Simplify Measurement Setups for 5G NR Signal Generation and Analysis
2020-04-09 | 7 min read
Whether you’re working in 5G NR component characterization, design verification, and pre-conformance, to volume production testing, you need to ensure your products that conform to the latest standard. Of course, firstly you need to understand the 3GPP technical specification and test requirements.
3GPP Technical Specification for 5G NR Test
The 3GPP specifies 5G NR test requirements for user equipment (UE) and base stations (gNB). Table 1 illustrates the technical specification (TS) for UE and gNB minimum test requirements and conformance tests. The conformance testing documents specify the measurement procedures. The testing method consists of conducted tests, radiated tests, or a hybrid for the various frequency ranges.
Each document specifies the transmitter characteristics, receiver characteristics, and performance test requirements. Additionally, Part 1 represents conducted tests, and Part 2 represents radiated tests. Part 3 is for NR UE interworking between FR1 and FR2, or NR and LTE.
Set up 5G NR standard-compliant test signals
To perform conformance tests, 3GPP identifies test signals for specific test cases. 3GPP defines the test models (TM) for 5G NR gNB transmitter test cases and the fixed reference channel (FRC) for receiver test cases in TS 38.141. The test models standardize the resource block allocations.
Each test signal has more than 500 adjustable parameters with relevant bandwidths and numerologies.
The physical channels set up for tests need to be based on the specification, including logical channels, resource allocation, payload data, bandwidth parts, control resource sets, cell-specific settings, and RF parameters. Each test signal has more than 500 adjustable parameters with relevant bandwidths and numerologies.
For example, TM3.3 is for the 5G NR TDD downlink transmitter test cases, frequency error, and EVM for QPSK modulation. Other than the test model, you also need to select the signal bandwidth (based on the Table 5.3.2-1 and 5.3.2-2 in TS 38.104), numerology (subcarrier spacing), duplex type (TDD or FDD). The downlink signal includes SS/PBCH, DCI, DL-SCH, CSI-RS, and LTE coexistence info. Figure 1 shows the channel setup for the Downlink Shared Channel (DL-SCH). Each DL-SCH channel has about 50 parameters (in the center box).
Graphical display (at the bottom) for the entire Radio Frame is located. The x-axis represents the slot based on current numerology and the y-axis represents the resource block (RB) value. The colors represent the different channel types used in the frame – green represents a downlink shared channel (DL-SCH) and the light green represents downlink control information (DCI). The detailed RB mapping appears at the bottom-right corner, including the demodulation reference signal (DMRS) in red, and the physical downlink shared channel (PDSCH) in green. The setups are not a fun job to configure all the parameters for all logical channels.
Unless you are familiar with the standardization process, it is rather difficult to understand how the parameters work by just reading through the specifications.
Accelerate Test Setups with Pre-Configured Setups
Luckily, Keysight provides pre-configured setups for channel resource allocation in the waveform creation software tool. You just need to select the test model for the specific test case and choose the carrier bandwidths, numerologies, and duplex types. The pre-configured setups help you generate 3GPP 5G NR standard-compliant signals for testing gNB, UE transmitters, and receivers quickly and easily as shown in Figure 2.
Similarly, Keysight also provides pre-configured setups for signal analysis. Figure 3 shows that the measurement application supporting defined, standard-based conformance test setups can save time and give you confidence that your measurements comply with standards.
Configure measurement setup for 5G NR components test
Stimulus-response measurements provide a straightforward method for evaluating the performance of RF components. They require a stimulus input test signal and acquisition of the output signal for further analysis. Figure 4 shows a signal generator (bottom) and a signal analyzer (top) setup for stimulus-response measurements.
To configure 5G NR test signals on the signal generator, you can use waveform-creation tools such as Keysight PathWave Signal Generation for 5G NR. You can save the configuration as a PathWave 89600 VSA setup file, simplifying VSA configuration to quickly demodulate the signal without configuring the demodulation parameters on a signal analyzer. Keysight’s new M9384B VXG signal generator allows you to automatically set up the X-Series signal analyzer to measure the desired signal from the signal generator by pressing a single button.
Generating and analyzing a variety of standard-compliant 5G NR test signals requires a flexible waveform creation software and measurement applications. The software tools allow you to quickly and easily creating and analyzing custom 5G waveforms based on pre-configured, standard-based test signals.
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