Voice Quality Guaranteed Service over Best-Effort IP Network for Pervasive Environments

Pervasive computing with voice application service must be providing unprecedented levels of technology in order to adapt the continually changed computing resources in ubiquitous environment. A number of conditions differ from the speech signal over IP network with heterogeneous devices while voice traffic is transported by packet-based in ubiquitous environment. In this paper, voice signals in packet loss and noise is controlled for the guaranteed quality of service (QoS) on the IP network which are responsible for digitizing, encoding, decoding, and playing out the speech signal. We implement the algorithms of packet loss concealment (PLC) and noise reduction, which is called PEA (pervasive environment adaptation)-PLC, PEA-noise reduction together, for providing high quality voice-based pervasive computing services. The proposed PEA-PLC algorithms are applied as post-processing after decoding on devices, and then PEA-noise reduction method is applied as pre-processing before speech coding. The proposed PEA-algorithms for packet loss and noise are applied in G.729A codec optimally using mobile-softphone and a 1-port gateway PSTN phone system. The performances of the proposed methods are evaluated by the PESQ measurement in various packet loss and noisy conditions