System and method for determining the audio fidelity of calls made on a cellular network using frame error rate and pilot signal strength

• US 8,140,069 B1
• Filed: 06/12/2008
• Issued: 03/20/2012
• Est. Priority Date: 06/12/2008
• Status: Expired due to Fees

• Current Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Lall, Abhishek, Bhan, Ashish, Vargantwar, Sachin, Yarkosky, Mark, Stedman, Robert
• Primary Examiner(s): SAMS, MATTHEW C
• Application Number:
  US12/138,068
• Time in Patent Office: 1,377 Days
• Field of Search: 455 6711- 677, 455423-425, 704226-228, 704/236, 704/270, 379 102- 104
• US Class Current: 455/423
• CPC Class Codes: H04M 1/24 Arrangements for testing
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic

Abstract

The present invention provides a method and system for defining the mean opinion score (MOS) as a function of frame error rate (FER) and pilot signal strength. In an embodiment of the invention, an entity receives MOS scores that have been obtained using subjective tests for certain calls made within the network. Next, the entity receives FER and pilot signal strength samples that have been obtained for the calls for which MOS scores have been subjectively obtained. Finally, the entity calculates an equation for the MOS as a function of FER and pilot signal strength using a non-linear regression analysis.

Claims

1. A method to determine an audio fidelity of a call made on a cellular network, wherein the method is carried out by a radio access network (RAN) entity, the method comprising:

the RAN entity receiving a first input, wherein the first input comprises a plurality of subjective mean opinion scores for a plurality of calls made on a network;

the RAN entity receiving a second input, wherein the second input comprises a plurality of frame error rate values for the plurality of calls made on the network;

the RAN entity receiving a third input, wherein the third input comprises a plurality of pilot signal strength values for the plurality of calls made on the network;

transforming the plurality of frame error rate values, so as to create a plurality of transformed frame error rate values;

the RAN entity transforming the plurality of pilot signal strength values, so as to create a plurality of transformed pilot signal strength values;

the RAN entity using (i) the subjective mean opinion scores, (ii) the plurality of transformed pilot signal strength values, and (iii) the plurality of transformed frame error rate values in a non-linear regression to define an equation for an objective mean opinion score, wherein the objective mean opinion score is indicative of the audio fidelity of a call made on the network; and

the RAN entity using the equation to calculate an objective mean opinion score for a call made on the network.

2. The method of claim 1, wherein the non-linear regression is a trigonometric regression.

3. The method of claim 1, wherein transforming the plurality of frame error rate values comprises using a weighted means method to determine which of the plurality of frame error rate values are most likely to correspond to a discrete subjective mean opinion score.

4. The method of claim 1, wherein transforming the plurality of pilot signal strength values comprises using a weighted means method to determine which of the plurality of pilot signal strength values are most likely to correspond to a discrete subjective mean opinion score.

5. The method of claim 1, wherein transforming the plurality of frame error rate values comprises selecting a highest ten percent of the plurality of frame error rate values.

6. The method of claim 1, transforming the plurality of pilot signal strength values comprises selecting a highest ten percent of pilot signal strength values.

7. The method of claim 1 wherein the plurality of pilot signal strength values are measured in terms of E_C/I₀.

8. The method of claim 1, wherein receiving the third input comprises receiving a plurality of pilot strength measurement messages.

9. The method of claim 1 further comprising the RAN entity comparing the calculated objective mean opinion score to a threshold value.

10. The method of claim 9, further comprising the RAN entity triggering an alert when the calculated objective mean opinion score is outside the threshold value.

11. A system comprising:

a communication interface;

a processor;

non-transitory data storage; and

program logic stored in the non-transitory data storage and executable by the processing unit to (i) receive a first input, wherein the first input comprises a plurality of subjective mean opinion scores for a plurality of calls made on a network, (ii) receive a second input, wherein the second input comprises a plurality of frame error rate values for the plurality of calls made on the network, (iii) receive a third input, wherein the third input comprises a plurality of pilot signal strength values for the plurality of calls made on the network, (iv) transform the plurality of frame error rate values, so as to create a plurality of transformed frame error rate values, and (v) transform the plurality of pilot signal strength values, so as to create a plurality of transformed pilot signal strength values;

wherein the program logic is further arranged to use a non-linear regression analysis to define an equation for an objective mean opinion score, wherein the objective mean opinion score is indicative of the audio fidelity of a call made on the network using (i) the subjective mean opinion scores, (ii) the plurality of transformed pilot signal strength values, and (iii) the plurality of transformed frame error rate values; and

wherein the program logic is further arranged to use the equation to calculate an objective mean opinion score for a call made on the network.

12. The system of claim 11, wherein the program logic is further arranged to use a weighted means method to transform the plurality of frame error rate values.

13. The system of claim 11, wherein the program logic is further arranged to use a weighted means method to transform the plurality of pilot signal strength values.

14. The system of claim 11, wherein the non-linear regression analysis is a trigonometric regression.

15. The system of claim 11, wherein program logic is further arranged select a highest ten percent of the plurality of pilot signal strength values in order to transform the plurality of pilot signal strength values.

16. The system of claim 11, wherein program logic is further arranged select a highest ten percent of the plurality of frame error rate values in order to transform the plurality of frame error rate values.

17. A method for determine an audio fidelity of a call made on a cellular network, wherein the method is carried out by a radio access network (RAN) entity, the method comprising:

the RAN entity receiving a first input, wherein the first input comprises a plurality of subjective mean opinion scores for a plurality of calls made on a network;

the RAN entity receiving a second input, wherein the second input comprises a plurality values selected from the group consisting of (i) frame error rate values for the plurality of calls made on the network and (ii) pilot signal strength values for the plurality of calls made on the network;

the RAN entity transforming the second input values, so as to create a plurality of transformed values;

the RAN entity using the subjective mean opinion scores and the plurality of transformed values in a linear regression to define an equation for an objective mean opinion score, wherein the objective mean opinion score is indicative of the audio fidelity of a call made on the network; and

the RAN entity using the equation to calculate an objective mean opinion score for a call made on the network.

18. The method of claim 17, wherein transforming the second input values comprises selecting a highest ten percent of the second input values.

19. The method of claim 17, wherein transforming the second input values comprises selecting a lowest ten percent of the second input values.

20. The method of claim 17, wherein the pilot signal strength values are measured in terms of E_C/I₀.