ITR: Differential Modulation in Space and Time

第三代和第四代蜂窝系统的目标之一是向高度移动的用户提供宽带数据接入。利用发射机或接收机处存在的多个天线的空时传输策略最近被引用为实现这一目标所需的关键技术之一。虽然近年来在空时编码和调制方面取得了很大的进展，但大多数工作都假设在接收机处可以获得完美的信道估计。然而，在某些情况下，获得准确的信道估计可能是困难的或昂贵的。 这个项目的目标是设计新的空时调制策略，不需要在发射机或接收机的信道估计。其核心思想是一个新的和通用的架构差分调制使用多个天线，它可以应用于任何数量的天线和任何信号星座。遵循这种体系结构的调制技术可以被相干或非相干解调。这些技术允许接收机利用准确的信道估计时，他们是可用的，但性能下降时，估计是不可用的只有轻微的。在这里开发的工具也在一个新的角度对导频辅助空时调制，并提供了一个系统的方式来联合设计的训练符号，接收机和调制方案。该项目解决了广泛的问题，包括基本性能限制，新的调制和编码技术，以及低复杂度的接收机。这项工作的最终目标是更充分地挖掘多天线无线电信道的潜力，并在此过程中降低无线通信的功率和带宽要求。

One of the goals of third and fourth generation cellular systems is to provide broadband data access to highly mobile users. Space-time transmission strategies, which exploit the presence of multiple antennas at the transmitter or receiver, have been cited recently as one of the key technologies needed to achieve this goal. While there has been great progress on space-time coding and modulation in recent years, most of this work has assumed that perfect channel estimates are available at the receiver. In certain situations, however, it may be difficult or costly to obtain accurate channel estimates. The goal of this project is to design new space-time modulation strategies that do not require channel estimates at the transmitter or receiver. The core idea is a new and general architecture for differential modulation using multiple antennas, which can be applied to any number of antennas and any signal constellation. Modulation techniques adhering to this architecture can be demodulated coherently or noncoherently. These techniques permit the receiver to exploit accurate channel estimates when they are available, but performance degrades only slightly when estimates are not available. The tools developed here also over a fresh perspective on pilot-assisted space-time modulation and provide a systematic way to jointly design the training symbols, receivers, and modulation schemes. This project addresses a broad spectrum of issues, including fundamental performance limits, new modulation and coding techniques, and low-complexity receivers. The ultimate goal of this work is to more fully exploit the potential of multi-antenna radio channels, and in the process reduce the power and bandwidth requirements of wireless communication.