Exclusion Band

Description

An exclusion band is a designated frequency range within which a device or system is not required to meet certain RF performance requirements, particularly in the context of spurious emissions and unwanted emissions testing. In 3GPP specifications, exclusion bands are defined to account for known phenomena such as harmonics, intermodulation products, or other spurious responses that may fall outside the intended operating band but are inherent to the design. By excluding these ranges from assessment, the standards avoid imposing unrealistic or technically infeasible requirements on equipment.

The concept is primarily applied in the testing of User Equipment (UE) and base stations (BS) for radio frequency (RF) compliance. For example, 3GPP TS 38.113 (BS EMC), TS 38.114 (UE EMC), and TS 38.175 (BS RF requirements) specify exclusion bands for various frequency ranges. These bands are typically defined relative to the carrier frequency or the operating band, and they may vary depending on the frequency range (FR1 or FR2) and the specific test case. The exclusion bands are often listed in tables within the specifications, detailing the start and stop frequencies.

The purpose of exclusion bands is to streamline the certification process. Without them, every possible spurious emission would need to be tested, which could be time-consuming and costly, especially for wideband systems. Exclusion bands are determined based on the characteristics of the transmitter and receiver, such as the local oscillator frequencies, intermediate frequencies, and known spurious responses. They are also used in the context of coexistence studies, where the impact of spurious emissions on other systems is evaluated.

In the evolution of 3GPP releases, the definition of exclusion band has remained largely consistent, indicating its stable role in RF testing. However, the specific frequency ranges and conditions may be updated as new bands and technologies are introduced. For instance, with the advent of 5G NR, exclusion bands have been defined for new frequency ranges (FR1: 410 MHz – 7.125 GHz, FR2: 24.25 GHz – 52.6 GHz) to accommodate the unique characteristics of millimeter-wave transmissions.

Overall, exclusion bands are a practical tool in the 3GPP framework, balancing the need for rigorous RF compliance with the realities of hardware design. They ensure that testing focuses on the most critical emissions while allowing for known, unavoidable spurious signals.

Purpose & Motivation

Exclusion bands exist to address the practical challenges of RF testing in complex wireless systems. In early cellular systems, testing every possible spurious emission was feasible, but as systems became more wideband and complex, the number of potential spurious responses grew exponentially. Exclusion bands were introduced to define specific frequency ranges where emissions are not assessed, typically because they are caused by inherent hardware characteristics such as harmonics or intermodulation products that cannot be easily suppressed. This approach prevents unnecessary testing and reduces the burden on manufacturers, while still ensuring that critical emissions outside the exclusion bands are controlled. The concept has evolved with each generation, adapting to new frequency bands and technologies, but its fundamental goal remains: to provide a pragmatic balance between regulatory compliance and technical feasibility.