Route referencing and ordering for synchronization-free delay tomography in wireless networks

Abstract

Delay tomography is an inference technique for link delays in a network, where end-to-end route measurement is a promising method to reduce measurement overhead. Furthermore, by incorporating compressed sensing, delay tomography can efficiently detect sparse anomaly. In delay tomography, however, there is an inevitable issue that is clock synchronization for the route measurements. In this paper, based on route referencing, we study synchronizationfree delay tomography with compressed sensing. From theoretical analysis, optimal route referencing and ordering methods for synchronization-free delay tomography are derived as "subtractive and differential schemes," which cancel or minimize the error factors caused by clock asynchronism, clock skew, and normal link delays with single or multiple references, respectively. Simulation experiments confirm that the proposed methods can identify abnormal links more accurately with robustness against the error factors than a conventional scheme, where the newly proposed differential scheme always shows the best performance thanks to its better error factors cancelation.

Optimal Estimation of Link Delays based on End-to-End Active Measurements

“…This solution not only adds a lot of overhead but also has clock synchronization issue. Because of that the authors of [16] study synchronization-free delay measurement. In this way, they use theoretical analysis to cancel or minimize the error factors caused by clock asynchronism.…”

“…Besides, they have some considerations which rarely stands for real-world networks. It is worth mentioning that although we are seeking to solve the same problem [18] and [16] are trying to, the solutions/approaches are completely different, i.e., our work is not an extension of these works. In our work, we use loops to overcome with the clock synchronization issue.…”