The overlay network approach is an emerging technique to satisfy the strict requirements for various real-time multimedia services. However, overlay networks suffer from a shared congestion problem since each unicast flow may interfere with each other in the common underlying links. Most previous techniques to detect shared congestion have limitations when applied as a general solution, since they assume perfect synchronization between probing packets. However, our recent work shows that a technique based on wavelet denoising can overcome the limitations by mitigating the interfering effects such as synchronization offset and the random fluctuations of queueing delay; the proposed technique provides a more robust and accurate detection in the presence of a large amount of synchronization offset In this paper, wavelet denoising is tailored to the characteristics of queueing delay on packet networks. The wavelet denoising based technique is verified through extensive simulations. The efficacy of the proposed approach is demonstrated by the detection accuracy and convergence speed.