1.1. Introduction

The Spatial Channel Model (SCM) [i] is used to evaluate multiple-antenna systems and algorithms. This model was developed within a combined 3GPP-3GPP2 ad-hoc group to address the need for a precise channel model definition that enables fair comparisons of various MIMO proposals.

The channel model was carefully designed to be consistent with field measurements, including the important narrow angle spread behavior observed in wide-band channels. The detailed model is described in [ii]. Later, the SCM was extended by a modification proposed in [iii] by The European Wireless World Initiative New Radio (WINNER) project to increase the bandwidth from 5 MHz up to 100 MHz. The modified model is called the Spatial Channel Model Extended (SCME) and is part of the WINNER models described in [iv].

The SCM and the SCME use a ray-based modeling technique wherein each path is modeled by a number of sub-paths as a sum-of-sinusoids, each representing individual plane waves received by the antenna array. The ray-based modeling technique is relatively simple to use and has advantages over other techniques because it automatically addresses many of the important aspects of the channel model by summing the sub-path sinusoids. These include spatial correlation between antenna elements and the autocorrelation resulting from the non-classical Doppler spectra. Both spatial correlation and autocorrelation are due to the effects of narrow angle spread, which is a function of angle.

The subject of this paper is Correlation-based Modeling; which is another approach used in spatial channel modeling. Recently, correlation-based spatial channel models have become popular because of their simple mathematical form and ease of modeling. Technical comparisons show that correlation and ray-based modeling are equivalent [v]. Correlation-based spatial channel modeling refers to the use of filtered complex Gaussian noise samples to obtain independent temporal fading sequences. These are spatially correlated with a correlation matrix. A complete Spatio-Temporal fading model is defined by this technique.