18 - Spatial channel model

Summary

Specification of a propagation channel model is of foremost importance in the design of a wireless communication system. A propagation model is used to predict how the channel affects the transmitted signal so that transmitters and receivers that best compensate for the channel's corrupting behaviors can be developed. A propagation model is also used as a basis for performance evaluation and comparison of competing wireless technologies. An example of such propagation models is ITU-R channel models that were developed for IMT-2000 system evaluation. A wireless propagation channel model needs to be refined as new system parameters (e.g. larger bandwidths and new frequency bands) or radio technologies exploiting new characteristics of the channel such as multi-antenna schemes are introduced. A well-defined channel model allows for the assessing of the system performance under new parameters as well as gains due to introduction of new radio technologies. The performance of multi-antennas technologies, for example, depends upon the spatial correlations between antennas. As ITU-R channel models do not characterize the spatial correlations, using these propagation models may lead to overestimating the gains of multi-antenna techniques. In order to provide a reasonable propagation platform for multi-antenna techniques evaluation, the spatial channel model (SCM) was developed. The SCM defines a ray-based model derived from stochastic modeling of scatters and therefore allows to model spatial correlations required for evaluation of multi-antenna techniques.