Frame Summary (802.16 OFDMA)
The trace is a summary table of 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 signal quality metrics. This summary data performs a "quick-check" of signal quality, including mean/peak/standard deviation values for many metrics required by conformance testing. These include 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. and RCE Relative Constellation Error is the RMS level of the Error Vector Magnitude, averaged over all subcarriers and all detected OFDM symbols. quality metrics (RMS, Data, Pilot, and Unmod); frequency offset metrics (Frequency Offset and Symbol Clock Offset); and preamble metrics (RSSI Received signal strength indication, Preamble RCE, and Preamble PCINR Reuse-1 and Reuse-3).
The results only apply to averaged measurements. Summary results include "Mean", "PeakHold", and Standard Deviation "StdDev" values for each metric. To make an averaged measurement you must specify the Average Type and number of averages "Count". To start and averaged measurement, open the Average tab of the MeasSetup properties dialog box and specify the Average Type and Count parameters (). Any will produce the same behavior for the trace results, but will affect the results on other traces depending on the actual Average Type selected.
The statistical data results will be filled with *** placeholders when average is off.
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is the computed Mean, Peak Hold, and StdDev results for the EVM (Syms/Errs trace) values for the measurement: is the mean EVM value for the measurement in dB and as the rms percentage (%rms). PeakHold is the peak EVM value for the measurementin dB and as the rms percentage (%rms). StdDev is the computed standard deviation of the RCE (EVM) values for the measurement in dB and as the rms percentage (%rms). |
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is the computed Mean, Peak Hold, and StdDev results for theDataRCE (Syms/Errs trace) values for the measurement: is the mean DataRCE value for the measurement (Data Tones only) in dB and as the rms percentage (%rms). PeakHold is the peak DataRCE value for the measurementin dB and as a rms percentage (%rms). StdDev is the computed standard deviation of the DataRCE values for the measurement in dB and as a percentage (%rms). |
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is the computed Mean, Peak Hold, and StdDev results for the Pilot RCE(Syms/Errs trace) values for the measurement: is the mean Pilot RCE value for the measurement (Pilot Tones only) in dB and as the rms percentage (%rms). PeakHold is the peak Pilot RCE value for the measurementin dB and as a rms percentage (%rms). StdDev is the computed standard deviation of the Pilot RCE values for the measurement in dB and as a percentage (%rms). |
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UnmodRCE(EVM)is the computed Mean, Peak Hold, and StdDev results for the UnmodRCE (Syms/Errs trace) values for the measurement: is the mean UnmodRCE value for the measurement. PeakHold is the peak UnmodRCE value for the measurement. StdDev is the computed standard deviation of the UnmodRCE values for the measurement. |
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(Frequency Error) is the computed Mean, Peak Hold, and StdDev results for the Frequency Error (Syms/Errs trace) values for the measurement: is the mean Frequency Error value for the measurement in Hz. PeakHold is the peak Frequency Error value for the measurementin Hz. StdDev is the computed standard deviation of the Frequency Error values for the measurement in Hz. |
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is the is the computed Mean, Peak Hold, and StdDev results for the Symbol Clock Error (Syms/Errs trace) values for the measurement: is the mean Symbol Clock Error value for the measurement in ppm. PeakHold is the peak Symbol Clock Error value for the measurementin ppm. StdDev is the computed standard deviation of the Symbol Clock Error values for the measurement in ppm. |
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Pmbl Power (RSSI) is the computed Mean, Peak Hold, and StdDev results for the RSSI (Syms/Errs trace) values for the measurement. Pmbl Power (RSSI) "Received Signal Strength Indicator" is a measurement of the total received power of the frame preamble associated with the active segment: is the mean RSSI value for the measurement in dBm deciBels referenced to a milliWatt: dB relative to 1 milliwatt dissipated in the nominal input impedance of the analyzer. PeakHold is the peak RSSI value for the measurementin dBm. StdDev is the computed standard deviation of the RSSI values for the measurement in dBm. |
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is the computed Mean, Peak Hold, and StdDev results for the preamble EVM values for the measurement: is the mean value for the measurement (Data Tones only) in dB and as the rms percentage (%rms). PeakHold is the peak value for the measurement in dB and as a rms percentage (%rms). StdDevis the computed standard deviation of the values for the measurement in dB and as a percentage (%rms). |
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is the computed Mean, Peak Hold, and StdDev values for the preamble CINR reuse 1 measurement measurement. is calculated as described in IEEE 802.16e-2005 8.4.11.3. Specifically this includes measuring the ideal power level of the active tones of the unequalized preamble, and dividing by the sum of the error power of the active tones and the total power of the inactive preamble tones. The standard describes differentiating noise power from interference power and scaling the error terms to approximate unboosted data. However, in testing it is not possible to differentiate between noise and interference, so the assumption is that all error components are contributed from interference, and therefore scaling of the numerator and denominator cancel out. This assumption is valid for transmitter testing situations where the noise floor is very low relative to signal and interference power. is the mean Pmbl PCINR R1 value for the measurement in dB. is the peak Pmbl PCINR R1 value for the measurement in dB. is the computed standard deviation of the Pmbl PCINR R1 values for the measurement in dB. |
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is the computed Mean, Peak Hold, and StdDev values for the preamble CINR reuse 3 measurement results for the measurement. is calculated as described in IEEE 802.16e-2005 8.4.11.3. Specifically this includes measuring the ideal power level of the active tones of the unequalized preamble, and dividing by the sum of the error power of the active preamble tones. This is similar to the Preamble RCE, except the equalizer is not applied prior to the RCE computation. The standard describes differentiating noise power from interference power and scaling the error terms to approximate unboosted data. However, in testing it is not possible to differentiate between noise and interference, so the assumption is that all error components are contributed from interference, and therefore scaling of the numerator and denominator cancel out. This assumption is valid for transmitter testing situations where the noise floor is very low relative to signal and interference power. is the mean Pmbl PCINR R3 value for the measurement in dB. is the peak Pmbl PCINR R3 value for the measurement in dB. is the computed standard deviation of the Pmbl PCINR R3 values for the measurement in dB. |
Standard Deviation Computations
Standard deviation (StdDev) is computed using exponentially weighted computations of mean and the expectation-squared metric, as described in IEEE 802.16e-2005 clauses 8.4.11.2 and 8.4.11.3. The computation is exactly as defined in the standard for RSSI and CINR metrics, but is modified slightly for RCE metrics. Specifically, the linear value of %rms is computed for RCE metrics, and this value is converted to decibels relative to the mean value, providing a standard deviation range in dB around the mean value. This difference in definition is annotated by the "+/-" prefix before the RCE StdDev metrics using dB units.
These equations describe the accumulation functions used for the results:
Mean[n] = { x[n]; n = 1
{ (1 - α) × Mean[n-1] + α × x[n]; n > 1
n = Measurement counter, n=1 is the first measurement.
α = { 1 / n; n < Average Count
{ 1 / (Average Count); n >= Average Count
x_2[n] = { |x[n]|^2; n = 1
{ (1 - α) × x_2[n-1] + α × (|x[n]|^2); n > 1
StdDev[n] = |x_2[n] – Mean[n]^2|
For RSSI & PCINR:
StdDev_dB[n] = 5*Log(StdDev[n])
For RCE:
StdDev_dB[n] = 20*Log(StdDev[n] / Mean[n] + 1.0)
Additional signal qualty metrics
For additional EVM and RCE metrics see the following summary tables:
Data Burst Info Table
Available Summary Data Table
See Also
Available Trace Data (802.16 OFDMA)
