On a 3GPP ray-based spatial channel model for MIMO system emulation: Implementation and evaluation.

摘要

The mitigation of random effects in a wireless communication channel is a problem considered for many years. In the present day context, given the ever increasing need for, and growth of, bandwidth intensive applications like streaming wireless HD video on fast moving user equipment (UEs, i.e., user communication devices), this issue has intensified from being a theoretical pursuit to a must-be-solved practical endeavor. In that regard, the ability to accurately model the outdoor (or indoor) propagation conditions in a laboratory setting becomes vital to validating state-of-the-art wireless standards and the devices that derive from them. Laboratory-based analysis is a significant catalyst in reducing the time-to-market for telecom equipment manufacturers. Modeling a wireless channel has been a topic under quite a bit of study. This has progressed from the Jakes model developed for single antenna systems to the correlation and ray-based models used for multiple antenna systems. The models prescribed by the 3rd Generation Partnership Project (3GPP) in its standards, like the ray-based model, aim to realistically reproduce channel environments in software and hardware, by incorporating all the variables that characterize any particular fading scenario.;In this thesis, the technical report produced by 3GPP detailing the Spatial Channel Modeling (SCM) for multiple input multiple output (MIMO) simulations is followed closely as a basis for developing a real-time channel emulator on a National Instruments (NI) based Real Time (RT) Platform. First, a general purpose channel emulator is described in terms of its structure and functionality and currently known channel models are briefly investigated. Next, the spatial channel model in the standard is described in detail along with the reasons for choosing to use it in the thesis. All the parameters involved are defined, and the formula for constructing the channel is carefully investigated. Next, the channel emulator built on the National Instruments LabVIEW platform is described along with both the changes and modifications made to the design parameters so as to adapt it to the operating constraints of the RT platform. The spatial and temporal characteristics of the model are also described and plotted. Finally, the model is tested for reliability by methodically changing the various channel parameters and observing their effects on an Orthogonal Frequency Division Multiplexing (OFDM) test vector by generating BER performance plots in MATLAB. Diversity schemes are also employed to improve rate performance.