CN1345499A - Discarding traffic in IP networks to optimize the quality of speech signals - Google Patents

Abstract

A method for discarding data within an IP-network communications link (10) in a manner that optimizes the quality of speech data contained in the IP-network communications link (10). Initially, the IP-network communications link (10) is monitored to determine the occurrence of an overload condition. At least a portion of a plurality of data packets (30) within the IP-network communications link (10) are selected in response to detection of the overload condition. The selected portions are discarded from the IP-network communications link (10), and the remainder of the packets (30) transmitted on the link (10).

Description

Dropping traffic in IP networks to optimize voice signal quality

technical field

The present invention relates to overload situations in communication links of IP networks, and in particular to a method of mitigating overload situations in communication links of IP networks in such a way that the quality of speech signals in the communication links is optimized.

Background technique

As shown in FIG. 1 , in a cellular access network 10 , signals are transmitted through an air interface part 15 and an IP transport network 20 . The IP transport network 20 moves data through the network 20 using IP network communication links. In the cellular access network 10, voice quality considerations are basically due to the degradation of the signal quality (QOS) that occurs in the air interface 15 . When compared to the QOS degradation at the air interface 15, the degradation of QOS in the IP transport network 20 must be negligible or the voice signal quality becomes unacceptable.

The major signal degradation problems that arise in the IP network communication links of the IP transport network 20 occur in certain overload situations that require the IP transport network to drop traffic. This involves dropping data packets from the IP transport network communication link. This overload condition may be caused by a link failure or other rerouting activity in the IP transport network 20 . In many cases, such as statistical multiplexing, the overload situation may only be temporary. In all these cases, however, the excess traffic must be dropped in such a way as to avoid degradation of the speech signal quality.

The technical problem that the present invention solves

Problems with existing IP-based networks arise from the fact that they are optimized for best-effort applications providing the best overall signal quality. The quality of the signal structure is optimized in a similar manner. While the quality of this signal structure may be suitable for the overall signal, the system is not necessarily suitable from a speech quality point of view. The current method is optimized in the flow control mechanism of the TCP protocol, such that routers will drop packet traffic in a random manner, enabling the system to control traffic in a fair manner by randomly dropping packets without giving special priority to any packets or related connections. While this may be acceptable for overall communication performance, it may have an adverse effect on voice signal quality.

By dropping packets in a random manner, poor performance can be introduced on the overall speech signal quality. Thus, if one or a few voice signals cause an overflow condition and initiate dropping traffic in 100 other real-time streams consisting of many voice packets, the aggregate quality of all users on these 100 real-time streams may degrade below the high Acceptable threshold for quality speech signal. Some method of limiting the consequences of overload conditions on the overall speech signal quality is needed.

The present invention overcomes the above and other problems by discarding data in an IP network communication link in a manner that optimizes voice data quality. Monitor the overload situation of the IP network communication link on the link. In response to the detected overload condition, a specific data set is selected in the IP network communication link. In a first embodiment, the packet payload of the data packets within the communication link is divided into important parameters and less important parameters. A less important parameter for selecting and discarding multiple data packets in an IP network communication link.

In a second embodiment, a selected group of data packets called real-time streaming sessions that contain the same source and destination IP address and source and destination port are selected and deleted from the IP network communication link. The data packets are composed of encapsulated video, audio and other signals. In this way, only a single or a few real-time streaming sessions need to be removed from the link, the rest of the link remains unaffected.

