LTE Modulation Measurements

This measurement displays the Power vs. RB grid with the RB Color Map, the measurement table and measurement progress bar.

Two Dimensional Power vs RB Grid

Shows the PDSCH power of each RB using color. The y‑axis is frequency (sub‑carriers) and the x‑axis is time (sub‑frame). There are ten columns for the ten sub‑frames. The number of subcarriers varies depending on the bandwidth chosen and hence the number of RBs on the y‑axis. Each cell in the grid corresponds to a particular RB in a particular sub‑frame. As the measurement progresses, each sub‑frame is measured and the cells in the grid are colored according to the PDSCH power in the RB.

Resource Block Color Map

The color mapping of the RB power level is determined by the RB Color Map Max Value and RB Color Map Range submenus. Setting these values can be done by entering them manually or by pressing Autoscale Color Map.

Note	The Power Offset is applied to the measured value before matching to a color map.

Active RBs
The number of active Resource Blocks. A RB is determined to be active if the measured PDSCH power is above a certain threshold that indicates that the RB is being used for carrying data.

Utilization
The percentage of RBs that carry data. It is the number of Active RBs divided by the total number of RBs, expressed as a %.

EVM
The RMS (%) of all of the error vectors between the reconstructed ideal signals and the
received signals, divided by the RMS value of the ideal signals. Individual frame EVM(RMS) is displayed for the modulation types QPSK, 16-QAM, and 64-QAM.

Measurement Progress Bar

This progress bar indicates the sub‑frame that is currently being measured.

Markers are available for use in the Power vs Resource Block measurement. The markers will outline the selected RB. Above the two dimensional grid, the specific RB subcarrier/sub‑frame coordinates will be displayed along with its power level.

This measurement displays the constellation of the demodulated symbols over the first sub‑frame and a results table of the following measurements.

Ref Signal (RS) Power

Reference Signal power displayed in dBm or Watts. The reference signal is used for downlink channel estimation.

The RMS (%) of all the error vectors, between the reconstructed ideal signals and the
received signals, divided by the RMS value of the ideal signals. When EVM Max Hold is On (Setup menu) two values are displayed. The first number is the maximum EVM (rms) value since Reset and the second number is the current measured value. Reset occurs when setup parameters are changed or by toggling the EVM Max Hold button.

The difference between the measured carrier frequency and the specified carrier frequency is the frequency error. This number is only as accurate as the frequency reference that is used, and is typically only useful with a good external frequency reference or GPS.

Carrier Frequency is the measured transmitter operating center frequency.

Sync Signal (SS) Power

Sync signal power displayed in dBm or Watts.

The peak (%) of all the error vectors, between the reconstructed ideal signals and the received signals, divided by the RMS value of the ideal signals. When EVM Max Hold is On (Setup menu) two values are displayed. The first number is the maximum EVM value since Reset and the second number is the current measured value.

Freq Error displayed in parts per million (ppm).

Cell identifying information sent by the transmitter in the sync signal.

This measurement shows the power levels of key physical layer Control Channels and also includes the numerical results table described in the Constellation section above.

Ref Signal (RS) Power

Reference Signal power displayed in dBm. The reference signal is used for downlink channel estimation.

Primary Sync Signal power displayed in dBm or Watts. The primary sync signal is used to obtain slot synchronization. It contains information needed for cell search.

Secondary Sync Signal power displayed in dBm or Watts. The secondary sync signal is used to obtain frame synchronization and cell identity. It contains information needed for cell search.

Physical Broadcast Channel Power. This physical channel carries system information for user equipment (UE) requiring access to the network.

Physical Control Format Indicator Channel Power. This channel provides information to enable the UE to decode the PDCCH and PDSCH channels.

Physical Hybrid Automatic Repeat Request Indicator Channel. Transmits the channel coded HARQ indicator codeword used for error correction.

Physical Downlink Control Channel.

Ng is a parameter that determines the number of PHICH (Physical Hybrid ARQ Indicator Channel) groups in a LTE sub-frame (this number is constant for all sub-frames).

Measures the delay between the signals from two antennas at the antenna ports.

Modulation Summary displays the Ref Signal (RS) Power, Sync Signal (SS) Power, EVM (rms), Freq Error (Hz and ppm), Cell ID and PBCH Power in a table format. Refer to individual modulation measurement descriptions for additional detail on each measurement.

3. Press the Power vs Resource Block submenu key to activate the Power vs Resource Block measurement view.

4. Press the Power vs Resource Block submenu key again to list the Power versus RB menu for setting up the RB Color Map maximum value and range. Press a submenu key to change the desired parameter. Or, press the Autoscale Color Map submenu key to automatically set the Max and Range values.

1. While in the Power vs Resource Block measurement, press the Marker main menu key. The RB Marker submenu opens. The Marker State button default value is On, so the markers highlight a row of sub‑frames and a column of sub‑carriers.

3. To choose a specific resource block, press the Marker RB # submenu key and move it to the desired RB # using the arrow buttons, knob or enter a RB number and press Enter.

4. To choose a specific sub‑frame, press the Marker Sub‑frame submenu key and move it to the desired Sub‑frame using the arrow buttons, knob, or enter the sub‑frame number and press Enter.

3. Press the Constellation submenu key to activate the Constellation measurement view (Figure: Constellation Measurement View). Press the Constellation submenu key again to list the Constellation menu to setup the reference points and data legend.

a. Press the Reference Points submenu key to turn the reference points (small white circles) On or Off.

3. Press the Control Channel Power submenu key to activate the Control Channel Power display (Figure: Control Channel Power). Press the key again to view or change the Display Mode and Control Channel EVM settings.

3. Press the Tx Time Alignment submenu key to set the modulation measurement to Tx Time Alignment view (Figure: Tx Time Alignment).

3. Press the Modulation Summary submenu key to activate and display the modulation measurements in table format (Figure: Modulation Summary).


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