Enabling wireless VoIP

Carrier-grade mobile Voice over Internet Protocol (VoIP) requires capacity, voice quality, and delay characteristics that equal or exceed circuit-switched designs. One challenge for enabling mobile VoIP is dealing with packets delivered at irregular intervals. Traditional receivers convert this &quo...

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Bibliographic Details
Published in:Bell Labs technical journal 2007-12, Vol.11 (4), p.201-215
Main Authors: Lee, Minkyu, McGowan, James W., Recchione, Michael C.
Format: Article
Language:English
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Summary:Carrier-grade mobile Voice over Internet Protocol (VoIP) requires capacity, voice quality, and delay characteristics that equal or exceed circuit-switched designs. One challenge for enabling mobile VoIP is dealing with packets delivered at irregular intervals. Traditional receivers convert this "jitter" into end-to-end delay and frame erasures, both of which are used to define system capacity. These state-of-the-art jitter buffers account for up to 40% of the delay budget as well as the vast majority of frame erasures. In this paper, a new paradigm is introduced where we apply signal processing techniques and psychological research to reduce this delay to zero, while greatly reducing the effects of frame erasures. We do so by introducing the concept of conversational delay, based on the observation that a user only perceives the delay of a few select voice packets. This is coupled with time scale modification and packet resynchronization to reduce delay, increase quality, and increase capacity. © 2007 Alcatel-Lucent.
ISSN:1089-7089
1538-7305
DOI:10.1002/bltj.20204