Description
Spectrum Reallocation is a broad operational and regulatory process involving the change in assignment of specific frequency bands from one use to another. In the 3GPP context, it encompasses technical mechanisms, network procedures, and policy frameworks that allow for the flexible and efficient use of the radio frequency spectrum. This can occur on multiple levels: reallocating spectrum between different mobile generations (e.g., refarming 2G/3G spectrum for 4G/5G), between different operators, or between mobile and other services like broadcasting. The 3GPP specifications provide the technical enablers within the Radio Access Network (RAN) and core network to support such transitions.
From a technical standpoint, SR involves a complex set of actions. For network operators, it requires careful planning to migrate user equipment and network infrastructure from one band to another with minimal service disruption. This involves updates to network configuration databases, broadcast system information, and handover parameters. Specifications like TS 36.331 (RRC protocol) and TS 38.331 define how the network can inform UEs about available frequency bands and direct them to new carriers. The process is managed through Operations, Administration, and Maintenance (OAM) systems, as detailed in specs like TS 28.xxx and 32.xxx series, which orchestrate the reconfiguration of network elements.
The role of SR in the network is fundamentally about optimization and evolution. It allows network operators to respond to technological shifts and market demands by reusing their most valuable asset—spectrum licenses. For example, as LTE and NR technologies offer superior spectral efficiency compared to older 2G/3G technologies, reallocating spectrum to them increases overall network capacity and data rates. Furthermore, SR is essential for implementing spectrum sharing techniques like Licensed Shared Access (LSA) or Dynamic Spectrum Sharing (DSS), where spectrum can be dynamically allocated between different tenants or technologies based on real-time demand, as explored in specifications like TS 37.870.
Purpose & Motivation
Spectrum Reallocation exists to solve the fundamental problem of spectrum scarcity and inefficient use. The radio frequency spectrum is a finite natural resource, and large portions are already licensed for specific services. The purpose of SR is to maximize the utility and economic value of this resource by allowing its assignment to evolve alongside technological advancements and changing user demands. Without SR, spectrum could remain locked in legacy, inefficient uses, hindering the deployment of new, higher-capacity technologies.
Historically, the motivation for SR grew with each generational transition. The shift from 2G (GSM) to 3G (UMTS) required new spectrum bands, but also created an opportunity to refarm GSM spectrum for UMTS. This need became more pronounced with 4G LTE and 5G NR, which require wider contiguous bandwidths for high throughput. Regulatory bodies worldwide have driven SR initiatives to repurpose bands, such as the digital dividend (700 MHz band) from broadcast TV to mobile broadband. 3GPP standards had to evolve to support these reallocated bands and the coexistence mechanisms required during transition periods.
SR addresses the limitations of static spectrum allocation. A static model cannot adapt to the explosive growth of mobile data traffic or the emergence of new use cases like massive IoT or ultra-reliable low-latency communications. SR provides the framework—both regulatory and technical—to enable a more dynamic, market-driven, and efficient spectrum ecosystem. It is a key tool for network operators to modernize their networks, for regulators to promote competition and innovation, and for ensuring that spectrum serves the greatest public benefit.
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (66 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-8, normative work from Rel-15.
In Release 15, the SR function was enhanced with specific corrections and clarifications, including refinements to SR triggering for configured grants and its interaction with SPS BSR. Procedures for SR cancellation, handling when triggered by a BSR, and the ordering of P-CSI plus SR in enhanced Carrier Aggregation (eCA) were also corrected.
- Support maximum 8 SS/PBCH blocks for unpaired spectrum beyond 2.4GHz TS 38.213CR0006
- Correction to SR with SPS BSR in 36.321 TS 36.321CR1324
- Clarification to trigger for SR TS 36.321CR1336
- Correction to SR triggering to accommodate the configured grant TS 38.321CR0115
- CR on SR cancellation TS 38.321CR0328
- Correction on SR with PUSCH resource handling of Semi-Persistent CSI reporting TS 38.321CR0376
+ 3 more changes
In Release 16, the SR (Scheduling Request) function was enhanced to support new operations with shared and unlicensed spectrum. Key introductions included specific SR reporting procedures for consistent Listen-Before-Talk (LBT) failure recovery and corrections to the SR procedure for sidelink Buffer Status Reporting (BSR). Furthermore, the release introduced PUCCH multiplexing with Semi-Persistent Scheduling (SPS) HARQ-ACK or an SR within a sub-slot, optimizing signaling for these new spectrum access modes.
