With the emergence of Long Term Evolution (LTE) wireless devices, the demand for testing Multiple-Input Multiple-Output (MIMO) performance is increasingly critical. MIMO performance testing challenges the traditional antenna test technique commonly used today. As a result, the major wireless standards development organizations, such as CTIA, are addressing new test methods to evaluate MIMO performance. This paper analyzes the influence of the antenna pattern under different MIMO channels and shows the numeral simulations. Chamber based test results for the performance evaluation of LTE devices will also be shown.