WO2009018681A1 - Apparatus and method for shaping data streaming in an xdsl network - Google Patents
Apparatus and method for shaping data streaming in an xdsl network Download PDFInfo
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- WO2009018681A1 WO2009018681A1 PCT/CN2007/002367 CN2007002367W WO2009018681A1 WO 2009018681 A1 WO2009018681 A1 WO 2009018681A1 CN 2007002367 W CN2007002367 W CN 2007002367W WO 2009018681 A1 WO2009018681 A1 WO 2009018681A1
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- buffer
- data rate
- data
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/22—Traffic shaping
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/30—Flow control; Congestion control in combination with information about buffer occupancy at either end or at transit nodes
Definitions
- the transmission apparatus includes a second buffer for receiving and buffering data packets; and a processor for adapting the data rate of sending out the buffered data packets dynamically.
- the second data rate is determined by the number of bits of packets in the second buffer divided by a predetermined period of time of fixed length.
- the data rate of sending out a data packet is adapted according to the second data rate when the second data rate is not larger than the first data rate and the first buffer is not underflow; otherwise the data rate of sending out the data packet is adapted according to the first data rate.
- the data rate of sending out the buffered data packets is a function of the number of bits of the data packets in the second buffer of the transmission apparatus.
- the transmission method further comprises steps of determining a first data rate by using the maximum send-rate that can be afforded by the network and store it; and determining a second data rate by using the maximum send-rate that can be afforded by the network, the size of the second buffer in the transmission apparatus, and the number of bits of data packets in the second buffer, and storing it.
- the second data rate is determined by using a first ratio of the size of the second buffer to the maximum send-rate that can be afforded by the network and a second ratio of the number of bits of data packets in the second buffer to the first ratio.
- the second data rate is determined by the number of bits of packets in the second buffer divided by a predetermined period of time of fixed length.
- the network is a Digital Subscriber Line network with a Digital Subscriber Line Access Multiplexer.
- the at least one data packet is received from an Ethernet Aggregation network. And the buffered data packets are sent to a Digital Subscriber Line Access Multiplexer after being processed.
- FIG.3 shows a detailed structure of the shaper used in the xDSL communication system of Fig.2;
- FIG.4 shows a flow chart illustrating an exemplary embodiment of the process of the shaper in Fig.3.
- the shaper 190 includes a buffer 310 for receiving and buffering video packets from the Ethernet Aggregation Network 120; a first memory 340 for storing the maximum send-rate r max that can be offered by the xDSL network; a second memory 350 for storing the average bit rate r ⁇ g , a processor 330 which is used to compare the maximum send-rate r max with the average bit rate r ⁇ g and transmits video streaming to the DSLAM 140 at the maximum send-rate r max or at the average bit rate r ⁇ g according to the comparison; and a packets sending out unit 320 for sending out the shaped video packets to DSLAM 140.
- the maximum send-rate r max is stored or pre-stored in the first memory 340.
- the maximum send-rate r max is calculated according to the configuration of the xDSL network such as the bit rate that can be afforded by the network. For example, in ITU-T G.992.1(G.DMT) the maximum send-rate r max of the network is 8Mbps, in ITU-T G.992.2(G.Lite) the maximum send-rate r max of the network is 1.5Mbps, and in ITU G.992.3/4 the maximum send-rate r max of the network is 12Mbps. Sometimes network providers limit the send-rate, which means the actual available bit rate of the network is lower than the ideal one. In this condition, the maximum send-rate is set according to the available one.
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Data Exchanges In Wide-Area Networks (AREA)
Abstract
An apparatus and method for transmitting data streams in an XDSL network is provided. The transmission apparatus comprises a buffer for receiving and buffering at least one data packet; a processor for adapting the bit rate of sending out each of the buffered data packets dynamically. Accordingly, the shaping method comprises steps of receiving and buffering at least one data packet; and adapting the bit rate of sending out each of the buffered data packets dynamically.
