Maximum RAT output power

Description

Maximum RAT output power is a base station RF parameter that defines the total output power a multi-standard radio (MSR) base station may deliver for all carriers belonging to one radio access technology. It is measured as the sum of the power of all carriers of the same RAT available at the antenna connector under a specified reference condition. The parameter is central to the RF specifications for multi-standard radio base stations, which support the simultaneous operation of multiple RATs such as GSM, UTRA, and LTE, and later NR, within a common hardware platform and often within a common frequency band.

In an MSR base station, the total transmit power is shared among the supported RATs. Each RAT has its own set of carriers, and the power allocated to each carrier depends on traffic, scheduling, and power control. The Maximum RAT output power sets a ceiling on the aggregate power for one RAT, ensuring that the combined power of all its carriers does not exceed a declared value. This is distinct from the total base station output power, which covers all RATs together, and from per-carrier maximum output power, which applies to a single carrier.

The parameter is essential for conformance testing of MSR base stations. Test specifications define reference conditions, measurement bandwidths, and procedures to verify that the sum of carrier powers for a given RAT stays within the declared maximum. Because carriers of different RATs may be interleaved in frequency, the measurement must isolate the carriers belonging to the RAT under test, which requires careful filtering and power summation. The declared Maximum RAT output power is also used in coexistence and blocking analyses, since it determines the worst-case power that can leak into adjacent bands or victim receivers.

From an operator perspective, Maximum RAT output power is a planning and configuration parameter. It allows an operator to cap the power of one RAT while leaving headroom for another, for example limiting LTE power to protect a co-sited UMTS carrier, or vice versa. It also supports power sharing strategies in which the total available power is dynamically distributed among RATs according to traffic demand, subject to per-RAT maxima. This flexibility is a key benefit of MSR base stations, which reduce site count and hardware cost compared with separate per-RAT equipment.

The definition was introduced in Rel-9 as MSR base station specifications were developed, and it has been carried forward essentially unchanged through Rel-19. The only editorial variation is the presence or absence of the leading article 'The' in the definition text; the technical meaning — the sum of the power of all carriers of the same RAT at the antenna connector under a specified reference condition — has remained constant.

Purpose & Motivation

Maximum RAT output power exists to make multi-standard radio base stations manageable and testable. When a single base station supports several RATs, the total power budget must be divided among them, and without a per-RAT limit there would be no clear way to declare, verify, or plan the power allocated to each technology. The parameter provides that limit, enabling regulators and operators to know the worst-case power a RAT can emit.

The concept solves the problem of power sharing in shared hardware. Separate base stations for GSM, UMTS, and LTE each have their own power amplifiers and their own maximum output power declarations. An MSR base station combines them, so a new abstraction is needed: power per RAT. This abstraction supports flexible power allocation, coexistence analysis, and conformance testing in a single framework.

Historically, the term was introduced in Rel-9 alongside the first MSR base station specifications. Earlier releases assumed one RAT per base station, so a per-RAT aggregate power concept was unnecessary. As MSR and later multi-RAT NR deployments became common, the parameter remained the standard way to express per-technology power limits, and its definition has proven stable across more than a decade of releases.