Evaluate multiple description coding as an image processing method for transferring information in error-prone networks with low transmission rate, related to quality, bit rate and file size
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Over the past several years, image transmissions and other multimedia services have become increasingly popular. The problem is that many of these services are performed in so-called unreliable transmission systems, for example wireless or mobile systems, where there is a greater probability of packet loss, bit errors and/or interference when compared to wired transmission systems. In today’s transmission systems, retransmission is a commonly used technique for the correction of lost, or erroneous, data packets. However, this technique has several shortcomings since the retransmissions often lead to a considerable amount of extra network traffic, which in turn results in a reduced availability of bandwidth for each user, and, at worst, may result in network congestion. The time spent on data retransmissions may also be a problem in several applications. This thesis evaluates MD coding as an alternative solution to the abovementioned problems. MD coding is a technique to achieve robust communication over unreliable channels such as a lossy packet network. A source is split into two or more equally important descriptions in such a way that various reconstruction qualities are obtained from different subsets of the descriptions. In MD coding, statistical redundancy is added to a data signal in such a way that data packets, which are lost or exposed to errors during transmission, can be estimated from all, or some of, the successfully received data packets. This evaluation is accomplished by development and implementation of several SD and MD coding algorithms, where the main objective is to prove that the MD coding algorithms may considerably reduce the need for retransmission in unreliable transmission systems. Since the available bandwidth in such systems is often limited, compression of image data is also an important part of this thesis. The developed coding algorithms and compression procedures are implemented through a test application, which simulates image network transmissions with user-defined parameters. Finally, the efficiency of each developed MD coding algorithm is proved by comparing them with the SD coding systems, the so-called baseline systems. Through this thesis project, it has been discovered, by means of qualitative and quantitative tests, that the MD coding systems outperform the SD coding systems when packet loss occur during image transmission, while matching the SD coding systems when all the image data are successfully transmitted. This is done by adding a certain amount of redundancy to the MD data signals.
Masteroppgave i informasjons- og kommunikasjonsteknologi 2005 - Høgskolen i Agder, Grimstad
UtgiverHøgskolen i Agder
Agder University College