Description
APPARATUS AND METHOD FOR SHAPING DATA STREAMING IN AN
XDSL NETWORK
FIELD OF THE INVENTION
This invention relates generally to telecommunication systems and networks, and particularly to an apparatus and method for shaping data streaming in a Digital Subscriber Line network.
BACKGROUND OF THE INVENTION
In recent decades, Digital Subscriber Line (DSL) has generated particular interests in the telecommunication community. DSL enables a Public Service Telephone Network (PSTN) to deliver relatively high data bandwidth to homes and small businesses using conventional telephone company copper wiring infrastructure. xDSL refers to different variations of DSL, such as ADSL, HDSL, and RADSL.
An integral part of an xDSL communications network is referred to in the art as the Digital Subscriber Line Access Multiplexer, or "DSLAM". A DSLAM is typically located at a central office of the telephone network, and includes multiple xDSL modem ports into which client modems may connect. The primary function of the DSLAM is to multiplex client data communications from its multiple xDSL modem ports into a network, such as a LAN which may include a server and an Internet gateway. Return data communications from the network are also de-multiplexed by the DSLAM for communication to the clients via the xDSL ports.
Using xDSL to deliver internet protocol TV (IPTV) is a new emerging hot application.
Fig.l shows a traditional architecture of an IPTV system over an xDSL network 100. Video from Internet Video Source 110 can be streamed through the DSLAM 140 to clients. IPTV devices 170 at clients, e.g. Set Top Boxes or Home PCs, receive the IPTV video streaming from xDSL Modems 160 and display the video on a display such as TV 180. Conventionally, there is a buffer 150 in the DSLAM 140 to buffer video packets. However, since video streaming has a higher bit rate than voice traffic,
variable bit rate scheme is adopted to improve the efficiency of compression, and the size of buffer 150 is very limited, if the size of the buffer 150 is not enough, while the video packets are still transmitted to the subscribers, some fractions of submitted video packets will be lost. Thus the playback of IPTV services will be interrupted because of packet loss, and this will be annoying to human ears and eyes.
So it is desirable to provide an apparatus and method to reduce or even avoid the packet loss.
SUMMARY OF THE INVENTION
This invention gives a method for transmission and a corresponding device in order to smooth the data rate of transmitting the data streams and to reduce packet loss.
In an aspect, a transmission apparatus for transmitting data streams in a network having an apparatus with a first buffer is provided.
In an embodiment, the transmission apparatus includes a second buffer for receiving and buffering data packets; and a processor for adapting the data rate of sending out the buffered data packets dynamically.
In another embodiment, the processor adapts the data rate of sending out the buffered data packets as a function of the number of bits of data packets in the second buffer.
Further, the transmission apparatus comprises a first memory for storing a first data rate which is decided by the maximum send-rate that can be afforded by the network; and a second memory for storing a second data rate which is decided by the maximum send-rate that can be afforded by the network, the size of the second buffer and the number of bits of data packets in the second buffer.
Preferably, the second data rate mentioned above is decided by a first ratio of the size of the second buffer to the maximum send-rate that can be afforded by the network and a second ratio of the number of bits of data packets in the second buffer to the first ratio.
In a preferred embodiment the second data rate is determined by the number of
bits of packets in the second buffer divided by a predetermined period of time of fixed length.
In a further embodiment, the data rate of sending out the buffered data packets is adapted according to the comparison result of the first data rate and the second data rate.
Further, the data rate of sending out a data packet is adapted according to the second data rate when the second data rate is not larger than the first data rate and the first buffer is not underflow; otherwise the data rate of sending out the data packet is adapted according to the first data rate.
In a detailed embodiment, the network is a Digital Subscriber Line network with a Digital Subscriber Line Access Multiplexer. The at least one data packet is received from an Ethernet Aggregation Network. The buffered data packets are sent to the Digital Subscriber Line Access Multiplexer after being processed.
In another aspect, a transmission method performed by the transmission apparatus with a second buffer and a processor for transmitting data streams in a network having an apparatus with a first buffer is provided.
In an embodiment, the transmission method comprises steps of receiving and buffering at least one data packet in a second buffer of the transmission apparatus; and adapting the data rate of sending out the buffered data packets dynamically.
