Quality of service monitor for multimedia communications system

• US 6,741,569 B1
• Filed: 04/18/2000
• Issued: 05/25/2004
• Est. Priority Date: 04/18/2000
• Status: Expired due to Term

• Current Assignee: Telchemy Incorporated
• Original Assignee: Telchemy Incorporated
• Inventors: Clark, Alan Douglas
• Primary Examiner(s): HO, DUC CHI
• Application Number:
  US09/551,498
• Time in Patent Office: 1,498 Days
• Field of Search: 370/230, 370/235, 370/252, 370/259, 370/229, 370/260, 370/255, 370/333, 370/394, 370/389, 370/352-357, 370/469, 370/466, 370/401, 370/516, 370/517, 455/414, 455/67.1, 379/88.13, 379/88.17, 379/202.01, 379/201.01, 704/200, 704/206, 375/228, 375/224, 709/230-235
• US Class Current: 370/252
• CPC Class Codes: G10L 25/69 for evaluating synthetic or decoded voice signals
• CPC Class Codes: H04L 41/142 using statistical or mathematical methods
• CPC Class Codes: H04L 41/5003 Managing SLA; Interaction between SLA and QoS
• CPC Class Codes: H04L 41/5087 wherein the managed service relates to voice services management of VoIP services H04M7/0081
• CPC Class Codes: H04L 43/0835 One way packet loss
• CPC Class Codes: H04L 43/0858 One way delays
• CPC Class Codes: H04L 43/087 Jitter
• CPC Class Codes: H04L 43/12 Network monitoring probes
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/24 Traffic characterised by specific attributes, e.g. priority or QoS
• CPC Class Codes: H04L 47/43 Assembling or disassembling of packets, e.g. segmentation and reassembly [SAR]
• CPC Class Codes: H04L 65/1026 at the edge
• CPC Class Codes: H04L 65/1036 at the edge
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/765 intermediate
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04M 3/2227 Quality of service monitoring
• CPC Class Codes: H04M 3/2236 Quality of speech transmission monitoring
• CPC Class Codes: H04M 7/006 : Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42

Abstract

A subjective quality monitoring system for packet based multimedia signal transmission systems estimates the parameters of a statistical model representing the probabilities of said packet based transmission system being in a low loss state or a high loss state and uses said estimates to predict the subjective quality of the multimedia signal. The quality monitoring system comprises a plurality of quality monitoring functions located at the multimedia to packet conversion points.

Claims

1. A method for automatically estimating the subjective quality of a multimedia signal transmitted over a packet connection during a single call, comprising the steps of:

(a) during a single call determining the statistical distribution of the time spent by said packet connection in at least a low packet loss probability state and a high packet loss probability state, and

(b) during that same single call determining the effect of said statistical distribution on the estimated subjective quality of said multimedia signal.

2. A method as defined in claim 1, further comprising the steps of:

(a) determining the level of one or more impairments, said one or more impairments being selected from the group consisting of jitter and delay and packet error rate and CODEC distortion, and

(b) determining the estimated effect of said one or more impairments on the subjective quality of said multimedia signal.

3. A method as defined in claim 2, further comprising the step of reporting an estimated subjective quality to a central database system following the termination of said multimedia signal.

4. A method as defined in claim 2, further comprising the steps of comparing said estimated subjective quality to a threshold and sending an event message to a central management system if said subjective quality is below said threshold.

5. A method as defined in claim 2, further comprising the insertion of a representation of the estimated subjective quality of the received multimedia signal into transmitted voice packets.

6. A method as defined in claim 2, further comprising the periodic updating of a counter wherein:

(i) when the estimated subjective quality is low, said counter is reduced by an amount dependent on said subjective quality, and

(ii) when the estimated subjective quality is high, said counter is increased.

7. A system for automatically estimating the subjective quality of a multimedia signal transmitted over a packet network during a single call wherein the multimedia signal connects two or more multimedia signal to packet conversion points and one or more of said conversion points are physically grouped within an enclosure, comprising a plurality of quality monitors for performing monitoring functions wherein:

(a) each of said functions, performed by said quality monitors one of said conversion points and each of said quality monitors is contained within the same enclosure as said conversion point;

(b) each of said functions estimates the subjective quality resulting from the conversion of received packets to a multimedia signal performed by said conversion point during a single call.

8. A system as defined in claim 7, wherein the quality monitors for performing monitoring function

(a) determines the statistical distribution of the time spent by said packet connection in at least a low packet loss probability state and a high packet loss probability state, and

(b) determines the estimated effect of said statistical distribution on the subjective quality of said multimedia signal.

9. A system as defined in claim 8, wherein the quality monitors for performing monitoring function:

(a) determines the level of one or more impairments, said one or more impairments being selected from the group consisting of jitter and delay and packet error rate and CODEC distortion, and

(b) determines the estimated effect of said one or more impairments on the subjective quality of said multimedia signal.

10. A system as defined in claim 8, wherein the quality monitors for performing monitoring function reports the estimated subjective quality of the multimedia signal to a central database system following the termination of said multimedia signal.

11. A system as defined in claim 8, wherein the quality monitors for performing monitoring function compares the estimated subjective quality of the multimedia signal to a threshold and sends an event message to a central management system if said subjective quality is below said threshold.

12. A system as defined in claim 8, wherein the quality monitors for performing monitoring function inserts a representation of the estimated subjective quality of the received multimedia signal into transmitted voice packets.

13. A system as defined in claim 8, wherein the quality monitors for performing monitoring function contains a counter wherein:

(a) when the estimated subjective quality is low, said counter is reduced by an amount dependent on said subjective quality, and

(b) when the estimated subjective quality is high, said counter is increased.

14. A system for automatically estimating the subjective quality of a multimedia signal transmitted over a packet connection during a single call, comprising:

(a) a means for determining the statistical distribution during a single call of the time spent by said packet connection in at least a low packet loss probability state and a high packet loss probability state, and

(b) a means for determining the effect of said statistical distribution during that same single call on the estimated subjective quality of said multimedia signal.

15. A system as defined in claim 14, further comprising:

(a) a means for determining the level of one or more impairments, said one or more impairments being selected from the group consisting of jitter and delay and packet error rate and CODEC distortion, and

(b) a means for determining the estimated effect of said one or more impairments on the subjective quality of said multimedia signal.

16. A system as defined in claim 15, further comprising;

a means for reporting an estimated subjective quality to a central database system following the termination of said multimedia signal.

17. A system as defined in claim 15, further comprising;

a means for comparing said estimated subjective quality to a threshold and sending an event message to a central management system if said subjective quality is below said threshold.

18. A system as defined in claim 15, further comprising;

a means for inserting a representation of the estimated subjective quality of the received multimedia signal into transmitted voice packets.

19. A system as defined in claim 15, further comprising;

a means for periodically updating a counter wherein;

(i) when the estimated subjective quality is low, said counter is reduced by an amount dependent on said subjective quality, and

(ii) when the estimated subjective quality is high, said counter is increased.