Integrated Access and Backhaul Type 1-H

Description

IAB type 1-H is a specific node type for Integrated Access and Backhaul (IAB) defined in 3GPP Release 19 specifications (TS 38.174, TS 38.175). IAB enables wireless backhaul for 5G New Radio (NR) by using the same spectrum for both access and backhaul links. An IAB node consists of an IAB-DU (Distributed Unit) that serves UEs and child IAB nodes, and an IAB-MT (Mobile Termination) that connects to a parent IAB node or donor. The type 1-H designation refers to the radio frequency (RF) requirements for IAB nodes operating in Frequency Range 1 (FR1), which covers sub-6 GHz bands. The 'H' likely stands for 'hybrid' or indicates a specific requirement set that combines conducted and over-the-air (OTA) test methodologies.

The key characteristic of IAB type 1-H is its requirement set: it includes conducted requirements defined at individual TAB connectors (Test Access Board connectors, which are RF test points) and OTA requirements defined at the RIB (Radiated Interface Boundary). This hybrid approach allows for testing both conducted and radiated performance, which is essential for IAB nodes that may have integrated antennas or multiple antenna arrays. Conducted requirements at TAB connectors enable precise measurement of transmitter and receiver characteristics without antenna effects, while OTA requirements at RIB account for the actual radiated performance including antenna gain, beamforming, and spatial characteristics. This dual approach ensures that IAB nodes meet both component-level and system-level performance criteria.

In the IAB architecture, an IAB node can function as a parent or child in a multi-hop backhaul chain. The IAB-DU provides NR access to UEs and backhaul to child IAB nodes, while the IAB-MT connects to the parent node's IAB-DU. The type 1-H requirements are crucial for ensuring interoperability and performance in FR1 deployments, which are common for wide-area coverage. The specifications TS 38.174 and TS 38.175 define the RF requirements for IAB nodes, including frequency bands, power classes, and test procedures. Type 1-H specifically addresses the need for flexible testing methodologies that accommodate different antenna configurations and integration levels.

The introduction of IAB type 1-H in Release 19 reflects the ongoing evolution of 5G networks towards more flexible and cost-effective deployments. IAB allows operators to deploy small cells without the need for fiber backhaul, reducing deployment costs and time. The type 1-H requirements ensure that IAB nodes can be tested and certified consistently, facilitating multi-vendor interoperability. This is particularly important for FR1 bands, which are widely used for 5G coverage and capacity. The hybrid requirement set also supports the development of advanced antenna systems, such as massive MIMO, which are integral to 5G performance.

In summary, IAB type 1-H is a technical specification for IAB nodes operating in FR1, defining a hybrid set of conducted and OTA RF requirements. It plays a vital role in enabling flexible and efficient 5G deployments by ensuring that IAB equipment meets stringent performance standards.

Purpose & Motivation

IAB type 1-H was created to address the specific RF testing and performance requirements for Integrated Access and Backhaul nodes operating in Frequency Range 1 (FR1). As 5G networks evolve, IAB is seen as a key technology to enable cost-effective and rapid deployment of small cells without fiber backhaul. However, testing IAB nodes presents unique challenges because they integrate both access and backhaul functions, often with advanced antenna systems. Traditional conducted testing alone is insufficient for nodes with integrated antennas, while OTA testing alone may not provide the precision needed for component-level verification. The hybrid requirement set of type 1-H solves this by combining conducted requirements at TAB connectors and OTA requirements at RIB, allowing for comprehensive verification of both conducted and radiated performance. This ensures that IAB nodes can meet the stringent performance criteria required for reliable operation in FR1 bands, facilitating multi-vendor interoperability and accelerating the adoption of IAB technology. The introduction in Release 19 reflects the maturity of IAB specifications and the need for standardized testing methodologies as IAB moves towards commercial deployment.