The well-known results of the spatial correlation function for two-dimensional and three-dimensional diffuse fields of narrowband signals are generalized to the case of general distributions of scatterers. A method is presented that allows closed-form expressions for the correlation function to be obtained for arbitrary scattering distribution functions. These closed-form expressions are derived for a variety of commonly used scattering distribution functions.

In this paper we investigate the capacity behavior of spatial constrained multiple-antenna array communications. By increasing the number of antennas within a fixed region of space the antenna array becomes dense and spatial correlation inhibits capacity growth. Using a novel spatial channel model we show that the underlying physics of wave propagation limits the capacity of constrained arrays. A theoretically derived antenna saturation point is shown to exist for dense array MIMO systems, at which there is no capacity growth with increasing antenna numbers. We show this saturation point increases linearly with the radius of the region, and that it naturally lends itself to a definition for the theoretical maximum capacity for a fixed region of space.

The large spectral efficiencies promised for multiple-input multiple-output (MIMO) wireless fading channels are derived under certain conditions which do not fully take into account the spatial aspects of the channel. Spatial correlation, due to limited angular spread or insufficient antenna spacing, significantly reduces the performance of MIMO systems. In this paper we explore the effects of spatially selective channels on the capacity of MIMO systems via a new capacity expression which is more general and realistic than previous expressions. By including spatial information we derive a closed-form expression for ergodic capacity which uses the physics of signal propagation combined with the statistics of the scattering environment. This expression gives the capacity of a MIMO system in terms of antenna placement and scattering environment and leads to valuable insights into the factors determining capacity for a wide range of scattering models.

In this paper we derive a new upper bound for the pairwise error probability of space-time codes in a quasi-static Rayleigh fading channel, considering antenna configuration at the transmitter side. The design criterion for existing spacetime trellis codes is based on the rank and the determinant of the distance matrix between two code words. In particular, the diversity advantage of the space-time code is associated to the rank of the distance matrix. We show that when the transmit antenna region is small, the diversity advantage given by the space-time code is reduced by the transmit antenna configuration and the diversity advantage of the code depends on the rank of the antenna configuration matrix. We also show that the uniform linear array antenna configuration diminishes the diversity advantage provide by the space-time code while the uniform circular array antenna configuration does not effect to the diversity advantage of the space-time code.

In this paper, we derive analytical expressions for the exact pairwise error probability (PEP) of a space-time coded system operating over spatially correlated fast (constant over the duration of a symbol) and slow (constant over the length of a code word) fading channels using a momentgenerating function-based approach. We discuss two analytical techniques that can be used to evaluate the exact-PEPs (and therefore approximate the average bit error probability (BEP)) in closed form. These analytical expressions are more realistic than previously published PEP expressions as they fully account for antenna spacing, antenna geometries (Uniform Linear Array, Uniform Grid Array, Uniform Circular Array, etc.) and scattering models (Uniform, Gaussian, Laplacian, Von-mises, etc). Inclusion of spatial information in these expressions provides valuable insights into the physical factors determining the performance of a space-time code. Using these new PEP expressions, we investigate the effect of antenna spacing, antenna geometries and azimuth power This work was supported by the Australian Research Council Discovery Grant DP0343804.

In this paper, we derive an analytical expression for the exact pairwise error probability (PEP) of a differential space-time coded system operating over a spatially correlated slow fading channel. An analytic model for spatial correlation is used which fully accounts for antenna spacing, antenna geometry and non-isotropic scattering distributions. Inclusion of spatial information in error performance analysis provides valuable insights into the physical factors determining the performance of a differential space-time code (DSTC). Using this new PEP expression, we investigate the effects of antenna spacing, antenna geometries and azimuth power distribution parameters (angle of arrival/departure and angular spread) on the performance of a differential space-time block code (DSTBC) proposed in the literature for two transmit antennas.

In this paper we present a new upper bound on the capacity of MIMO systems. By characterizing the fundamental communication modes of a physical aperture, we develop an intrinsic capacity which is independent of antenna array geometries and array signal processing. Using a modal expansion for free-space wave propagation we show that there exists a maximum achievable capacity for communication between spatial regions of space, which depends on the size of the regions and the statistics of the scattering environment.

This paper investigates the spatial-frequency channel characterization of Ultra-wideband (UWB) wireless communication systems. Firstly, a novel frequency dependent UWB channel model is constructed based on the theory of electromagnetic diffraction mechanism, which causes the field strength to vary with the frequency in each multipath. Secondly, we build a space-frequency model, which includes spatial characteristics such as angular power spectrum, and physical sampling points in space. The space-frequency model has two special cases (i) discrete multipath model, and (ii) cluster model, which can be readily used to generate channel data for any arbitrary set of sensor locations. The reconstruction results from channel measurements show the accurateness of the novel frequency dependent model, with reconstruction error decreasing by 40%, compared to the traditional Turin model.