Method And Apparatus For Non-Intrusive Single-Ended Voice Quality Assessment In Voip

• US 20080212567A1
• Filed: 06/15/2006
• Published: 09/04/2008
• Est. Priority Date: 06/15/2005
• Status: Active Grant

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Rockstar Consortium US LP (Rockstar Consortium Inc.)
• Inventors: El-Hennawey, Mohamed, Ding, Lijing, Radwan, Ayman M., Goubran, Rafik
• Granted Patent: US 8,305,913 B2
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: G10L 25/69 for evaluating synthetic or decoded voice signals
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04M 3/2236 Quality of speech transmission monitoring

Abstract

An apparatus (1240), method, and computer program to assess VoIP speech quality (130) using access to degraded signals is provided. Different types of impairment (110) have different effect on speech quality. Preferred embodiments address up to four different types of impairment that affect VoIP signal quality: packet loss (230), speech clipping in time (850), noise (1400) and echo. An overall assessment algorithm factors in degradation due to various impairment factors to generate an overall speech quality assessment score or value.

Claims

1. A method for voice quality estimation in a VoIP system, comprising:

detecting impairment in a received VoIP signal having a series of packets, where an original signal corresponding to the received VoIP signal is unavailable;

determining degradation in the received VoIP signal caused by the impairment; and

estimate voice quality of the received VoIP signal based on the determined degradation.

2. The method in accordance with claim 1, wherein the impairment comprises packet loss, and the method further comprises:

determining a packet loss degradation component based on a packet loss profile.

3. The method in accordance with claim 2 wherein the packet loss profile comprises packet loss rate information, voiced/unvoiced information related to one or more lost packets in the series of packets and coded type information.

4. The method in accordance with claim 3 further comprising:

estimating through interpolation one or more features of each one of the one or more lost packets using packets adjacent to the lost packet in order to classify each of the one or more packets as voiced, unvoiced, or silence.

5. The method in accordance with claim 3 wherein the packet loss profile further comprises packet loss pattern information and packet loss concealment information.

6. The method in accordance with claim 2, wherein the impairment further comprises clipping, and the method further comprises:

determining a clipping degradation component.

7. The method in accordance with claim 6 further comprising:

determining individually the packet loss component and the clipping degradation component; and

calculating a combined packet loss/clipping degradation value.

8. The method in accordance with claim 6, wherein the impairment further comprises noise, and the method further comprises:

determining a noise degradation component.

9. The method in accordance with claim 8 wherein determining the noise-degradation component comprises:

estimating a speech spectrum of the received VoIP signal; and

estimating a noise spectrum of the received VoIP signal; and

calculating a signal-to-noise (SNR) ratio.

10. The method in accordance with claim 8, wherein

the impairment further comprises echo, and the method further comprises:

determining an echo degradation component.

11. The method in accordance with claim 7 wherein the combined packet/loss degradation value is calculated in a MOS domain, and the method further comprising:

calculating a voice quality MOS value based on the combined packet/loss degradation value;

converting the voice quality MOS value into an R factor in an E-model domain;

determining a signal-to-noise ratio (SNR) of the received VoIP signal; and

adjusting the R factor based on the SNR.

12. The method in accordance with claim 11 further comprising:

determining an echo degradation value; and

adjusting the R factor based on the echo degradation value.

13. The method in accordance with claim 12 further comprising:

converting the adjusted R factor to an overall MOS, value for the received VoIP signal.

14. A method for voice quality estimation in a VoIP system, comprising:

detecting impairment in a received VoIP signal having a series of packets, where an original signal corresponding the received VoIP signal is not available;

evaluating a first amount of degradation in the received VoIP signal caused by lost packets;

evaluating a second amount of degradation in the received VoIP signal caused by clipping; and

evaluating a third amount of degradation in the received VoIP signal caused by noise;

generating an overall voice quality assessment of the received VoIP signal based on the first, second and third amounts of degradation.

15. The method in accordance with claim 14 further comprising:

evaluating a fourth amount of degradation in the received VoIP signal caused by echo; and

generating the overall voice quality assessment based further on the fourth amount of degradation.

16. A telecommunications apparatus, comprising:

a processor configured to receive a VoIP signal comprising a series of packets; and

a memory, accessible by the processor, the memory storing packet data corresponding to the series of packets, wherein the processor is configured to;

detect impairment in a received VoIP signal having a series of packets, where an original signal corresponding to the received VoIP signal is unavailable,

determine degradation in the received VoIP signal caused by the impairment, and

estimate voice quality of the received VoIP signal based on the determined degradation.

17. The telecommunications apparatus of claim 16 wherein the processor is further configured to:

calculate a packet loss degradation component based on at least packet loss rate and classification of one or more lost packets in the series of packets as voiced, unvoiced or silence.

18. The telecommunications apparatus of claim 17 wherein the packet loss degradation component is further based on codec type, loss pattern, and packet loss concealment method.

19. The telecommunications apparatus of claim 17 wherein the processor is further configured to:

calculate a clipping loss degradation component based on clipping occurring in the received VoIP signal;

calculate a combined packet loss/clipping degradation value using a correlation factor; and

estimating the voice quality based on the combined packet loss/clipping degradation value.

20. The telecommunications apparatus of claim 19 wherein the processor is further configured to:

calculate a noise degradation component based on an estimated signal-to-noise ratio (SNR) of the VoIP signal; and

estimating voice quality based on the combined packet loss/clipping degradation value and the noise degradation component.