Title

Efficient techniques for multimedia transmission over packet-switched cellular networks

Date of Award

12-2002

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical Engineering and Computer Science

Advisor(s)

Pramod K. Varshney

Keywords

Multimedia transmission, Packet-switched, Cellular networks, Multiuser detectors

Subject Categories

Computer Engineering | Digital Communications and Networking

Abstract

In packet-switched cellular networks, base stations corresponding to different cells are connected by wired transmission links to cover the wide area, while communication in a cell takes place over wireless channels. All streams of messages are divided into packets. We consider two types of channel/link impairments in packet-switched cellular networks, bit errors and packet losses. In wireless channels, bit errors occur due to channel impairments such as fading, interference and noise. In addition, congestion at the intermediate nodes and at shared resources in wired links causes packet losses. Bit errors and packet losses are dominant impairments in packet-switching cellular networks and limit system performance. Multimedia information such as imagery and video is becoming an important part of traffic over such networks. These impairments such as bit errors and packet losses significantly impact the quality of service (QoS) of applications and degrade their performance.

In this dissertation, a number of techniques for efficient transmission of multimedia information over packet-switched cellular networks are presented. For the uplink channel in DS-CDMA systems, multiuser detection and channel decoding can be performed jointly to improve the performance of systems. We propose a new joint detection-decoding (JDD) receiver with significantly less complexity and slight reduction in performance. This joint detection-decoding receiver can be employed in multimedia applications such as image transmission for more efficient operation. The other impairments, packet losses, need to be corrected at the receiver for reliable communication. Packet-level forward error correction (FEC) schemes can be improved when they adapt to network conditions. These adaptive FEC schemes outperform the static FEC scheme in terms of the packet loss rate. Utilizing the concept of gaps that is motivated by the Markov gap model for packet losses over the Internet, adaptive FEC schemes can be further improved. We study the packet loss process and investigate its modeling using the Markov gap model. Furthermore, a gap-based adaptive FEC scheme for packet-loss recovery is proposed. We employ these new transmission approaches for image/video transmission over packet-switched cellular networks and demonstrate superior performance.

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