Decreasing distortion using low delay codes for bursty packet loss channels

The strict delay constraints of real-time communication applications in packet networks limit the use of automatic repeat request (ARQ) (retransmission systems) and error correction codes with extensive interleaving and decoding over long intervals. Since packet losses can introduce significant impairments, we study the effectiveness of low delay channel coding techniques to increase transmission quality across links with bursty losses. Specifically, we consider the benefits of the newly discovered class of low delay convolutional codes known as maximally short codes. By analyzing a Gaussian source transmitted over a Gilbert-Elliott channel, we demonstrate that these codes can achieve significant gains in comparison to uncoded transmission schemes or traditional coded schemes employing Reed-Solomon block codes. To complement and validate the theoretical analysis we also present results from informal listening tests with a voice-over-IP application.