A New Buffer Algorithm for Speech Quality Improvement in VoIP Systems

  • Authors:
  • Zizhi Qiao;Ramesh K. Venkatasubramanian;Lingfen Sun;Emmanuel C. Ifeachor

  • Affiliations:
  • Motorola Inc., Basingstoke, UK RG24 8WQ and Signal Processing & Multimedia Communications Group, University of Plymouth, Plymouth, UK PL4 8AA;Motorola Inc., Basingstoke, UK RG24 8WQ;Signal Processing & Multimedia Communications Group, University of Plymouth, Plymouth, UK PL4 8AA;Signal Processing & Multimedia Communications Group, University of Plymouth, Plymouth, UK PL4 8AA

  • Venue:
  • Wireless Personal Communications: An International Journal
  • Year:
  • 2008

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Abstract

Jitter buffer plays an important role in Voice over IP (VoIP) applications because it provides a key mechanism for achieving good speech quality to meet technical and commercial requirements. The main objective of this paper is to propose a new, simple-to-use jitter buffer algorithm as a front-end to conventional static or adaptive jitter buffer algorithms to provide improved performance, in terms of enhanced user-perceived speech quality and reduced end-to-end delay. Supported by signal processing features, the new algorithm, the so-called Play Late Algorithm, alters the playout delay inside a speech talkspurt without introducing unnecessary extra end-to-end delay. The results show that the new algorithm achieves the best performance under different network conditions when compared to conventional static and adaptive jitter buffer algorithms. The results reported here are based on live tests and emulated network conditions on real mobile phone prototypes. The mobile phone prototypes use AMR codec and support full IP/UDP/RTP stack with IPSec function in some of the tests. The method for perceived speech quality measurement is based on the ITU-T standard for speech quality evaluation (PESQ).