In another embodiment, the data rate of sending out the buffered data packets is a function of the number of bits of the data packets in the second buffer of the transmission apparatus.
In another embodiment, the transmission method further comprises steps of determining a first data rate by using the maximum send-rate that can be afforded by the network and store it; and determining a second data rate by using the maximum send-rate that can be afforded by the network, the size of the second buffer in the transmission apparatus, and the number of bits of data packets in the second buffer, and storing it.
Preferably, the second data rate is determined by using a first ratio of the size of the second buffer to the maximum send-rate that can be afforded by the network and a
second ratio of the number of bits of data packets in the second buffer to the first ratio.
In a detailed embodiment, the second data rate is determined by the number of bits of packets in the second buffer divided by a predetermined period of time of fixed length.
In a further embodiment, the data rate of sending out each of the buffered data packets is adapted according to the comparison result of the first data rate and the second data rate.
Further, the data rate of sending out a data packet is adapted according to the second data rate when the second data rate is not larger than the first data rate and the first buffer is not underflow; otherwise the data rate of sending out the data packet is adapted according to the first data rate.
In another embodiment, the network is a Digital Subscriber Line network with a Digital Subscriber Line Access Multiplexer. The at least one data packet is received from an Ethernet Aggregation network. And the buffered data packets are sent to a Digital Subscriber Line Access Multiplexer after being processed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG.l illustrates a conventional xDSL communication system;
FIG.2 illustrates an exemplary embodiment of an xDSL communication system according to the present invention;
FIG.3 shows a detailed structure of the shaper used in the xDSL communication system of Fig.2; and
FIG.4 shows a flow chart illustrating an exemplary embodiment of the process of the shaper in Fig.3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Fig.2 is an exemplary embodiment of an xDSL communication system with a shaper 190 being used. Though the shaper 190 is shown separated from the DSLAM 150, it can be integrated into the DSLAM 150 or other components in the xDSL
communication system 200.Fig.3 shows a detailed structure of the shaper 190 of the Fig.2. The shaper 190 includes a buffer 310 for receiving and buffering video packets from the Ethernet Aggregation Network 120; a first memory 340 for storing the maximum send-rate rmax that can be offered by the xDSL network; a second memory 350 for storing the average bit rate r^g, a processor 330 which is used to compare the maximum send-rate rmax with the average bit rate r^g and transmits video streaming to the DSLAM 140 at the maximum send-rate rmax or at the average bit rate r^g according to the comparison; and a packets sending out unit 320 for sending out the shaped video packets to DSLAM 140.
Fig.4 shows a flow chart illustrating an exemplary process of the shaper 190 in Fig.3. The reference number of the process is shown as 400 in Fig.4.
At step 410 the maximum send-rate rmax is stored or pre-stored in the first memory 340. The maximum send-rate rmax is calculated according to the configuration of the xDSL network such as the bit rate that can be afforded by the network. For example, in ITU-T G.992.1(G.DMT) the maximum send-rate rmax of the network is 8Mbps, in ITU-T G.992.2(G.Lite) the maximum send-rate rmax of the network is 1.5Mbps, and in ITU G.992.3/4 the maximum send-rate rmax of the network is 12Mbps. Sometimes network providers limit the send-rate, which means the actual available bit rate of the network is lower than the ideal one. In this condition, the maximum send-rate is set according to the available one.
At step 420, video packets are received and buffered in the buffer 310. Prior to a video packet being sent out to the DSLAM 140, the bit rate of sending out the video packet is adapted (steps 440 to 480) according to the comparison of the maximum send-rate and an average bit rate of the video packets received at the buffer at the moment. At step 430, the average bit rate of the video packets received at the buffer is calculated by the processor 330 and stored in the second memory 350. The calculation of the average bit rate of the buffered video packets, rmg is shown as below.
At first, a time window T is set. The size of time window of T is usually chosen according to the maximum send-rate rmax and the buffer size of shaper 190, i.e. T= (buffer size of the shaper)/ rmax. In our implementation, the size of time window T for
video streaming is about 3~5 seconds, and the size of time window of T for audio streaming is less than 0.1 second.
