Graduation Year

2003

Document Type

Thesis

Degree

M.S.E.E.

Degree Granting Department

Electrical Engineering

Major Professor

Moreno, Wilfrido

Keywords

matlab, layered internet

Abstract

Traditional telephony networks with their cumbersome and costly infrastructures are being replaced with voice being transmitted over the Internet. The Internet is a very commonly used technology that was traditionally used to transmit data. With the availability of large bandwidth and high data rates the transmission of data, voice and video over the Internet is gaining popularity. Voice is a real time application and the biggest problem it faces is the loss of packets due to network congestion. The Internet implements protocols to detect and retransmit the lost packets. However, for a real time application it is too late before a lost intermediate packet is retransmitted. This causes a need for reconstruction of the lost packet. Therefore, good reconstruction techniques are being researched. In this thesis a new concealment algorithm to reconstruct lost voice packets is reported.

The algorithm is receiver based and its functionality is based on Time Scale Modifications of speech and autocorrelation of a speech signal. The new techniqhe is named the Modified Waveform Similarity Overlap Add , (WSOLA) technique. All simulations were performed in MATLAB.

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