As companies rush to get Long Term Evolution (LTE) products to market, engineers face tough challenges in testing these often complex devices. The mandate to include Multiple-Input Multiple-Output (MIMO) means many engineers are working to optimize their multi-antenna architectures. To achieve time-to-market goals, the MIMO solutions under development need to work correctly in real-world situations. Defining situations when MIMO transmissions will improve system performance can be complicated, but it is a critical aspect of successful implementation. Of particular interest is how to quickly determine whether a MIMO channel is capable of supporting spatial multiplexing under a given signal-to-noise ratio (SNR). Fortunately with the proper test equipment, a figure of merit called “condition number” can provide a short-term indication of the SNR required to properly recover a MIMO transmission over the selected wireless channel. This application note will review the basic concepts of MIMO with specific application to spatial multiplexing in 3rd Generation Partnership Project (3GPP) LTE. It will show measurements of channel coefficients and associated condition numbers as they relate to the SNR at the LTE receiver. How antenna and channel correlation affects system performance will also be discussed, along with recommendations for the best measurement tools to use when developing LTE products and systems. Introduction