Joint Source-Channel Coding for Wireless Networks

0729210 -无线网络的联合源信道编码目前，通过无线网络对多媒体内容进行可靠、高质量的访问是一个重要的需求。这种需求源于社会对无处不在的多媒体访问的日益增长的渴望，无论是重要的医疗信息（x射线、实时患者视频）、新闻还是娱乐。在无线网络上提供这样的服务是具有挑战性的，因为无线信道受到一种被称为衰落的现象的影响，由于这种现象，从发射机到接收机的瞬时链路质量随时间、频率和位置而变化。传输端通常不知道链路质量，因此需要使用对链路质量变化具有鲁棒性的传输方案。本研究涉及设计和分析在发射机不知道瞬时链路质量的情况下，在衰落无线信道上传输模拟信号（如多媒体信号）的有效编码方案。特别强调的技术是有效的广播信号，许多用户具有不同的链路质量和技术，允许重建质量在接收器优雅的规模与链路质量。本文主要研究了广播信道和非遍历无线信道的联合信源信道编码方案的设计和分析。本研究解决的具体问题包括：(1)设计了几种基于分层传输和叠加编码的新型联合源信道编码方案、带或不带侧信息的混合数模编码以及匹配串联编码的使用。这些代码设计用于多输入多输出信道，单输入单输出高斯和擦除广播信道，以及存在发射器已知而接收器未知的干扰的单输入单输出广播信道。（ii）开发工具，以了解这些方案的潜力和基本限制，并定义适当的指标，这些指标在分析上易于处理且具有洞察力。(3)构建可实际实现的联合源信道码。特别注意的是，当与实际编码/解码算法一起使用时，而不是在假设的最大似然解码下，构建一个中等长度的单一代码，同时是一个好的源代码和一个好的信道代码。

0729210 - Joint Source-Channel Coding for Wireless NetworksCurrently, there is a significant demand for reliable, high-quality access to multimedia content over wireless networks. This demand stems from society's growing desire for ubiquitous access to multimedia, whether it be critical medical information (x-rays, real-time patient video), news, or entertainment.Providing such services over wireless networks is challenging because wireless channels are subject to a phenomenon known as fading, due to which the instantaneous link quality from the transmitter to the receiver varies with time, frequency and location. The link quality is often not known at the transmitter, necessitating the use of transmission schemes that are robust tochanges in the link quality. This research involves the design and analysis of efficient encoding schemes for transmission of analog signals such as multimedia signals over fading wireless channels, when the instantaneous link quality is not known at the transmitter. Particular emphasis is placed on techniques which are efficient for broadcasting signals to many users with different link qualities and techniques that allow the reconstruction quality at the receiver to scale gracefully with the link quality.This research focusses on the design and analysis of joint source-channel coding schemes for broadcast channels and non-ergodic wireless channels. Specific problems addressed in the research include - (i) the design of several novel joint source-channel coding schemes based on layered transmission with superposition coding, hybrid digital-analog coding with and without side information and the use of matched tandem-encoding. Such codes are designed for multiple-input multiple-output channels, single-input single-output Gaussian and erasure broadcast channels, and a single-input single-output broadcast channel in the presence of an interference known to the transmitter and unknown to the receiver. (ii) development of tools to understand the potentials and fundamental limits of these schemes, and in the definition of appropriate metrics that are analytically tractable as well as insightful. (iii) construction of practically realizable joint source-channel codes. Particular attention is given to the construction of a single code of moderate length that is simultaneously a good source code and a good channel code when used with practical encoding/decoding algorithms, instead of under hypothetical maximum-likelihood decoding.