audio data to a number of different receivers, the transmitter uses a least common denominator solution. If any user has a lower bandwidth channel than another, then all users of the system must receive data according to the lowest bandwidth available to any one receiver. Receivers with higher bandwidth connections must receive data that is less than optimum in terms of frame rate, image size, or image quality.

SUMMARY OF THE INVENTION

In light of the limitations described above, a need exists for a method and system for transmitting data to a number of receivers at the optimum data rate for the bandwidth of each particular receiver.

Accordingly, the present invention provides a method and system for transmitting data to a number of receivers at the optimum data rate for the bandwidth of each particular receiver by allowing the receiver to select the data rate and quality.

For the method of the invention, data is decomposed into one or more frames, and each one of the frames may also be decomposed into bands. Each one of the bands provides data in addition to the data provided by the preceding band. One or more channels are established, and the frames and/or bands are transmitted on the channels. Each frame and/or band may be transmitted on a different channel. The frames and bands may be grouped into sets, and each set may be transmitted on a different channel. The frames and bands may also be packaged into multicast datagrams. The multicast datagrams are assigned multicast addresses and may be transmitted to the multicast addresses on different channels. One or more of the channels are received, and the data is composed from the frames, bands, sets, or multicast datagrams provided on the received channels.

The system embodying the invention includes a sending terminal having a data decomposer to divide a data stream into fixed blocks of data, a compressor to compress the fixed blocks of data, and a channel generator to create one or more channels. The sending terminal may transmit the fixed blocks of data at different rates and/or on different channels. The sending terminal may also divide the data stream into bands, including a base band and subsequent bands. Each one of the subsequent bands provides data in addition to the base band and the data provided by the preceding band. The system includes a communication link coupled to the sending terminal. The communication link has a particular bandwidth. The system includes one or more receiving terminals coupled to the sending terminal via the communication link. Each receiving terminal receives the fixed blocks of data and/or the bands over one or more of the channels depending on the bandwidth Of the communication link. The receiving terminal composes the data from the fixed blocks of data, bands, or multicast datagrams received on the channels.

Various other features and advantages of the invention are set forth in the following drawings, detailed description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and IB illustrate a system embodying one form of the invention.

FIG. 2 illustrates a channel allocation scheme according to one form of the invention.

FIG. 3 illustrates an alternative channel allocation scheme according to one form of the invention.

FIG. 4 illustrates the operation of the system of FIGS. 1A and IB according to the alternative channel allocation scheme of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Before embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including" and "comprising" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

FIG. 1A illustrates a system 11 embodying one form of the invention. The system 11 includes at least one sending terminal 13 and one or more receiving terminals 15 coupled to a network 17. FIG. IB further illustrates the sending terminal 13, which includes a data decomposer 14, a compressor 16, and a channel generator 18. The data decompressor 14 of the sending terminal 13 processes a video data stream by decomposing the stream into frames. The compressor 16 then performs progressive image compression on one or more of the frames. Preferably, the compressor 16 uses the Joint Photographic Experts Group (JPEG) technique or a wavelet compression technique in which the image is divided into a series of scans or bands. The first or base band shows the image at a relatively-low quality setting. Each subsequent band improves the quality of the image by adding data to the data provided by the preceding bands. The sending terminal 13 transmits the bands individually or in groups at various frame rates on various channels. The sending terminal 13 may be a desktop or laptop computer, a personal or palm computing device, a phone, a gaming device, an Internet appliances, or any other device capable of communicating over any type of network. The sending terminal 13 is interfaced to the network 17 through suitable network interface hardware. In the case of a computer directly connected to the network 17, appropriate network interface hardware, such as an Ethernet card, is provided. In the case of a computer that accesses the network 17 through an Internet service provider (ISP) and a dial-up connection, appropriate network interface hardware, such as a modem, is provided.

As shown in FIG. 1 A, the system 11 includes one or more receiving terminals

15. Each receiving terminal 15 may have a different bandwidth connection to the network 17. For example, a receiving terminal 15a may have a 100 Mbps fast Ethernet connection, a receiving terminal 15c may have a 10 Mbps cable modem connection, and a receiving terminal 15n may have a 1.544 Mbps Tl connection. The receiving terminals 15 may be desktop or laptop computers, personal or palm computing devices, phones, gaming devices, Internet appliances, or any other devices capable of communicating over any type of network. The receiving terminals 15 are interfaced to the network 17 through suitable network interface hardware. In the case of a computer directly connected to the network 17, appropriate network interface hardware, such as an Ethernet card, is provided. In the case of a computer that accesses the network 17 through an Internet service provider (ISP) and a dial-up connection, appropriate network interface hardware, such as a modem, is provided.

