Q. Gong and P. Kabal
"A New Optimum Jitter Protection for Conversational VoIP", Proc. Int. Conf. Wireless Commun., Signal Processing (Nanjing, China), 5 pp., Nov. 2009.
In Voice-over-IP, jitter buffers are introduced at both sides of the sender and the receiver to compensate for delay jitters. A longer buffer reduces the possibility of packet loss and packet disorder at the expense of increasing conversational delays. In this paper, we propose a novel criterion for the calling quality of conversational VoIP, including the effect of delay on interactivity of a conversation. Using this criterion, we propose a quality-based playout scheduling algorithm with improved voice quality and reduced conversational delays. The Simulation results show that the proposed algorithm can achieve the best calling quality compared with other algorithms.
A. H. Nour-Eldin and P. Kabal
"Combining Frontend-Based Memory with MFCC Features for Bandwidth Extension of Narrowband Speech", Proc. IEEE Int. Conf. Acoustics, Speech, Signal Processing (Taiwan), pp. 4001-4004, April 2009.
In this paper, we continue our previous work on improving Bandwidth Extension (BWE) of narrowband speech. We have shown that including memory into the parametrization frontend (through delta features) results in higher highband certainty irrespective of feature type, with MFCCs exhibiting higher correlation, in general, between both bands, reaching twice that using LSFs. By incorporating memory into the frontend of a conventional LP-based BWE system, we were able to translate the higher correlation due to memory into BWE performance improvement. Using high-resolution inverse DCT, we also achieved high quality speech reconstruction from MFCCs, thus enabling MFCC-based BWE with improved performance compared to conventional static LP-based BWE. We continue this work by incorporating the superior correlation properties of frontend memory into our MFCC-based BWE system. Log-Spectral Distortion as well as the more perceptually-correlated Itakura-based measures show that incorporating memory into our MFCC-based BWE system results in BWE performance superior to that of our dynamic LP-based BWE system.