Brief introduction to the drawings:

For a more complete understanding of the present invention, reference is made to the following detailed description in conjunction with the accompanying drawings, wherein:

Figure 1 is a block diagram illustrating a cellular access network;

Figure 2 is a block diagram illustrating the transmission of data packets over an IP network communication link;

Figure 3 illustrates a first embodiment of the invention wherein a portion of a plurality of packet payloads is removed from a data packet in an IP network communication link;

Figure 4 is a block diagram illustrating the method of Figure 3;

Figure 5 illustrates an alternative embodiment of the present invention in which data packets from a single real-time information flow are dropped from the IP network communication link; and

FIG. 6 is a flowchart illustrating the method of FIG. 5 .

specific embodiment

Referring now to the drawings, and in particular to FIG. 2, a single IP network communication link 25 over IP transport network 20 (FIG. 1) is illustrated. At the communication link 25 are a plurality of data packets 30 including a packet header 35 containing information to enable transmission of the data packets 30 over the IP network communication link 25 and payload information 40 . Payload 40 contains information transmitted over IP network communication link 25 between source and destination addresses.

The packet header 35 includes a fixed value parameter 45 and a non-fixed value parameter 50 . A fixed value parameter changes infrequently during a call and only needs to be sent a few times during a call. The variable value parameter 50 changes frequently during the call, is coded and is always transmitted in a compressed header. This method of transmitting a fixed value only a few times during a call is called header compression. This is accomplished by including at each end of the IP network communication link 25 a record 55 that includes fixed parameters 45 that are not transmitted. Make a record of the real-time streaming process from the source address to the destination address.

Referring now to FIG. 3 , a first embodiment of the present invention is illustrated in which an overload condition detected on the IP network link 25 can be mitigated without degrading the voice signal quality of the communication link 25 (i.e. The acoustic signal perceived by the receiving end is not severely degraded). An overload condition occurs when more traffic (ie, data packets) occurs on a communication link than it can handle. During an overload condition, a plurality of data packets 30 on the IP network communication link 25 have their classifications to determine the packet payload 40 of the important parameters 70 and the less important parameters 75 contained in each data packet 30 . The specification of important and less important parameters is generally performed before or during data packing. Select and discard the less important parameter 75 in each packet payload 40 from each data packet 30 by the local router in the IP network, like this, whole data packet 30 becomes the important parameter 70 that only contains data payload 40 and Truncated data packet 30a of packet header 35. In this way each data packet 30 is transmitted as a truncated or partial packet 30a rather than the entire packet 30 as originally provided. The quality of the speech signal in the IP network communication link 25 is maintained at a high level despite the elimination of less important parameters. The division into important and less important parameters is generally performed by the signal processing protocol, but other methods of prioritizing parameters may be used.

Referring now to FIG. 4, a flowchart of the method of FIG. 3 is illustrated. In step 80, the IP network communication link 25 is monitored for the occurrence of an overload condition. As discussed above, when an overload condition is detected, the packet payload 40 in the data packet 30 is marked at step 85 with the important and less important parameters. A less important parameter is selected from the plurality of data packets 30 at step 90 and the selected less important parameter is discarded at step 95 . In an optional step, the header of the packet may also be compressed at step 100 and the truncated packet 30a is transmitted over the IP network communication link 25 at step 105 .

In an alternative embodiment, rather than a portion of the packet payload 40 within the number of data packets 30 being removed, the number of data packets 30 may be removed from the IP network communication link 25 in its entirety. In this embodiment, the local router of the IP network determines the real-time process information flow associated with each packet 30 in the IP network communication link 25 by reading the information contained in the packet header 35 . A real-time process information stream includes multiple data packets with the same source and destination IP addresses and the same source and destination ports. A real-time process flow may also include multiplexing a portion of the multiplexed data stream previously from a single data stream source. Each data packet 30 with this same information is considered to be from the same real-time process information flow.

A single IP network communication link 25 may have multiple real-time information streams associated therewith, as shown in FIG. 3 at numerals 30a, 30b, and 30c. From a speech signal quality standpoint, it is better to drop individual streams, eg 30b, of the real-time streams than to drop data packets from each real-time stream. Thus, by dropping the real-time stream indicated at 30b, the IP network communication link 25 would be transformed to include only the real-time stream shown at 30a and 30c. Although the signal of real-time stream 30b is completely lost, the signal quality of real-time streams 30a and 30c will remain unaffected. Deciding which real-time stream to drop can be determined randomly or based on a number of methods. These methods include but are not limited to dropping data packets based on the above priority in the packet header; assigning some addresses with higher priority; having control signals dynamically select parameters to be dropped; giving priority to specific bearer protocols; Or drop from the most recently connected live stream.