The network 17 may be connected to the sending terminal 13 and the receiving terminals 15 through local area networks (LANs), wide area networks (WANs), public switched telephone networks (PSTNs), or any other type of network connections. The network 17 may also include connection-based networks, such as those using asynchronous-transfer mode (ATM) technology. The network 17 itself may be built according to any networking technology or topology or combinations of technologies and topologies. For example, the network 17 may include packet- switched networks, such as the Internet, or circuit-switched networks, such as an asynchronous transfer mode (ATM) network.

If the network 17 is a packet-switched network, such as a network using transfer control protocol/Internet protocol (TCP/IP), the sending terminal 13 generates one or more channels by creating multicast datagrams each addressed to a multicast address. As used hereinafter, the term "user" refers to one who sends video data via the sending terminal 13 or receives video data via one or more of the receiving terminals. A user of a receiving terminal 15 subscribes to a channel by becoming a member of the multicast group associated with the multicast address. A user of a receiving terminal 15 is free to join or leave a multicast group at any time. Routers (not shown) within the network 17 employ a group membership protocol to detect the presence of group members on the sub-networks that are directly attached to each router. When a user of a receiving terminal 15 subscribes to a channel, the receiving terminal 15 transmits a group membership protocol message for the group the user wishes to join. The receiving terminal 15 also sets its Internet protocol processes and network interface card to receive packets addressed to the multicast addresses of the group.

If the network 17 is a circuit-switched network, the sending terminal 13 generates one or more channels on one or more virtual circuits. The receiving terminals 15 subscribe to the channels that are appropriate to their bandwidth connection on the virtual circuits. FIG. 2 illustrates one preferred channel allocation scheme. By way of example only, the sending terminal 13 transmits the data to each one of the receiving terminals 15 in three bands and at one of three frame rates (e.g., a high frame rate of thirty frames per second, a medium frame rate of fifteen frames per second, and a low frame rate often frames per second). The data decomposer 14 within the sending terminal 13 decomposes the video data stream to generate thirty frames per second. The sending terminal 13 transmits each one of the frames to the receiving terminal 15 for the thirty-frames-per-second frame rate. The sending terminal 13 transmits every other frame to the receiving terminal 15 for the fifteen-frames-per-second frame rate. Similarly, the sending terminal 13 transmits every third frame to the receiving terminal 15 for the ten-frames-per-second frame rate.

The data decomposer 14 of the sending terminal 13 may also decompose each frame into bands, including a base band and subsequent bands. The first subsequent band adds data to the base band. Each of the other subsequent bands add data to the sum of the base band and each of the preceding bands. In the preferred channel allocation scheme shown in FIG. 2, the data decomposer 14 generates three bands. However, the data decomposer 14 may generate more or less than three bands.

Referring to FIGS. 1A and 2, the sending terminal 13 transmits Band 1 frames at the low frame rate on Channel A. Thus, on Channel A, the sending terminal 13 provides video data having relatively low image and motion quality to the receiving terminals 15. On Channel I, the sending terminal 13 transmits the sum of Bands 1, 2, and 3 at the high frame rate to provide video data with the highest image and motion quality to the receiving terminals 15. While Channel I provides substantially better image and motion quality than Charmer A, the receiving terminal 15 must have approximately nine-times as much bandwidth as required to receive Channel A.

The user of the receiving terminals 15 may trade image quality against motion quality. For example, by subscribing to Channel C, the receiving terminal 15 receives a low quality image with high quality motion, which is suitable when the motion is more important to the user than the quality of the image. Conversely, the user of the receiving terminal 15 may subscribe to Channel G when image quality is more important to the user than motion quality. For example, the user of the receiving terminal 15 may subscribe to Channel C if the video content is the head of a person or persons who are talking, i.e., "talking heads." Alternatively, the user of the receiving terminal 15 might subscribe to Channel G if the video content is a map, chart, or document with little or no motion. Preferably, the receiving terminal 15 can change channels in real-time simply by leaving and joining appropriate multicast groups in order to receive the quality image and motion that best suits the user's current needs.

FIG. 3 illustrates an alternative channel allocation scheme. By way of example only, the sending terminal 13 transmits data to the receiving terminals 15 in three bands and at three frame rates. In contrast to the channel allocation scheme of FIG. 2, the sending terminal 13 transmits each of the three bands separately. Thus, in order to obtain higher resolution images, the receiving terminal 15 must subscribe to multiple channels. For example, in order to receive the highest quality image at the highest frame rate, the receiving terminal 15 must subscribe to Channels 7, 8, and 9.

