Coding and packet distribution for alternative network paths in telecommunications networks
A method and apparatus are disclosed that seek to improve the quality of service that is experienced during the transmission of a stream of packets across one or more paths. In particular, a transmitting node encodes a source stream of data (e.g., audio, video, etc.) into one or more sub-streams, and distributes those sub-streams onto multiple network transmission paths. In accordance with the illustrative embodiment of the present invention, the transmitting node evaluates the quality of service of a first network path that fails to provide a quality-of-service guarantee. When the quality of service of the first network path becomes unsatisfactory, the coding of one or more sub-streams that are being transmitted on a second network path is adjusted. In other words, the coding on a second channel is adjusted in response to the changing conditions on a first channel.
1. A method comprising:
encoding, at a first node via a processor, a source stream of data packets into a first stream using a first protocol having a first encoded data rate;
transmitting, at a first time, the first stream from the first node to a second node over a first network path between the first node and the second node;
in response to a decrease in a quality-of-service associated with the first network path at a second time later than the first time, encoding, at the first node, the source stream of data packets into a first sub-stream and a second sub-stream using a second encoding protocol having a second encoded data rate lower than the first encoded data rate;
identifying an intermediate node whose inclusion in a network path provides a known quality of service, wherein the intermediate node is located between the first node and the second node and the first network path does not traverse the intermediate node;
transmitting, from the first node to the second node, the first sub-stream over the first network path and the second sub-stream over a second network path that connects the first node and the second node via the intermediate node, wherein the second sub-stream is combined with a third sub-stream to improve a quality of a content of the second sub-stream, and wherein the third sub-stream is encoded from the source stream;
in response to a further decrease in the quality-of-service associated with the first network path at a third time later than the second time, encoding, at the first node, the source stream of data packets into a second stream using the first protocol having the first encoded data rate; and
transmitting the second data stream from the first node to the second node over the second network path.
2. The method of claim 1 , wherein the source stream is encoded in accordance with a layered coding.
3. The method of claim 1 , wherein the second encoded data rate is half the first encoded data rate.
4. The method of claim 1 , further comprising transmitting the first sub-stream and the second sub-stream on the second network path.
5. The method of claim 1 , further comprising transmitting the first sub-stream on the first network path when the quality of service of the first network path is satisfactory.
6. The method of claim 1 , wherein the first encoding protocol is a G.711 protocol, and wherein the second encoding protocol is a G.726 protocol.
7. The method of claim 1 , wherein each of the first sub-stream and the second sub-stream is configured to guarantee a basic level of reconstruction quality, and wherein combining the first sub-stream and the second sub-stream improves the reconstruction quality.
8. The method of claim 1 , wherein the first node is a source of the source stream of data packets and the second node is a destination of the source stream of data packets.
9. The method of claim 1 , further comprising:
receiving, at the first node, the source stream of data packets from a source node.
10. The method of claim 1 , wherein at least one of the decrease in the quality-of-service or the further decrease in the quality-of-service is determined by a node other than the first node.
11. The method of claim 1 , wherein the decrease in the quality-of-service and the further decrease in the quality-of-service are measured by at least one of bandwidth, error rate, latency, a derivative or associated function of bandwidth, a derivative or associated function of error rate, or a derivative or associated function of latency.
12. The method of claim 1 , wherein the second encoding protocol features an adaptive differential pulse code modulation, and wherein the first encoded data rate is 64 kilobits per second and the second encoded data rate is 32 kilobits per second.
13. A system comprising:
a processor; and
a computer-readable storage medium storing instructions which, when executed by the processor, cause the processor to perform operations comprising:
encoding, at a first node, a source stream of data packets into a first stream using a first protocol having a first encoded data rate;
transmitting, at a first time, the first stream from the first node to a second node over a first network path between the first node and the second node;
in response to a decrease in quality of-service associated with the first network path at a second time later than the first time, encoding, at the first node, the source stream of data packets into a first sub-stream and a second sub-stream using a second encoding protocol having a second encoded data rate lower than the first encoded data rate;
identifying an intermediate node whose inclusion in a network path provides a known quality of service, wherein the intermediate node is located between the first node and the second node and the first network path does not traverse the intermediate node;
transmitting, from the first node to the second node, the first sub-stream over the first network path and of the second sub-stream over a second network path that connects the first node and the second node via the intermediate node, wherein the second sub-stream is combined with a third sub-stream to improve a quality of a content of the second sub-stream, and wherein the third sub-stream is encoded from the source stream;
in response to a further decrease in the quality-of-service associated with the first network path at a third time later than the second time, encoding, at the first node, the source stream of data packets into a second stream using the first protocol having the first encoded data rate; and
transmitting the second data stream from the first node to the second node over the second network path.
14. The system of claim 13 , wherein the source stream is encoded in accordance with a layered coding.
15. The system of claim 13 , wherein the second encoded data rate is half the first encoded data rate.
16. The system of claim 13 , the computer-readable storage medium storing additional instructions which, when executed by the processor, cause the processor to perform further operations comprising:
transmitting the first sub-stream and the second sub-stream over the second network path.
17. A computer-readable storage device storing instructions which, when executed by a processor, cause the processor to perform operations comprising:
encoding, at a first node, a source stream of data packets into a first stream using a first protocol having a first encoded data rate;
transmitting, at a first time, the first stream from the first node to a second node over a first network path between the first node and the second node;
in response to a decrease in quality of-service associated with the first network path at a second time later than the first time, encoding, at the first node, the source stream of data packets into a first sub-stream and a second sub-stream using a second encoding protocol having a second encoded data rate lower than the first encoded data rate;
identifying an intermediate node whose inclusion in a network path provides a known quality of service, wherein the intermediate node is located between the first node and the second node and the first network path does not traverse the intermediate node;
transmitting, from the first node to the second node, the first sub-stream over the first network path and the second sub-stream over a second network path that connects the first node and the second node via the intermediate node, wherein the second sub-stream is combined with a third sub-stream to improve a quality of a content of the second sub-stream, and wherein the third sub-stream is encoded from the source stream;
in response to a further decrease in the quality-of-service associated with the first network path at a third time later than the second time, encoding, at the first node, the source stream of data packets into a second stream using the first protocol having the first encoded data rate; and
transmitting the second data stream from the first node to the second node over the second network path.
18. The computer-readable storage device of claim 17 , wherein the first encoding protocol is a G.711 protocol, and wherein the second encoding protocol is a G.726 protocol.
19. The computer-readable storage device of claim 17 , wherein at least one of the decrease in the quality-of-service or the further decrease in the quality-of-service is determined by a node other than the first node.