Description
In 3GPP terminology, a beam refers to the main lobe of the radiation pattern of an antenna array. This definition, introduced in Release 12, reflects the growing importance of beamforming techniques in cellular networks. A beam is characterized by its direction, width, and gain, and it represents the spatial concentration of radiated energy. By forming beams, an antenna array can direct signals towards intended users while reducing interference to others, thereby improving spectral efficiency and coverage.
Beamforming is achieved by adjusting the phase and amplitude of signals fed to individual antenna elements in an array. This creates constructive interference in desired directions and destructive interference elsewhere. In 5G NR, beamforming is a cornerstone technology, especially in millimeter-wave bands where propagation losses are high and directional transmission is essential. The network can generate multiple beams, either dynamically or in a grid-of-beams fashion, to serve users across a cell.
The concept of a beam is closely tied to beam management procedures in 5G NR, which include beam sweeping, beam measurement, beam determination, and beam reporting. These procedures enable the network and the user equipment (UE) to align their beams for optimal link quality. Beams can be classified as transmit beams at the base station (gNB) or receive beams at the UE, and they can be either static or dynamically steered.
3GPP specifications such as 38.104 (NR Base Station radio transmission and reception), 38.141 (NR Base Station conformance testing), and 37.105 (Active Antenna System base station radio conformance testing) define requirements for beam characteristics, including beamwidth, gain, and sidelobe suppression. These specifications ensure that beams meet regulatory and performance standards.
Over releases, the definition of beam has remained consistent, but its application has expanded with the introduction of new frequency bands and advanced antenna systems. The term is now ubiquitous in discussions of 5G and beyond, where beam-based communication is fundamental to achieving the ambitious performance targets of IMT-2020.
Purpose & Motivation
The concept of a beam exists to describe the directional radiation pattern of an antenna array, which is essential for advanced antenna technologies like beamforming and massive MIMO. Before the widespread adoption of beamforming, cellular networks primarily used wide beams or sectorized antennas, which radiated energy over a broad area. This approach was inefficient in terms of power and spectrum usage, especially as demand for higher data rates grew.
Beamforming solves this by focusing energy in specific directions, thereby increasing signal strength for targeted users and reducing interference. This is particularly crucial in higher frequency bands, such as millimeter waves, where path loss is severe and directional transmission is necessary to maintain coverage. The term 'beam' provides a precise way to refer to the main lobe of the radiation pattern, distinguishing it from sidelobes and other pattern features.
The introduction of the beam definition in Release 12 coincided with the development of advanced antenna systems (AAS) and the early stages of 5G research. It allowed standards to specify performance requirements for beams, facilitating interoperability and ensuring that beamforming implementations meet quality standards. As networks evolve towards 6G, the beam concept will remain central to spatial multiplexing and ultra-reliable low-latency communications.
What changed in its specifications
The latest release-to-release comparison of specifications that define Beam. Each summary describes the whole specification, not only this term.
Rel-19 adds sub-band full duplex base station requirements to TS 38.104, plus LP-WUS text, ATG PUSCH requirements, and the new n110 band. It also adds sub-5 MHz FR1 channel bandwidth requirements and extends wide-area BS unwanted emission limits to n68, n87, n88 and n110.
Full comparison in TS 38.104 →Release Timeline
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (4 CRs across 2 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Defining Specifications
3GPP specifications that define or reference Beam, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 36.108 vk00 | Satellite Access Node RF Requirements | Rel-20 read |
| TS 37.105 vj40 | AAS Base Station Radio Requirements | Rel-19 read |
| TS 37.145 vj40 | AAS Base Station Radiated Requirements | Rel-19 read |
| TS 37.842 vd30 | BS RF Requirements for Active Antenna Systems | Rel-13 read |
| TR 37.843 vf70 | AAS BS Radiated RF Requirement Background | Rel-15 read |
| TS 38.104 vk10 | NR Base Station RF Requirements | Rel-20 read |
| TS 38.108 vk00 | NR NTN Satellite Access Node RF Requirements | Rel-20 read |
| TS 38.141 vj40 | BS Conformance Testing (TR 38.141) | Rel-19 read |
| TS 38.174 vk00 | NR Integrated Access and Backhaul Requirements | Rel-20 read |
| TS 38.817 | 3GPP TR 38.817 | Rel-12 read |
| TS 38.908 vj40 | NR n104 BS EIRP Mask and Testing | Rel-19 read |