In the channel allocation schemes of FIGS. 2 and 3, the sending terminal 13 processes the frames as images, without compressing the motion from frame to frame. However, the method of the present invention may be applied to systems in which motion compression is used. Motion compression relies on the redundancy from frame-to-frame to reduce the data required to be transmitted. The sending terminal 13 divides the video data stream into "key" frames providing full images and

"difference" frames providing information regarding the change from one frame to the next. The receiving terminal 15 uses the difference frames to construct images between the key frames.

FIG. 4 illustrates a preferred embodiment of the operation of the system 11 of FIGS. 1A and IB. Referring to FIGS. 1A, IB, and 4, an original video stream 21 is input to the compressor 16, which preferably includes a video compressor 23, within the sending terminal 13. The video compressor 23 may be a software or hardware- based data compressor suitable for compressing video data. The video compressor 23 decomposes the frames of the original video stream into Bands 1, 2, and 3. For the operation of the invention as illustrated in FIG. 4, the Bands 1, 2, and 3 are allocated by the sending terminal 13 to Channels 1 through 9 according to the channel allocation scheme of FIG. 3. However, the Bands 1, 2, and 3 may be allocated to Channels A through I according to the channel allocation scheme of FIG. 2, or according to any other suitable channel allocation scheme.

Preferably, each of the receiving terminals 15 includes a video decompressor

25. The video decompressors 25 may be software or hardware-based data decompressors suitable for decompressing video data. The user of each of the receiving terminals 15 subscribes to one or more channels appropriate to the bandwidth of the communication link 20 to the network 17. For example, the receiving terminal 15a is associated with a video decompressor 25a and is connected to the network 17 by a low-bandwidth connection 27a. If the user of the receiving terminal 15a associated with the video compressor 25a requests a low-resolution, high-frame-rate video stream, the receiving terminal 15a subscribes to Channel 7. On the other hand, if the user of the receiving terminal 15d associated with a video compressor 25 d, which is also connected to the network 17 by a lόw-bandwidth connection 27d, requests a high-resolution, low-frame-rate video stream, the receiving terminal 15d subscribes to Channels 1, 2, and 3. Rather than the user of the receiving terminal 15 specifying the resolution and frame rate of the video data stream being received, the sending terminal 13 or the receiving terminal 15 may automatically adjust which channels the receiving terminal 15 is subscribed to according to the type of video data stream.

The method and system of the present invention have been illustrated and described with respect to presently preferred embodiments. Those skilled in the art, given the benefit of the foregoing disclosure, will recognize alternative embodiments. Certain features to the invention may be implemented independently of other features, all as would be apparent to one of ordinary skill in the art. Accordingly, the foregoing is intended for purposes of illustration and not of limitation.

Claims

CLAIMSWHAT IS CLAIMED

1. A method of transferring data with receiver-selectable quality of service, the method comprising:

decomposing the data into a plurality of bands, each one of the plurality of bands adding data to the data provided by a preceding one of the plurality of bands;

establishing a plurality of channels; and

transmitting the plurality of bands on the plurality of channels.

2. The method of claim 1, wherein transmitting the bands on the plurality of channels includes transmitting each one of the plurality of bands on a different one of the plurality of channels.

3. The method of claim 2, and further comprising:

receiving a selected number of the plurality of bands on a selected number of the plurality of channels; and

composing data from the selected number of the plurality of bands received on the selected number of the plurality of channels.

4. The method of claim 1, and further comprising grouping the plurality of bands into a plurality of band sets, and wherein transmitting the plurality of bands on the plurality of channels includes transmitting each one of the plurality of band sets on a different one of the plurality of channels.

5. The method of claim 4, wherein the data is an image, and further comprising:

receiving the plurality of band sets on a selected number of the plurality of channels; and composing an image from the plurality of band sets received on the selected number of the plurality of channels.

6. The method of claim 1, and further comprising:

packaging the plurality of bands into a plurality of multicast datagrams; and

assigning the plurality of multicast datagrams to a plurality of multicast addresses.

7. The method of claim 6, wherein transmitting the plurality of bands on the plurality of channels includes transmitting each one of the plurality of multicast datagrams to a different one of the plurality of multicast addresses on a different one of the plurality of channels.

8. The method of claim 7, and further comprising subscribing to at least one of the plurality of multicast addresses.

9. The method of claim 1, wherein transmitting the plurality of bands on the plurality of channels includes transmitting the plurality of bands on at least one ATM virtual circuit.

10. The method of claim 9, and further comprising subscribing to at least one ATM virtual circuit.

11. A method of transferring a video data stream with receiver-selectable video quality of service, the method comprising:

decomposing the video data stream into a plurality of frames;

establishing a plurality of channels; and

transmitting each one of the plurality of frames at a different one of a plurality of frame rates on a different one of the plurality of channels.

