NR Power Vs Time
- Updated2025-04-07
- 6 minute(s) read
NR Power Vs Time Overview
The NR Power Vs Time (PVT) measurement measures the time domain power dynamics of an NR signal. This measurement is also known as Transmit ON-OFF Time Mask measurement. The 3GPP specification defines limits for the signal power for signal OFF periods. The higher OFF power increases the rise over thermal noise (ROT) and causes interference to other users.
Measurement Overview Uplink PVT
The average OFF power for frequency range 1 and frequency range 2 shall not exceed the limits specified in 3GPP TS 38.521-1 specification and 3GPP TS 38.521-2 specification, respectively.
The table below shows UE OFF Power Limits for FR1:
| Carrier Frequency | Channel Bandwidth | OFF Power Limit |
|---|---|---|
| f ≤ 3 GHz | BW ≤ 40 MHz | -48.5 dBm |
| BW ≤ 100 MHz | -48.3 dBm | |
| 3 < f ≤ 6 GHz | - | -48.2 dBm |
The table below shows UE OFF Power Limits for FR2:
| Carrier Frequency | Channel Bandwidth | OFF Power Limit |
|---|---|---|
| - | - | -30 dBm |
The following image shows various regions of the PVT measurement.
The NR PVT measurement measures the power in the following segments:
OFF Power Before—This segment is defined as the OFF-power region before the captured burst. The length is defined for at least 1 slot excluding any transient periods.
ON Power—This segment is defined as the ON-power region in the captured burst excluding any transient periods. The length of this region depends on the signal configuration used for the transmission. The length of the captured burst is calculated by the measurement automatically.
OFF Power After—This segment is defined as the OFF-power region after the captured burst. The length is defined as at least 1 slot excluding any transient periods.
The NR PVT measurement is supported only with the triggered acquisitions: IQ Power Edge Trigger and Digital Edge Trigger. In case of Digital Edge Trigger, a marker is expected at the start of a frame.
Measurement Overview Downlink PVT
According to 3GPP (38.104, 38.141-1, 38.141-2) for Downlink PVT, the OFF power spectral density is measured over 70/N µs (N = SCS/15, where SCS is Sub Carrier Spacing in kHz) filtered with a square filter of bandwidth equal to the RF bandwidth. The measured OFF power spectral density in the time window from 35/N µs after end of one transmitter ON period (excluding transient time) to 35/N µs before start of next transmitter ON period (excluding transient time) shall not exceed the limits specified in 38.141-1 for conducted testing and 38.141-2 for radiated testing.
Depending on the base station type being either BS type 1-C, BS type 1-O or BS type 2-O the limits for FR1 conducted, FR1 radiated or FR2 radiated are selected as shown in the tables below.
The base station type can be configured by gNodeB Type property. The additional rated power parameters Prated,c,EIRP and Prated,c,TRP required to calculate the limits for Base Station Type 2-O can be configured by the properties Rated TRP (dBm) and Rated EIRP (dBm).
The table below shows OFF Power Limits for BS type 1-C:
| Carrier Frequency | OFF Power Limit |
|---|---|
| f ≤ 3 GHz | -81 dBm/MHz |
| 3 < f ≤ 6 GHz | -80 dBm/MHz |
The table below shows OFF Power Limits for Base Station Type 1-O:
| Carrier Frequency | OFF Power Limit |
|---|---|
| f ≤ 3 GHz | -99.2 dBm/MHz |
| 3 < f ≤ 6 GHz | -98.8 dBm/MHz |
The table below shows OFF Power Limits for Base Station Type 2-O:
| Carrier Frequency | OFF Power Limit |
|---|---|
| 24.15 < f ≤ 29.5 GHz | -30.2 + Prated,c,EIRP - Prated,c,TRP dBm/MHz |
| 37 < f ≤ 43.5 GHz | -29.4 + Prated,c,EIRP - Prated,c,TRP dBm/MHz |
The Downlink PVT measurement is performed as follows:
The signal is acquired depending on the configured trigger and measurement interval. NR Downlink PVT measurement supports IQ Power Edge Trigger and Digital Edge Trigger marking the start of a frame. The length of the acquired signal is controlled by the properties Measurement Interval Auto and Measurement Interval (s). If you set Measurement Interval Auto to True, the acquisition length is automatically derived from the signal configuration such that the measurement spans the first sequence of ON-OFF-ON regions. If you set Measurement Interval Auto to False, the acquisition length is configured such that the measurement spans the configured Measurement Interval (s). In this case, all ON and OFF segments identified in the acquired signal are used for measurement.
With the acquired data, the instantaneous signal power and the 70/N µs windowed signal power is calculated. In addition, the location of the ON regions and the location of the regions where the OFF power limit applies are derived.
The Downlink PVT measurement calculates the following measurement results:
Peak Windowed OFF Power (dBm/MHz) — This result returns the peak power value of the 70/N µs windowed power among all OFF regions in the measurement interval in dBm/MHz.
Peak Windowed OFF Power Margin (dB) — This result returns the margin of the Peak Windowed OFF Power to the 3GPP limit.
Peak Windowed OFF Power Time (s) — This result returns the time offset where the Peak Windowed OFF Power was measured.
ON Power — Returns the average ON power in dBm of all ON regions within the measurement interval.
NR PVT Dynamic Range Mode
PVT measurement provides a high dynamic range measurement mode to handle the 3GPP ON-OFF power measurement requirements.
For example, in frequency range 1, an NR UE transmits the maximum power of +26 dBm, the OFF-power limit being -50 dBm, and the dynamic range required is around 75 dB. For frequency range 2, an NR UE might transmit at 55 dBm EIRP, which, with the OFF-power limit being -30 dBm, would require the dynamic range to be around 85 dB. The theoretical OFF power limit can go even lower based on the thermal noise floor. For example, for 20 MHz bandwidth, the OFF-power value is -96 dBm; for 10 MHz bandwidth, the OFF-power value is -99 dBm; and so on. To measure this OFF power accurately, the dynamic range needed is very high (~120 dB) and none of the available instruments in the market provide this dynamic range. NR PVT dynamic range mode provides a dual acquisition solution to achieve the required dynamic range.
The first acquisition captures the I/Q with a user-defined reference level, which will measure the ON power accurately. However, the OFF power will not be represented adequately due to the limited dynamic range of the device, which leads to an inaccurate measurement of the OFF power. To solve this, a second acquisition is done at a lower reference level, which ensures the OFF-power regions are represented adequately. These two acquisitions are combined by the measurement to get a composite power trace having an OFF region from the second acquisition and an ON region from the first acquisition as shown in the picture below. The power measurement is done on this composite trace.
Supported Devices: PXIe-5644/5645/5646/5830/5831/5832/5840/5841
NR PVT OFF Power Exclusion Periods
The NR PVT measurement allows to extend the transient duration separately for the ON-OFF and OFF-ON transition regions by assigning a non-zero value to the properties OFF Power Exclusion Before (s) and OFF Power Exclusion After (s).
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Note The OFF region shrinks after the exclusion period is applied. The OFF region cannot be expanded because only positive value is supported. |
The default value for the OFF Power Exclusion Before property and OFF Power Exclusion After property is 0, which ensures it adheres to the 3GPP definition. The maximum time value is limited to 100 µs on both the sides.