Wave diversity in wireless communication

利用传播波的多样性是无线通信系统高效运行的关键。这种多样性发生在两个不同的维度上：空间和时间。两者都对电磁辐射所能携带的信息量构成了基本限制。本项目试图根据传播场的空间频谱的物理概念，对这些独立的轴提出统一的观点，并在信息论和电磁理论的领域之间建立联系。更具体地说，该项目从物理原理上定义了多天线信道中信息传输的概念，并研究了通过信道传输到接收器的信息量如何取决于由发射天线和环境中存在的散射物体组成的辐射系统的空间和频率带宽。通过将场重构的逆问题简化为空间中的通信问题，并通过在场的向量空间上严格应用采样定理来确定信道的相关通信模式，空间信息内容以与时间对应物类似的方式进行量化。本研究将信息率的概念从时间扩展到空间，旨在揭示这两个维度之间的基本对偶性和权衡。

Methods to exploit the diversity of propagating waves are crucial to the efficient operation of wireless communication systems. Such diversity occurs along two different dimensions: space and time. Both of them pose fundamental limits on the amount of information that can be carried by electromagnetic radiation. This project attempts to present a unified view of these separate axes, based on the physical notion of space frequency spectrum of the propagating field, and to draw connections between the fields of information theory and electromagnetic theory.More specifically, the project defines the concept of information transmission in a multiple antenna channel from physical principles, and investigates how the amount of information transported over the channel to the receiver depends on both the spatial and the frequency bandwidth of the radiating system composed by the transmitting antennas and the scattering objects present in the environment. The spatial information content is quantified in a similar fashion than its temporal counterpart, by reducing the inverse problem of field reconstruction to a communication problem in space, and determining the relevant communication modes of the channel by rigorously applying the sampling theorem on the field's vector space. This research involves extensions of the concept of information rate from time to space, and is aimed at revealing fundamental dualities and trade-offs between these two dimensions.