Set the average bit rate ravg= (the number of bits of packets in the buffer of the shaper)/ (time window size T). At step 440, it is determined by the processor 190 whether the calculated average bit rate rmg is larger than the maximum send-rate rmax or not. If the determination at step 440 is "yes", the bit rate of sending out the video packet is adapted to rmax at step 450 and the processor 330 sends out the video packet to the DSLAM 140 through the packet sending out unit 360 at step 480; otherwise, at step 460 the processor will detect whether the buffer 150 of the DSLAM 140 is underflow. If the buffer 150 of the DSLAM 140 is underflow, which means the buffer 150 of the DSLAM 140 is empty, i.e. the determination at step 460 is 'yes', the flow chart will go to step 450. The process following step 450 is the same as shown in the context. If the buffer 150 of the DSLAM is not underflow, i.e. the determination at step 460 is 'no', the bit rate of sending out the video packet is adapted to r^g at step 470 and the video packet is sent out at step 480. By detecting the overflow of buffer 150, the bit rate of sending out the packet will not be too low to make sure the video packets get to the decoder as needed. By choosing different bit rate to send out a video packet to the DSLAM, the bit rate at which packets arrive the DSLAM 140 will be much smoother and there are less burstnesses. Thus the risk of overflowing the buffer 150 of the DSLAM 140 will be reduced, and further the number of lost packets will be decreased.
The flow chart in Fig.4 is just for explanation the principle of the embodiment. Changes and variations made according to the principle of the embodiment still fall into the scope of the invention.
The xDSL communication system in the context refers to ADSL, ADSL2, ADSL2+, etc. Though the embodiment of the shaper is used in a xDSL network, it is also applicable to other circuit switching networks or a network in which the network streaming is needed to be shaped. Although it is described by giving an example of transmitting video streaming, the shaper and the shaping method are also applicable to other circuit switch networks.
It is to be further understood that, because some of the constituent system components and methods depicted in the accompanying drawings are preferably implemented in software, the actual connections between the system components or the process function blocks may differ depending upon the manner in which the present invention is programmed. Given the teachings herein, one of ordinary skill in the pertinent art will be able to contemplate these and similar implementations or configurations of the present invention.
Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as set forth in the appended claims.
Claims
1. A transmission apparatus (190) for transmitting data streams in a network having an apparatus (140) with a first buffer (150), characterized in that the transmission apparatus comprises a second buffer (310) for receiving and buffering data packets; and a processor (330) for adapting the data rate of sending out the buffered data packets dynamically.
2. The transmission apparatus (190) according to claim 1, wherein the processor (330) adapts the data rate of sending out the buffered data packets as a function of the number of bits of data packets in the second buffer (310).
3. The transmission apparatus (190) according to claim 1, wherein it further comprises a first memory (340) for storing a first data rate which is decided by the maximum send-rate that can be afforded by the network; and a second memory (350) for storing a second data rate which is decided by the maximum send-rate that can be afforded by the network, the size of the second buffer (310) and the number of bits of data packets in the second buffer (310).
4. The transmission apparatus (190) according to claim 3, wherein the second data rate is decided by a first ratio of the size of the second buffer (310) to the maximum send-rate that can be afforded by the network and a second ratio of the number of bits of data packets in the second buffer (310) to the first ratio.
5. The transmission apparatus (190) according to claim 3, wherein the second data rate is determined by the number of bits of packets in the second buffer (310) divided by a predetermined period of time of fixed length.
6. The transmission apparatus (190) according to claim 4, wherein the processor (330) adapts the data rate of sending out each of the buffered data packets according to the comparison result of the first data rate and the second data rate (440).
7. The transmission apparatus (190) according to claim 6, wherein the processor (330) adapts the data rate of sending out a data packet according to the second data rate when the second data rate is not larger than the first data rate and the first buffer (150) of the apparatus (140) is not underflow; otherwise adapts the data rate of sending out the data packet according to the first data rate.
