Real-time comparison of quality of interfaces

• US 20060227717A1
• Filed: 08/23/2005
• Published: 10/12/2006
• Est. Priority Date: 03/17/2005
• Status: Active Grant

• Current Assignee: Four Batons Wireless LLC (Two Gold Capital LLC)
• Original Assignee: Telcordia Incorporated, Toshiba Corporation
• Inventors: Zhang, Tao, van den Berg, Erick, Madhani, Sunil
• Granted Patent: US 7,885,185 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 45/26 Route discovery packet
• CPC Class Codes: H04W 40/12 based on transmission quality or channel quality
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In some embodiments, a system and method for substantially real-time comparison of quality of interfaces by mobile devices over heterogeneous networks is disclosed. The method can be performed using a dynamic and rapid comparison by distributed hosts, using a minimal number of injected network packets, using minimal path quality metrics, which path quality metrics are independent of how a Qol is measured, and in a manner suitable for both wireline and wireless networks.

Claims

1. A method for substantially real-time comparison of quality of interfaces (Qols) by mobile devices over heterogeneous wireless networks, comprising:

comparing in substantially real-time the qualities of multiple interfaces using path quality metrics that are independent of how the Qol is measured, whether measured by a path through a wireless network alone or a path through both a wireless network and through a wired network, said method including comparing path quality as a quickest change detection problem for observations from a new interface or comparing path quality based on sequential two sample tests.

2. A method for substantially real-time comparison of quality of interfaces (Qols) by mobile devices over heterogeneous wireless networks, comprising:

comparing in substantially real-time the qualities of multiple interfaces using path quality metrics that are independent of how the Qol is measured, whether measured by a path through a wireless network alone or a path through both a wireless network and through a wired network, said method including performing a one-sample change point detection method or performing a non-parametric and on-line two-sample method.

3. A method for substantially real-time comparison of quality of interfaces (Qols) by mobile devices over heterogeneous wireless networks, comprising:

comparing in substantially real-time the qualities of multiple interfaces using path quality metrics that are independent of how the Qol is measured, including comparing path quality as a quickest change detection problem for observations from the new interface.

4. The method of claim 3, wherein there are a set of observations from a new interface, and said comparing includes detecting whether the mean of these observations will be higher than an average available metric value.

5. The method of claim 3, further including obtaining the observations from the old and the new interfaces unmatched at different times.

6. The method of claim 5, further including employing a cumulative sum procedure for a path quality comparison.

7. The method of claim 6, further including applying the cumulative sum procedure to solve a path quality comparison as follows:

a) from m observations on the current interface, computing the sample mean and the sample standard deviation;

b) for each new observation;

if the observation is from the current interface, update the sample mean and the sample standard deviation; and

if the observation is from the new interface, calculate

${\tilde{Z}}_n={\left({\tilde{Z}}_{n-1}+\frac{{\tilde{X}}_n}{{\widetilde{\mathrm{\sigma <br><br>}}}_1}-\tilde{k}\right)}^{+},{\tilde{Z}}_0=0$

where (x)⁺=x of x>

0, and 0 otherwise;

c) if Z_n>

h, then switch interfaces, otherwise do not switch interfaces.

8. The method of claim 5, further including treating observations from the old and the new interfaces as if they are from the same data series and determining whether a mean of this combined data series will change.

9. The method of claim 5, further including performing a one-sample change point detection method.

10. The method of claim 3, further including obtaining matched observations from the old and the new interfaces with similar times.

11. The method of claim 10, further including having paired observations, one for each interface and further including applying a cumulative sum procedure to solve a path quality comparison as follows:

a) considering the differences;

{tilde over (X)}=X−

Y_n

b) calculating;

${\tilde{Z}}_n={\left({\tilde{Z}}_{n-1}+\frac{{\tilde{X}}_n}{{\stackrel{\_}{\mathrm{\sigma <br><br>}}}_1}-\tilde{k}\right)}^{+},{\tilde{Z}}_0=0$

c) and rejecting H₀ if;

{overscore (Z)}>

{tilde over (h)}

 

for appropriate values of;

{overscore (h)} and{tilde over (k)}.

12. A method for substantially real-time comparison of quality of interfaces (Qols) by mobile devices over heterogeneous wireless networks, comprising:

comparing in substantially real-time the qualities of multiple interfaces using path quality metrics that are independent of how a Qol is measured, including comparing path qualities based on sequential two sample tests.

13. The method of claim 12, further including the mobile device having limited knowledge of the quality of the current path.

14. The method of claim 12, further including having insufficiently many measurements for an estimate of the mean quality of the current path and its variance and observations are not matched.

15. The method of claim 14, further including without the mobile device knowing values for mean and median, performing a test of which interface has a higher mean or median.

16. The method of claim 15, further including performing a test of the difference in average quality by testing for a difference in a location of samples.

17. The method of claim 16, wherein said method is non-parametric, works for unequal sample sizes, and is performed on-line.

18. The method of claim 16, wherein said method employs a Rosenbaum test.

19. The method of claim 18, wherein a test statistic T_R includes a total number of a second interface'"'"'s data points which have a value larger than a largest value in a first interface'"'"'s data points.

20. The method of claim 19, wherein if an overall maximum is not from a sample set from the second interface, then the test stops, and a null-hypothesis H₀ is not rejected in favor of H₁, and otherwise H₀ is rejected in favor of H₁ if T_R is larger than a value C(α

,n₁,n₂), calculated using the distribution of T_R.

21. The method of claim 16, wherein the method is based on the length of a high-end extreme run of samples for a second interface or a low-end extreme run of samples for a first interface.

22. The method of claim 21, further including repeating the test for a new observation or a new batch of observations.

23. The method of claim 12, further including using non-parametric approaches to test differences related to paired observations that are strongly correlated.

24. The method of claim 23, further including using a Wilcoxon sign test.

25. The method of claim 12, further including performing the two sample test even when the mobile has more than two interfaces.

26. A method for substantially real-time comparison of quality-of-interfaces by mobile devices over heterogeneous radio networks, comprising:

comparing in substantially real-time the qualities of multiple interfaces using independent Qol metrics and methods used to obtain Qol measurement, whether measured by a path through a radio network alone or a path through both a radio network and through a wired network.

27. The method of claim 26, further including performing the comparison in a manner to handle arbitrary probability distributions of the Qol.

28. The method of claim 26, further including performing the comparison in a manner to handle probability distributions not known to the mobile devices when the Qol comparison is performed.

29. The method of claim 26, further including performing the comparison in a manner taking advantage of information a mobile device accumulates on a Qol of an old interface in a manner that the mobile device needs little information on a Qol of the new interface to carry out the comparison.

30. The method of claim 29, further including performing the comparison with a number of samples over the new path significantly smaller than a number of samples needed to estimate an average available metric of the new path.

31. The method of claim 26, further including comparing an average available path metric without knowing the average path metric of a new interface first.

32. The method of claim 26, further including sending minimal probing traffic for measuring Qol so as to reduce consumption of power resources on the mobile devices and radio network bandwith.