Error Vector Spectrum (5G NR/5G-Advanced)

There are two types of traces in the Trace > Data > Demod and MIMO Multiple Input, Multiple Output: A physical layer (PHY) configuration in which both transmitter and receiver use multiple antennas. menus that display component carrier data: CCn (component carrier is fixed), and Selected Display CC (component carrier is dynamically selected using the Display parameter). See About Per-Carrier Trace Types for more information.

The 5G NR/5G-Advanced Error Vector Spectrum trace shows the OFDM Orthogonal Frequency Division Multiplexing: OFDM employs multiple overlapping radio frequency carriers, each operating at a carefully chosen frequency that is Orthogonal to the others, to produce a transmission scheme that supports higher bit rates due to parallel channel operation. OFDM is an alternative tranmission scheme to DSSS and FHSS. symbol and subcarrier Error Vector Magnitude (EVM Error vector magnitude (EVM): A quality metric in digital communication systems. See the EVM metric in the Error Summary Table topic in each demodulator for more information on how EVM is calculated for that modulation format.) vs. subcarrier (frequency) and Symbol (time) for the component carrier. There is separate trace for each measurement channel. The Error Vector Spectrum trace allows you to easily attain information about the signal modulation quality as a function of the subcarriers.

When more than one carrier is defined in the Aggregation Table, "(CCn)" will appear in the title of this trace, where "n" is the number of the component carrier whose data is displayed in the trace. Select the desired component carrier number using the Configuration > Carriers > Display parameter.

Error Vector Spectrum trace provides the following data results: the subcarrier EVM and the RMS average subcarrier EVM. Unused subcarriers are blanked and not included in the measurement analysis. There is also a plot (default White line) of the RMS average subcarrier EVM for all subcarriers and symbols in the measurement analysis.

For 5G NR measurements, the OFDM Meas , OFDM Ref, Error Vector Spectrum, Error Vector Time and Detected Allocations Time traces contain data for all layers (MIMO PUSCH measurements) and subsegments (DLBWP, SSBlock) on a single trace, which offers the benefit of viewing IQ data for a single layer/subsegment or a composite of some or all layers/subsegments. You can use the Trace > Digital Demod > Filtered SubSegments feature to show or hide layers as needed. Markers are supported for each layer. To add a marker to a particular layer, simply hide all layers except for the desired layer before adding the marker.

Filtered SubSegments only appears in the Trace > Digital Demod tab when multiple layers or subsegments are detected by the selected trace.

5G NR demodulation also supports filtering by physical channel type for traces that contain physical channel data. You can use the Trace > Digital Demod > Filtered Channel Types feature to show or hide data by physical channel type as needed.

Filtered Channel Types only appears in the Trace > Digital Demod tab when physical channel data is detected by the selected trace.

See About Mixed Numerologies for information about multiple/mixed numerologies.

A marker placed on a symbol point that reads as shown below:

indicates that the marker is

on subcarrier -505
in the PDSCH Physical Downlink Shared Channel channel
with a QAM256 modulation type
on symbol 120
the EVM value at this point is ~0.88%, and the average error over all the resource elements on this subcarrier is ~.57 %

You can limit the number of symbols included in the measurement analysis data results using the Result Length, Meas Interval, and Meas Offset parameters.

Trace Color coding Scheme

A multi-color coding scheme is used to make it easy to visually identify common symbols, subcarriers, and data results within various OFDM Traces. This makes cross trace data comparisons and analysis easier to accomplish. Different colors are assigned to symbols representing elements including: PSS/SSS/PBCH/PBCH_DMRS/PDSCH/PDSCH_DMRS/PUSCH/PUSCH_DMRS/PUCCH/PUCCH_DMRS. Some common color scheme Traces include: Error Vector Spectrum, Error Vector Time, OFDM Meas, Frame Summary and Slot Summary trace data.

The 5G NR color scheme has been simplified to help make visual sense of a complex standard. The default color assignment for 5G NR follows these general guidelines:

DMRS and PTRS signals
- PTRS and DMRS signals generally are generally assigned cooler colors (greens, blues).
- All DMRS signals share a common color. You can distinguish between DMRS signals using markers, but each DMRS is also visually distinguished by the physical channel in which it is located.
- All PTRS signals share a common color. You can distinguish between PTRS signals using markers, but each PTRS is also visually distinguished by the physical channel in which it is located.
Physical channels (PDCCH, PDSCH, PUCCH, PUSCH, etc.)
- Physical channels are generally assigned warmer colors (yellows, oranges, reds)
- Each physical channel type has an assigned group of colors. For channel collections (multiple channels of the same type), the display will rotate through a group of three similar but distinct colors to distinguish between each channel in the collection. For example, if a signal contains 6 PDSCHs (PDSCH0-5), PDSCH0, PDSCH1 and PDSCH2 will each have similar but uniquely different color assignments. The same colors will be repeated for PDSCH3, PDSCH4 and PDSCH5.

You can also customize and re-assign Trace colors schemes, see the Display Preferences Color tab (click Utilities > Display Preferences > Color tab and select a new color for the active Mod Type element).