Commercial User Equipment (UE) testing and certification has become more complex for state-of-the-art mobile communication standards such as 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) due to the extensive use of Multiple Input-Multiple Output (MIMO) transmission techniques. The variety of different MIMO operating modes and the almost unlimited choice of possible multipath channel conditions under which UE performance may be evaluated are not accounted for by established Single Input-Single Output (SISO) Over-The-Air (OTA) performance metrics like Total Isotropic Sensitivity (TIS) and Total Radiated Power (TRP). As pointed out in this contribution, meaningful metrics and cost-effective, low-complexity measurement methods can, nevertheless, be derived by focusing on characterization of the physical attributes of UE and by adopting statistical metrics. Starting from a brief review of the most important MIMO operating modes in the 3GPP LTE standard, the relation between UE properties and UE performance, which is observed in these operating modes, is discussed. Two complementary metrics and corresponding measurement procedures for evaluation of MIMO OTA performance are presented in order to address the diversity of possible propagation scenarios. Measurement results from preliminary implementations of the two proposed measurement procedures, including comparison between different LTE devices, are presented.
Abstract-In this document a numerical validation of the decomposition method is presented. This is a powerful method to split MIMO (multiple input multiple output) enabled UE (user equipment) tests in a radiated and a conducted part to save measurement time.The concept and fundamental properties of this procedure are introduced. The aim is to show the validity under certain circumstances of this concept by simulation.The chosen path is to employ a 2×2 MIMO transmission system. Stochastic and deterministic channel models are used, as Rayleigh channels with no line of sight components (NLOS) and identity matrices. Receiving antenna setups with different characteristics were investigated.Also the practical behaviour of the method using CTIA (The Wireless Association) LTE (Long Term Evolution) reference antennas has been examined. Therefore the distributions of the antenna condition number and of the deviation between the results are provided.Index Terms-Decomposition method, decomposition approach, LTE, LTE device test, MIMO, MIMO OTA test, OTA, two-channel method.
Over-the-air (OTA) throughput tests of wireless Multiple-Input Multiple-Output (MIMO) devices are an important tool for network operators and manufacturers. The user equipment (UE) is placed in an anechoic chamber and a random fading process is emulated by a base-station emulator (BSE). The antenna characteristic of the UE is taken into account by sampling the sphere around the UE with the BSE test antenna at a large number of positions. For low-variance throughput results, long measurement intervals over many fading realizations are required, leading to long and expensive measurement periods in an anechoic chamber. To speed up the OTA test, we analyze the Decomposition Method (DM). The DM splits the throughput measurement into two parts: (1) a receiver algorithm performance tests taking the fading process into account and (2) an antenna performance test without fading process emulation. Both results are combined into a single throughput estimate. The DM allows for a measurement time reduction of more than one order of magnitude. We provide an analytic and numerical analysis as well as measurements. Our detailed results show the validity of the DM in all practical settings.
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