Identification of Multi-Reflective Echo Paths using Sub-Rate Adaptive Filtering in Presence of Moderate Aliasing

Conditions for coexistence of voice and data communication have become complex, and voice aspects of telecommunication, particularly in Voice-over-IP networks, demand echo cancellers to cover all voice channels, as opposed to only long-haul channels, as it used to be in traditional public switched telephone networks. Echo path coverage requirements for the echo cancellers have become more demanding, causing an increase of computational cost of their implementations. One of the methods of decreasing that cost is via implementing sparse echo cancellers. This study explores an approach to additionally reduce computational cost at the stage of pre-processing of input signals for use in a sub-rate adaptive filter, at the expense of aliasing effects. This reduction is based on observations indicating that adaptive filters are not very sensitive to aliasing effects when it comes to detection of multiple reflections.