Efficient Transmission Techniques for Digital Mobile Cellular and Digital Broadcast Applications

该项目有三个具体的研究领域：高效的基于信道的均衡，通过根据嵌入的训练数据得出的信道特征计算均衡器；针对码分多址、远近和码间干扰以及来自不同用户的干扰的干扰抑制；以及用于广播传输的多载波方法，用于缓解时变衰落效应。本文研究的重点是时变多径数据信道。在相对较低的数据速率下，无线通信信道的时变特性经常导致在少量符号间隔上的信道变化。在这种情况下，可以在发送的数据分组中嵌入大量的训练数据，以使得能够在接收器处进行调整。可能出于对更高数据速率的需要，另一种选择是增加传输信号的带宽。因此，与符号速率相比，信道变化的相对速率更小，并且减少了训练的分数。随着带宽的扩大，多径效应变得更加重要，需要使用更复杂的接收器结构。这项研究同时研究了窄带和宽带传输，用于数字蜂窝无线电和数字广播频道。

This project has three specific areas of study: Efficient Channel-Based Equalization, the computation of the equalizer via channel characterization derived from embedded training data; Interference Rejection for Code-Division Multiple Access, near-far and intersymbol interference and interference from disparate users; and Multicarrier Methods for Broadcast Transmission, for mitigation of time-varying fading effects. The focus of the study is on the time-varying multipath data channel. At relatively low data rates, the time-varying nature of wireless communication channels often leads to channel variation over a small number of symbol intervals. In this case a significant amount of training data can be embedded in the transmitted packets of data to enable adjustments to be made at the receiver. An alternative, perhaps forced by the need for higher data rates, is to increase the bandwidth of the transmitted signal. Then the relative rate of channel variation is less compared to the symbol rate, and the fraction of training is reduced. As wider bandwidths are used, multipath effects become more important and more sophisticated receiver structures need to be used. The research studies both narrow and wideband transmission, for applications in digital cellular radio and digital broadcast channels.