Metrics and Methods for Evaluation of Over-The-Air Performance of MIMO User Equipment

Commercial User Equipment (UE) testingand certification has become more complex for state-of-the-art mobile communication standards such as 3rdGeneration Partnership Project (3GPP) Long-Term Evolution(LTE) due to the extensive use of Multiple Input-Multiple Output (MIMO) transmission techniques. Thevariety of different MIMO operating modes and the almostunlimited choice of possible multipath channel conditionsunder which UE performance may be evaluated are notaccounted for by established Single Input-Single Output(SISO) Over-The-Air (OTA) performance metrics likeTotal Isotropic Sensitivity (TIS) and Total Radiated Power(TRP). As pointed out in this contribution, meaningfulmetrics and cost-effective, low-complexity measurementmethods can, nevertheless, be derived by focusing oncharacterization of the physical attributes of UE and byadopting statistical metrics. Starting from a brief review ofthe most important MIMO operating modes in the 3GPPLTE standard, the relation between UE properties and UEperformance, which is observed in these operating modes, isdiscussed. Two complementary metrics and correspondingmeasurement procedures for evaluation of MIMO OTAperformance are presented in order to address the diversityof possible propagation scenarios. Measurement resultsfrom preliminary implementations of the two proposedmeasurement procedures, including comparison betweendifferent LTE devices, are presented