8. The transmission apparatus (190) according to any of claims 1 to 7, wherein the network is a Digital Subscriber Line network and the apparatus (140) is a Digital Subscriber Line Access Multiplexer.
9. The transmission apparatus (190) according to claim 8, wherein the buffer (310) receives the data packets from an Ethernet Aggregation Network.
10. The transmission apparatus (190) according to claim 9, wherein the buffered data packets are sent to the Digital Subscriber Line Access Multiplexer (140) after being processed.
11. A transmission method (400) performed by a transmission apparatus (190) with a second buffer (310) and a processor (330) for transmitting data streams in a network having an apparatus (140) with a first buffer (150), the method comprising steps of receiving and buffering data packets (420) to the second buffer (310) of the transmission apparatus (190); and adapting (430, 440, 450, , 460, 470, and 480) the data rate of sending out the buffered data packets dynamically.
12. The transmission method (400) according to claim 11, wherein the data rate of sending out the buffered data packets is a function of the number of bits of data packets in the second buffer (310) of the transmission apparatus (190).
13. The transmission method (400) according to claim 11, wherein it further comprises steps of determining a first data rate by using the maximum send-rate that can be afforded by the network and store it (410); and determining a second data rate by using the maximum send-rate that can be afforded by the network, the size of the second buffer (310) in the transmission apparatus (190), and the number of bits of data packets in the second buffer (310), and storing it (430).
14. The transmission method (400) according to claim 13, wherein the second data rate is determined by using a first ratio of the size of the second buffer (310) to the maximum send-rate that can be afforded by the network and a second ratio of the number of bits of data packets in the second buffer (310) to the first ratio.
15. The transmission method (400) according to claim 13, wherein the second data rate is determined by the number of bits of packets in the second buffer (310) divided by a predetermined period of time of fixed length.
16. The transmission method (400) according to claim 14, wherein the data rate of sending out each of the buffered data packets is adapted according to the comparison result of the first data rate and the second data rate (440-480).
17. The transmission method (400) according to claim 16, wherein the data rate of sending out the data packet is adapted according to the second data rate when the second data rate is not larger than the first data rate and the buffer (150) of the apparatus (140) is not underflow; otherwise the data rate of sending out the data packet is adapted according to the first data rate.
18. The transmission method (400) according to any of claims 11 to 17, wherein the network is a Digital Subscriber Line network and the apparatus (140) is a Digital Subscriber Line Access Multiplexer.
19. The transmission method (400) according to claim 18, wherein the data packets are received from an Ethernet Aggregation network.
20. The transmission method (400) according to claim 19, wherein the buffered data packets are sent to the Digital Subscriber Line Access Multiplexer (140) after being processed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2007/002367 WO2009018681A1 (en) | 2007-08-07 | 2007-08-07 | Apparatus and method for shaping data streaming in an xdsl network |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2007/002367 WO2009018681A1 (en) | 2007-08-07 | 2007-08-07 | Apparatus and method for shaping data streaming in an xdsl network |
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| WO2009018681A1 true WO2009018681A1 (en) | 2009-02-12 |
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| Application Number | Title | Priority Date | Filing Date |
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| PCT/CN2007/002367 WO2009018681A1 (en) | 2007-08-07 | 2007-08-07 | Apparatus and method for shaping data streaming in an xdsl network |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1251725A (en) * | 1996-10-11 | 2000-04-26 | 夸尔柯姆股份有限公司 | Adaptive rate control for digital video compression |
| US20060050970A1 (en) * | 2004-09-08 | 2006-03-09 | Sony Corporation | Method and apparatus for transmitting a coded video signal |
-
2007
- 2007-08-07 WO PCT/CN2007/002367 patent/WO2009018681A1/en active Application Filing
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1251725A (en) * | 1996-10-11 | 2000-04-26 | 夸尔柯姆股份有限公司 | Adaptive rate control for digital video compression |
| US20060050970A1 (en) * | 2004-09-08 | 2006-03-09 | Sony Corporation | Method and apparatus for transmitting a coded video signal |
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