Information transfer through disordered media by diffuse waves

Abstract

We consider the information content h of a scalar multiple-scattered, diffuse wave field psi(r) and the information capacity C of a communication channel that employs diffuse waves to transfer the information through a disordered medium. Both h and C are shown to be directly related to the mesoscopic correlations between the values of psi(r) at different positions r in space, arising due to the coherent nature of the wave. For the particular case of a communication channel between two identical linear arrays of n>>1 equally spaced transmitters or receivers (receiver spacing a), we show that the average capacity <C> proportional, variant n and obtain explicit analytic expressions for <C>/n in the limit of n--> infinity and kl--> infinity, where k=2pi/lambda, lambda is the wavelength, and l is the mean free path. Modification of the above results in the case of finite but large n and kl is discussed as well. If the signal to noise ratio S/N exceeds some critical value (S/N)(c), <C>/n is a nonmonotonic function of a, exhibiting maxima at ka=mpi (m=1,2, em leader ). For smaller S/N, ka=mpi correspond to local minima, while the absolute maximum of <C>/n is reached at some ka approximately (S/N)(1/2)<pi. We define the maximum average information capacity <C>(max) as <C> maximized over the receiver spacing a and the optimal normalized receiver spacing (ka)(opt) as the spacing maximizing <C>. Both <C>(max)/n and (ka)(opt) scale as (S/N)(1/2) for S/N<(S/N)(c), while (ka)(opt)=mpi and <C>(max)/n approximately log(S/N) for S/N>(S/N)(c).

Absence of Anderson Localization of Light in a Random Ensemble of Point Scatterers

“…To demonstrate this, we repeated the calculations presented above for elastic waves which, in contrast to the electromagnetic case, can also have a propagating longitudinal component. The elastic Green's function exhibits the same 1/r ij divergence for r ij → 0 as the scalar one (3) and our calculations show clear signatures of Anderson localization transition, similar to the scalar case [37].…”

On the Diffusion of Electromagnetic Waves and Applicability of Diffusion Equation to Multipath Random Media

“…We will adopt (11) to evaluate the average intensity and use (12) to obtain the mean excess loss from our 2-D full wave simulations. For instance, if the radial component of the flux density vector is in the -direction, the mean excess loss is (13) These quantities are the true transport quantities, to which the transport theory will be compared.…”

“…Such characteristics like the mean pathloss can be used to assist wireless system design and determine the coverage range of a cellular base station in a metropolitan area or the required transmit power of a wireless network in a typical office environment [9]. The diffusive behavior of EM waves was also used to study the communication capacity in multipath media [10], [11].…”

Transmission matrix of a scattering medium and its applications in biophotonics

“…In recent years, the control of wave propagation in complex media has received a lot of attention, being crucial to improve information transfer in a wide range of domains, including imaging, medical therapies and telecommunication amongst others [1,2,3,4]. The fundamental problem of wave propagation in complex media is that the multiple scattering events result in a speckle as output wavefront that has lost any correlation with the input wavefront [5].…”