12. The method of claim 11, and further comprising:

receiving at least one of the plurality of channels; and

composing a video stream from the plurality of frames received on the at least one of the plurality of channels.

13. The method of claim 11 , and further comprising:

packaging the plurality of frames into a plurality of multicast datagrams; and

assigning each one the plurality of multicast datagrams to a different one of a plurality of multicast addresses.

14. The method of claim 13 , wherein transmitting each one of the plurality of frames includes transmitting each one of the plurality of multicast datagrams to a different one of the plurality of multicast addresses on a different one of the plurality of channels.

15. The method of claim 14, and further comprising subscribing to at least one of the plurality of multicast addresses.

16. The method of claim 11 , wherein transmitting each one of the plurality of frames includes transmitting each one of the plurality of frames over at least one ATM virtual circuit.

17. The method of claim 11 , and further comprising: decomposing at least one of the plurality of frames into a plurality of bands, each one of the plurality of bands adding data to the data provided by a preceding one of the plurality of bands; and

transmitting each one of the plurality of bands on a different one of the plurality of channels .

18. A method of transferring a video data stream with receiver-selectable image and motion quality of service, the method comprising:

decomposing the video data stream into a plurality of frames;

decomposing at least one of the plurality of frames into a plurality of bands, each one of the plurality of bands adding data to the data provided by a preceding one of the plurality of bands;

establishing a plurality of channels; and

transmitting each one of the plurality of bands at a different one of a plurality of frame rates on a different one of the plurality of channels.

19. The method of claim 18, and further comprising:

receiving at least one of the plurality of channels;

composing a set of frames from the plurality of bands received on the at least one of the plurality of channels; and

composing a video stream from the set of frames.

20. A method of transferring video data over a network with receiver- selectable image and motion quality of service, the method comprising:

decomposing the video data into a plurality of data frame sets, each one of the plurality of data frame sets having a different one of a plurality of image qualities and a different one of a plurality of frame rates;

establishing a plurality of channels; and

transmitting each one of the plurality of data frame sets on a different one of the plurality of channels.

21. The method of claim 20, and further comprising:

receiving at least one of the plurality of channels; and

composing video data from the plurality of data frame sets received on the at least one of the plurality of channels.

22. The method of claim 20, wherein decomposing the video data into a plurality of data frame sets includes decomposing at least one of the plurality of data frame sets into a plurality of bands, each one of the plurality of bands adding data to the data provided by a preceding one of the plurality of bands.

23. A system for transmitting a data stream with a receiving-terminal- selectable quality of service, the system comprising:

a sending terminal having

a data decomposer to divide the data stream into a plurality of fixed blocks of data,

a compressor to compress at least one of the plurality of fixed blocks of data, and

a channel generator to create a plurality of channels;

a communication link coupled to the sending terminal, the communication link having a bandwidth; and

a receiving terminal coupled to the sending terminal via the communication link and operable to receive the plurality of fixed blocks of data over at least one of the plurality of channels based on the bandwidth of the communication link.

24. The system of claim 23, wherein the data stream includes an image.

25. The system of claim 23, wherein the sending terminal transmits each one of the plurality of fixed blocks of data to the receiving terminal at a different one of a plurality of rates on a different one of the plurality of channels.

26. The system of claim 23, wherein the data decomposer is operable to divide the data stream into a plurality of bands.

27. The system of claim 26, wherein the compressor is operable to generate a base band and a plurality of subsequent bands, and wherein each one of the plurality of subsequent bands adds data to the data provided by the base band and by a preceding one of the plurality of subsequent bands.

28. The system of claim 23, wherein the channel generator is operable to open a plurality of virtual circuits .

29. The system of claim 23, wherein the receiving terminal is operable to select at least one of the plurality of channels over which to receive the plurality of fixed blocks of data.

30. The system of claim 29, wherein the receiving terminal is operable to compose a complete data package from the plurality of fixed blocks of data received over the at least one of the plurality of channels.

31. A sending terminal for a receiving-terminal-selectable quality of service data transmission system, the sending terminal comprising:

a data decomposer to divide a data stream into a plurality of data bands;

a compressor to generate from the plurality of data bands a base band and a plurality of subsequent bands, each one of the plurality of subsequent bands adding data to the data provided by the base band and by a preceding one of the plurality of subsequent bands; and

a channel generator to create a plurality of channels over which the plurality of data bands are transmitted.

32. The sending terminal of claim 31 , wherein each one of the plurality of data bands is transmitted at a different one of a plurality of rates on a different one of the plurality of channels.