Agilent Mimo Channel Modeling and Emulation Test Challenges

Application Note This application note begins with a review of MIMO technologies and the basic properties of wireless channels and goes on to introduce the concepts of spatial correlation and its effects on MIMO performance. It also includes a demonstration of modeling the spatial characteristics of MIMO channels and describes how these complex channels can be emulated using commercially available instrumentation such as the Agilent N5106A PXB baseband generator and signal emulator. Multiple Input Multiple Output (MIMO) technology holds the promise of higher data rates with increased spectral efficiency. Due to the potential improvement in system performance and advances in digital signal processing, many wireless systems, including the IEEE 802.11n wireless LAN, IEEE 802.16e-based Mobile WiMAX™ Wave 2 and the Long-Term Evolution (LTE) mobile wireless system, have recently adopted the use of MIMO and multiple antenna technologies. All of these commercial wireless systems operate in high multipath environments and it is the benefit of multipath that provides the performance improvement when using multiple antenna configurations. While MIMO offers the potential for increased signal robustness and capacity improvement when operating in rich multipath environments, developing and testing MIMO components and systems requires advanced channel emulation tools that are easily configured and provide an accurate representation of realistic wireless channels and conditions. This application note begins with a review of MIMO technologies and the basic properties of wireless channels and goes on to introduce the concepts of spatial correlation and its effects on MIMO performance. It also includes a demonstration of modeling the spatial characteristics of MIMO channels and describes how these complex channels can be emulated using commercially available instrumentation such as the Agilent N5106A PXB baseband generator and signal emulator which will be referred to throughout the remainder of this document as the PXB.