Three Dimensional

Description

In 3GPP, the term 3-D (Three Dimensional) encompasses three-dimensional channel modelling, three-dimensional antenna arrays, and three-dimensional spatial processing for radio access networks. It was introduced in Release 8 and has been refined across Releases 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, and 19. The relevant specifications include TS 25.914 (UTRA spatial channel model), TS 34.114 (UE antenna modelling), TS 37.544 (3D channel model for LTE and NR), and TS 37.902 (measurement of radiated performance). The concept is fundamental to modern MIMO and beamforming because it extends the traditional two-dimensional (azimuth-only) channel and antenna models into the elevation domain.

Architecturally, 3-D modelling affects the base station antenna array, the propagation channel, and the UE antenna. In a 3-D system, the base station uses a two-dimensional planar array with elements arranged in rows and columns, allowing beam steering in both azimuth and elevation. The channel model must then account for elevation angles of departure and arrival, as well as the height of scatterers and the UE. TS 37.544 defines the 3D spatial channel model (SCM) used for LTE and NR evaluations, including parameters such as zenith angle spread and elevation angle spread. This enables accurate simulation of full-dimensional MIMO (FD-MIMO) and massive MIMO systems.

Key components of 3-D technology include the antenna array geometry, the radiation pattern of each element, the polarization, and the propagation environment. The UE side is also modelled in 3-D, as described in TS 34.114, which specifies UE antenna characteristics for MIMO and radiated testing. TS 37.902 addresses the measurement of radiated performance, which is essential for verifying 3-D beamforming devices in anechoic chambers or reverberation chambers. Together, these specifications provide a complete framework for designing, simulating, and testing 3-D wireless systems.

The role of 3-D in the network is to improve coverage and capacity by exploiting the vertical dimension. Elevation beamforming can direct energy toward users on different floors of a building, reduce interference to neighbouring cells, and increase spectral efficiency. In dense urban environments, 3-D MIMO is a key enabler for meeting capacity demands. It also supports advanced features such as multi-user MIMO, where users are separated in both azimuth and elevation, and 3-D beam management for NR.

Overall, 3-D is a foundational concept that spans channel modelling, antenna design, and system evaluation. Its evolution from Rel-8 to Rel-19 reflects the growing importance of spatial processing in cellular networks, from early MIMO studies to the massive MIMO and beamforming capabilities of 5G NR.

Purpose & Motivation

The 3-D concept exists to address the limitations of two-dimensional channel and antenna models that only considered the azimuth plane. Early MIMO systems assumed that signals propagated horizontally, ignoring elevation. This assumption became inadequate as antenna arrays grew larger and as deployments in dense urban environments required precise control of the vertical radiation pattern. Three-dimensional modelling allows engineers to accurately predict and exploit elevation beamforming, which improves coverage and reduces interference.

Historically, 3GPP introduced 3-D channel modelling in Release 8 for UTRA and later extended it to LTE and NR. The initial motivation was to support advanced antenna systems with vertical beamforming, which were being deployed to enhance capacity. As massive MIMO emerged in Releases 13 and 14, the need for accurate 3-D models became critical because the performance of large arrays depends heavily on elevation angles and scatterer heights. The specifications TS 37.544 and TS 34.114 were developed to provide standardized models for system-level and link-level simulations.

The 3-D concept also solves the problem of testing and measuring devices with integrated antennas. TS 37.902 defines radiated performance measurement methods that account for three-dimensional radiation patterns, ensuring that UE and base station designs meet regulatory and performance requirements. Without 3-D modelling, the industry would lack a common framework for evaluating beamforming gains and for comparing different antenna designs, leading to inconsistent performance claims and inefficient deployments.