Communication Through a Diffusive Medium: Coherence and Capacity

Coherent wave propagation in disordered media gives rise to many fascinating phenomena in areas as diverse as conduction of electrons through nanostructures and light scattering from granular material. It is the interference of waves coming from many different directions that produces new effects - universal conductance fluctuations in the case of mesoscopic metals and laser speckle in light scattering. In a different domain, the information-theoretic ideas of Shannon have been used to derive upper bounds on the amount of information that can be communicated through many different media, from simple wires to complicated networks. Here, we combine these two subjects for the first time: using information theory and the theory of electromagnetic propagation in diffusive media, we show how interference dramatically increases the maximum information transmission between antenna arrays. The waves propagating in many different directions in the diffusive medium interfere at the receiver array and allow it to effectively resolve the individual transmitter antennas at an arbitrary distance. This approach lays a foundation for complex microwave signal modeling, an important task in a world with ever-increasing demand for wireless communication.