As telecom is evolving to next generations and new use cases, 3GPP has added new Power Class Categories. As per the definition, UE Power Class can be defines as the maximum transmit power over NR channel bandwidth. The link budget is always uplink limited due to low tx power from UE and defines the cell range. When UE power is high it can make call from longer distance. 5G NR works within FR1 and FR2 frequencies ranges and 3GPP has defined UE power classes for both.
- 3GPP TS 38.101-1 specifies UE Power Classes for FR1 and 3GPP TS 38.101-2 specifies for FR2
- In FR1 frequency range, UE Power Classes are specified using cabled measurement.
- For FR2 frequency range, UE Power Classes are specified using Over The Air (OTA) measurements
- Total 4 Power Classes are defined namely, Power Class 1, Power Class 2, Power Class 3 and Power Class 4
- UEs operating within FR1 specifies Power Class 2 and Power Class 3
- UEs operating within FR2 specifies all four classes
FR1 UE Power Classes
3GPP TS 38.101-1 specifies two power classes namely Class 2 and Class 3 for FR1. Power Class 2 can transmit max output as 26 dBm and Power Class 3 max out power as 23 dBm. Power Class 2 is applicable to specific operating bands only where as Power class 3 is applicable for all frequency bands.
Power Class 2 used when following conditions are satisfied.
- if P-Max is not provided, or is configured with a value greater than 23 dBm
- if the UE has provided maxUplink.DutyCycle-PC2-FR1 within its UE capability information, then the UE operates using Power Class 2 if the percentage of uplink symbols does not exceed the value of maxUplinkDutyCycle-PC2-FR1
- if the UE has not provided maxUplinkDutyCycle-PC2-FR1 within its UE capability information, then the UE operates using Power Class 2 if the percentage of uplink symbols docs not exceed 50 %
Power Class 3 used when following conditions are satisfied.
- if P-Max is configured with a value of 23 dBm or lower then the UE operates using Power Class 3
- if the UE has provided the maxUplinkDutyCycle-PC2-FR1 IE within its UE capability information, then the UE operates using Power Class 3 if the percentage of uplink symbols exceeds the value of maxUplinkDutyCycle-PC2-FR 1
- if the UE has not provided the maxUplinkDutyCycle-PC2-FR1 information element within its UE capability information, then the UE operates using Power Class 3 if the percentage of uplink symbols exceeds 50 %
FR2 UEs Power Classes
3GPP TS 38.101-2 specifies the four Power Classes for FR2 UEs namely Power Classes 1, 2, 3 and 4. In FR2, 3GPP has specified an assumed use case/application for each UE Power Class.
- Power Class 1 devices are intended for FWA and have the highest transmit power capability. These devices can be used to provide a broadband connection at residential or offices.
- The Power Classes from 2 to 4 have equal maximum EIRP and Total Radiated Power (TRP) requirements but different minimum Peak EIRP requirements
- For the UEs, the maximum EIRP limits are is used to satisfy regulatory requirements, i.e. ensuring that devices do not transmit such high power which could cause health issue or generate excessive interference. The maximum EIRP considers maximum antenna gain which can be generated by the device. Mobile devices are specified lo have a maximum EIRP of 43 dBm, while ‘transportable’ devices arc specified to have a maximum EIRP of 55 dBm.
- The minimum Peak EIRP is used to ensure that a device can generate at least a minimum output power in one specific direction.
- Total Radiated Power (TRP) is an other requirement for a UE which defines an upper limit on the total power radiated in all directions
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