Referring now to FIG. 6 , there is illustrated a flow diagram describing the method of FIG. 5 . In step 120 the IP network communication link 25 is monitored for the occurrence of an overload condition. Upon detection of an overload condition, a determination of the real-time streams currently supported by the IP network communication link 25 is determined at step 125 . After determining at least one real-time information flow, at step 130 a router of the IP network selects a single real-time information flow, and at step 135 discards the selected real-time flow of the IP network communication link 25 . An optional step of packet header compression may be performed on the remaining data packets 30 at step 140 and the remaining packets transmitted over the IP network communication link at step 145 .

While preferred embodiments of the method and apparatus of the present invention have been illustrated in the drawings and described in the foregoing Detailed Description, it should be understood that the invention is not limited to the disclosed embodiments, but is capable of numerous rearrangements, modifications and substitutions without departing from the spirit of the invention as set forth and defined in the following claims.

Claims (15)

1. A method of discarding data in a manner to optimize the quality of voice data on the IP network communication link in an IP network communication link, comprising steps: Monitor the occurrence of overloading of IP network communication links; In response to an overload condition, selecting at least a portion of a plurality of data packets of the IP network communication link, wherein deletion of said selected at least one of the plurality of data packets will not substantially reduce the quality of a voice signal on the link ;and Selected portions of the plurality of data packets selected from the IP network communication link are discarded. 2. The method according to claim 1, wherein the selecting step further comprises the step of: dividing the packet payload into a first set of parameters and a second set of parameters; and A second set of parameters is selected in response to an overload condition. 3. The method of claim 2, wherein the step of discarding includes discarding a second set of parameters selected from the packet payload of the IP network communication link. 4. The method of claim 2, wherein discarding the selected parameters does not substantially degrade the acoustic signal perceived by the listener at the receiving end of the IP network communication link. 5. The method of claim 2, further comprising the step of storing a record containing the second set of parameters at each end of the IP network communication link. 6. The method according to claim 1, wherein the selecting step further comprises the steps of: determining at least one real-time streaming session over the IP network communication link; The determined at least one real-time streaming session is selected in response to the overload condition. 7. The method of claim 6, wherein the step of dropping further comprises the step of dropping the real-time streaming session selected from the IP network communication link. 8. The method of claim 6, wherein the real-time streaming session includes a set of data packets having the same source and destination IP addresses and source and destination ports. 9. The method of claim 1, further comprising the step of compressing packet headers over the IP network communication link. 10. A method of discarding data in a manner to optimize the quality of voice data on the IP network communication link in an IP network communication link, comprising the steps of: Monitor the occurrence of overloading of IP network communication links; dividing the packet payload into important parameter groups and less important parameter groups; selecting a less important parameter set in response to an overload condition; and Discarding less significant parameter sets among the plurality of data packets of the IP network communication link. 11. The method of claim 10, further comprising the step of compressing packet headers over the IP network communication link. 12. The method of claim 10, wherein discarding the less important group parameters does not substantially degrade the acoustic signal perceived by a listener at the receiving end of the IP network communication link. 13. A method for discarding data in an IP network communication link to optimize the quality of voice data on the IP network communication link, comprising the steps of: Monitor the occurrence of overloading of IP network communication links; identifying data packets with the same source and destination IP addresses and the same source and destination ports; and A determined number of data packets from the IP network communication link are discarded in response to the overload condition. 14. The method of claim 13, further comprising the step of compressing packet headers over the IP network communication link. 15. The method of claim 13, wherein discarding the determined plurality of data packets does not substantially degrade the acoustic signal perceived by a listener at the receiving end of the IP network communication link.

Images