Satellite Access Node Type 1-H

Description

SAN type 1-H is a classification of Satellite Access Node (SAN) defined in 3GPP specifications 36.108 and 38.108 for Non-Terrestrial Networks (NTN). It refers to a SAN that operates at FR1-NTN (frequency range 1 for NTN, typically below 7.125 GHz) and has a requirement set consisting of conducted requirements defined at individual TAB connectors and OTA (Over-The-Air) requirements defined at RIB (Radiated Interface Boundary). This hybrid approach allows for flexible testing and validation of SAN RF performance.

In the context of 3GPP, base station types are categorized based on their architecture and testing requirements. For terrestrial base stations, types like 1-O, 1-H, and 2-O are defined in TS 38.104. SAN type 1-H extends this concept to satellite access nodes. The '1-H' designation indicates that the SAN has multiple TAB connectors (antenna ports) and that some requirements are tested via conducted connections at these connectors, while others are tested OTA at the RIB. This is particularly relevant for satellite payloads, which may have complex antenna arrays and cannot always be tested solely via conducted means.

The TAB connector is the interface point where conducted measurements are made, typically a coaxial or waveguide port. Conducted requirements include parameters like output power, ACLR, and spurious emissions, which can be measured directly at the connector. OTA requirements, on the other hand, are measured at the RIB, which is the boundary where radiated fields are assessed. OTA requirements include radiated power, unwanted emissions in the spatial domain, and beam characteristics. The combination of conducted and OTA requirements ensures comprehensive verification of the SAN's RF performance.

SAN type 1-H is specifically defined for FR1-NTN, which encompasses frequency bands allocated for satellite communications in the sub-7 GHz range. These bands may be shared with terrestrial networks, making interference management critical. The hybrid testing approach allows manufacturers to demonstrate compliance with both conducted and radiated requirements, which is essential for regulatory approval and interoperability. It also accommodates the practical constraints of testing satellite payloads, where full OTA testing may be challenging due to size, cost, or lack of suitable test facilities.

The definition of SAN type 1-H is part of a broader framework for SAN types. Other types may include SAN type 1-O (fully OTA) or SAN type 2-O (for higher frequency ranges like FR2-NTN). The type designation helps in specifying the applicable requirements and test methods. For engineers, understanding SAN type 1-H is crucial for designing and validating satellite access nodes that comply with 3GPP standards.

In summary, SAN type 1-H is a standardized classification that defines how a Satellite Access Node at FR1-NTN should be tested, combining conducted and OTA requirements. It ensures that SANs meet performance and emission limits, facilitating their integration into 5G NTN networks.

Purpose & Motivation

SAN type 1-H exists to provide a standardized framework for testing and validating the RF performance of Satellite Access Nodes operating in FR1-NTN. It addresses the unique challenges of satellite payload testing, where traditional conducted-only or OTA-only approaches may not be sufficient or practical. By combining conducted requirements at TAB connectors with OTA requirements at the RIB, it enables a comprehensive assessment of the SAN's emissions and reception characteristics.

The motivation for SAN type 1-H stems from the need to integrate satellite access into 5G NR while ensuring compliance with regulatory limits and minimizing interference with terrestrial networks. Before its introduction, satellite systems often used proprietary testing methods, which hindered interoperability and spectrum sharing. The 3GPP definition of SAN types, including type 1-H, provides a common language for manufacturers, operators, and regulators.

Furthermore, the hybrid approach of SAN type 1-H solves the problem of testing large antenna arrays and complex payloads. Conducted measurements at TAB connectors allow precise, repeatable testing of parameters like power and emissions, while OTA measurements at the RIB capture the radiated behavior of the antenna system. This dual approach is particularly important for FR1-NTN, where spectrum is scarce and interference must be tightly controlled.

In essence, SAN type 1-H facilitates the deployment of NTN by ensuring that SANs meet stringent RF requirements. It is a key enabler for the coexistence of satellite and terrestrial networks in shared frequency bands, supporting the vision of ubiquitous 5G coverage.