Rated carrier Total Radiated Power

Description

Rated carrier Total Radiated Power (TRP) is a parameter defined in 3GPP specifications for base stations that employ active antenna systems (AAS) and are tested using over-the-air (OTA) methodologies. It represents the mean power level per carrier that the manufacturer declares to be available at the radiated interface boundary (RIB) during the transmitter ON period. This parameter is essential for verifying the radiated power of AAS base stations, where traditional conducted measurements at the antenna connector are not possible because the antenna is integrated with the radio unit.

The concept of rated carrier TRP is closely related to the total radiated power, which is the integral of the radiated power density over the entire sphere surrounding the base station. However, rated carrier TRP is specific to a particular carrier and is declared by the manufacturer for base stations operating in single-carrier, multi-carrier, or carrier aggregation configurations. It is measured during the transmitter ON period under specified reference conditions, ensuring consistency and repeatability. The parameter is specified in 3GPP technical specifications 37.145 (Active Antenna System Base Station conformance testing) and 38.141 (NR Base Station conformance testing).

In practice, rated carrier TRP is used in conformance testing to ensure that the base station does not exceed the declared power level, which could cause interference to other systems or violate regulatory requirements. The measurement is typically performed in an anechoic chamber or using a near-field to far-field transformation, as the TRP is defined in the far-field region. The RIB is a virtual surface that encloses the base station and is used as the reference for radiated measurements. The rated carrier TRP is the power that passes through this surface.

The parameter is particularly important for millimeter wave (FR2) base stations, where the small wavelength allows for highly integrated antenna arrays and OTA testing is the only viable option. It is also applicable to FR1 base stations with AAS. The rated carrier TRP is declared per carrier, and for multi-carrier or carrier aggregation configurations, the total TRP may be subject to additional limits to ensure compliance with electromagnetic field (EMF) exposure regulations.

Overall, rated carrier TRP is a crucial parameter for the design, testing, and deployment of AAS base stations. It provides a standardized way to declare and verify the radiated power per carrier, which is essential for ensuring coexistence, regulatory compliance, and efficient use of the spectrum. As 5G NR continues to evolve towards higher frequencies and more advanced antenna systems, the accurate declaration and measurement of rated carrier TRP will remain essential.

Purpose & Motivation

The rated carrier TRP parameter was introduced to address the need for a standardized metric to declare and verify the radiated power of active antenna system (AAS) base stations. Traditional conducted power measurements at the antenna connector are not applicable to AAS because the antenna is integrated with the radio unit, and the power cannot be measured at a physical connector. The rated carrier TRP solves this problem by defining a radiated power metric that can be measured over the air and used in conformance testing.

Before the introduction of this parameter, there was no consistent way to declare the radiated power for AAS base stations, leading to potential ambiguities in testing and regulatory compliance. The rated carrier TRP provides a clear, measurable quantity that represents the total radiated power per carrier at the RIB. This is essential for ensuring that the base station complies with regulatory limits on radiated power and for facilitating coexistence with other systems.

Furthermore, with the deployment of 5G NR in millimeter wave bands, OTA testing became mandatory due to the lack of physical connectors. The rated carrier TRP was developed to support this paradigm shift, enabling manufacturers to declare the radiated power of their AAS base stations and allowing test houses to verify it using OTA methods. This parameter is a key enabler for the commercialization of 5G NR in high-frequency bands.