About Error Summary Data (802.16 OFDMA)

Menu Path: Trace > Data >Demod > Syms/Errs

This topic provides additional measurement and analysis information unique to Error Summary trace data and IEEE Institute of Electrical and Electronics Engineers. A US-based membership organisation that includes engineers, scientists, and students in electronics and related fields. The IEEE developed the 802 series wired and wireless LAN standards. Visit the IEEE at http://www.ieee.org 802.16 OFDMA modulation analysis. The Error Summary results are shown in the upper section of the Syms/Errs trace display. This topic contains the following measurement, analysis, and programming information:

When making measurements of DL Down Link (forward link: from base station to cell phone)-PUSC partial usage of subchannels: Some of the subchannels are allocated to the transmitter. data bursts that occupy fewer slots than allocated, the allocated-but-unoccupied slots will be used when computing error metrics (like DataRCE). Therefore, if many slot are unoccupied, but allocated, these metrics may include significant error power which is not present on data carrying subcarriers. This occurs automatically when an analyzed DL-PUSC data burst is detected as having allocated-but-unoccupied slots (relative to the decoded DL-MAP downlink map: A MAC message that defines burst start time for both time division multiplex and time division multiple access (TDMA) by a subscriber station (SS) on the downlink. or the user-provided zone definition).

Averaging and Error Summary Data

When averaging is on, averaging is applied to the numeric error data in the symbol/errors table, see Averaging with Digital Demodulation. Error data from the current scan is not included in the average if any of these conditions exist:

For more information, see Troubleshooting and Trace Indicators help.

Using Band Power markers to limit Error Information

For RCE Relative Constellation Error is the RMS level of the Error Vector Magnitude, averaged over all subcarriers and all detected OFDM symbols. (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.) error information for all points over a selected region, use the band-power markers with the Error Vector Spectrum and Error Vector Time trace data. The Error Vector Spectrum trace data will compute the RCE (EVM) for all symbols within a specified subcarrier region and Error Vector Time trace data will compute the RCE (EVM) for all subcarriers within a specified symbol-time region.

For example, here's how the symbol RCE (EVM) for 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. subcarriers 11, 12, and 13 could be computed. Click Trace > Data > Demod > Error Vector Spectrum to display the Error Vector Spectrum trace data; then click Markers > Calculation and select the Band Power check box to turn on the band-power markers.

Now position the band-power markers to select the region of interest; place the markers so that they are exactly on or close to the specific subcarriers of interest. Center the marker at subcarrier 12, enter 12 in the Center text box and set the width to two carriers, enter 2 in the Width text box. This encloses the region of interest (subcarriers 11, 12, and 13). Then set Calculate: to Rms to display the RCE (EVM) in %rms, this is the RCE (EVM) (%rms) for all symbols within subcarriers 11, 12, and 13.

The same procedure can be used with the Error Vector Time trace data display to find the RCE (EVM) (%rms) for all subcarriers within a specific range of symbol-times.

Querying summary table data results programmatically

To programmatically query the Trace Summary Table data results using the Summary() and SummaryUnit() methods in the MeasurementData object.

See the How To Query Summary Table Data Results topic for more information.

See Also

About the Symbol Table (802.16 OFDMA)

Available Error Summary Data (802.16 OFDMA)

Syms/Errs (802.16 OFDMA)