E-UTRA Test Model

Description

E-UTRA Test Models (E-TMs) are a suite of predefined downlink physical layer signal configurations specified in 3GPP TS 36.141 (Base Station testing) and TS 36.143 (UE testing). They are not used in commercial network operation but are critical tools for laboratory testing, type approval, and conformance certification. An E-TM defines a specific combination of physical channels and signals to create a deterministic test waveform. This typically includes specific allocations for the Physical Downlink Shared Channel (PDSCH) with a defined modulation (e.g., QPSK, 16QAM, 64QAM, 256QAM), coding rate, and resource block allocation. It also includes standard Cell-Specific Reference Signals (CRS), synchronization signals (PSS/SSS), and control channels (PDCCH/EPDCCH) configured in a known way. The models are designed to stress specific aspects of the device under test. For example, E-TM1.1 might define a full resource block allocation with QPSK to test maximum power, while E-TM3.1 might define a 64QAM signal at a high power level to test transmitter EVM and spectral emissions. For receiver testing, a base station tester generates the precise E-TM waveform, and the UE's performance metrics like throughput, block error rate (BLER), or sensitivity are measured against the expected values. The models cover various bandwidths, transmission modes (e.g., TM2, TM3), and scenarios to ensure comprehensive testing of RF parameters such as output power, power control, transmitted signal quality, unwanted emissions, and receiver sensitivity.

Purpose & Motivation

E-UTRA Test Models were created to provide a unified, unambiguous, and reproducible methodology for testing LTE equipment against the stringent RF performance requirements set by 3GPP. Before standardization, manufacturers and test houses could use proprietary test signals, leading to inconsistent results and difficulties in certifying device compliance. The E-TMs solve this by providing a common reference. Their purpose is threefold: First, to enable consistent and fair conformance testing for regulatory approval (e.g., GCF, PTCRB). Second, to provide a reliable benchmark for R&D and verification testing during product development, allowing engineers to isolate and measure specific RF impairments. Third, to define the absolute limits of performance (e.g., the maximum allowed Error Vector Magnitude or adjacent channel leakage power) that a commercial product must not exceed. They address the complexity of LTE's flexible OFDMA resource grid by providing specific, fully-defined instantiations of that grid for test purposes. This ensures that all parties—chipset vendors, device manufacturers, network operators, and certification bodies—are testing against the exact same stimulus, guaranteeing interoperability and network performance.