- Mobility to NR operating with shared spectrum access TS 36.331CR4263
- Introduction of NR based access to unlicensed spectrum into 38.212 TS 38.212CR0023
- Introduction of shared spectrum channel access TS 38.213CR0071
- Introduction of NR operation with Shared Spectrum Access to Stage 2 TS 38.300CR0199
- Corrections on shared spectrum channel access TS 38.213CR0091
- Introduction of half-duplex operation in CA with unpaired spectrum TS 38.213CR0097
+ 17 more changes
In Release 17, the enhancements for Spectrum Reallocation focused on improving NR Dynamic Spectrum Sharing, including specific corrections to its procedures in 38.212. The release also introduced corrections for PDCCH monitoring and UE processing times for shared spectrum channel access in the FR2-2 band, as well as handling collisions and multiplexing for SR, NACK-only, and CSI on the PUCCH.
- Introduction of NR dynamic spectrum sharing enhancements TS 38.212CR0093
- Introduction of dynamic spectrum sharing enhancements in NR TS 38.213CR0269
- Introduction of NR dynamic spectrum sharing TS 38.300CR0400
- Corrections on NR dynamic spectrum sharing enhancements in 38.212 TS 38.212CR0105
- Corrections on dynamic spectrum sharing enhancements in NR TS 38.213CR0299
- Corrections on dynamic spectrum sharing enhancements in NR TS 38.213CR0327
+ 8 more changes
In Release 18, key SR (Scheduling Request) related enhancements included corrections and clarifications to existing procedures. Specifically, this involved corrections to the prioritization between an SR and a Sidelink Positioning Reference Signal (SL-PRS) transmission, and to the logic for terminating an ongoing Random Access Channel (RACH) procedure due to a pending SR for a Sidelink Buffer Status Report (SL-BSR). Other corrections addressed available Uplink Shared Channel (UL-SCH) resources in SR triggering and SR procedures for multi-TRP Beam Failure Recovery (mTRP BFR).
- Introduction of NR support for dedicated spectrum less than 5MHz for FR1 TS 36.331CR4983
- Introduction of Rel-18 NR support for dedicated spectrum less than 5MHz for FR1 TS 38.212CR0154
- Introduction of dynamic spectrum sharing (DSS) enhancements TS 38.213CR0500
- Introduction of NR support for dedicated spectrum less than 5MHz for FR1 TS 38.213CR0502
- Introduction of dynamic spectrum sharing enhancements TS 38.214CR0443
- Introduction of NR support for dedicated spectrum less than 5MHz for FR1 TS 38.214CR0494
+ 9 more changes
In Release 19, the SR (Spectrum Reallocation) function was enhanced to introduce SR-triggered SSSG (Serving Cell/Serving Cell Group) switching and to include SR resources within the LTM (Long Term Measurement) cell switch MAC CE. These changes were further refined through subsequent corrections to the SR-triggered SSSG switching procedure.
- Introduction of SR triggered SSSG switching [SRTrig_SSSGSwitch] TS 38.213CR0713
- Introducing SR resources in LTM cell switch MAC CE [LTM_enh_SR] TS 38.300CR1054
- Introducing SR resources in LTM cell switch MAC CE [LTM_enh_SR] TS 38.321CR2130
- Corrections on SR triggered SSSG switching [SRTrig_SSSGSwitch] TS 38.213CR0747
- Conditionally mandatory support for inter-RAT configuration for dedicated spectrum less than 5MHz for NR FR1 TS 36.306CR1941
Explore further
Broader topics and technologies where SR plays a role.
Defining Specifications
3GPP specifications that define or reference SR, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TR 22.804 vg30 | 5G Automation in Vertical Domains Study | Rel-16 |
| TS 25.800 vc10 | UMTS Heterogeneous Networks Study | Rel-12 |
| TS 26.114 vj10 | IMS Multimedia Telephony Media Handling | Rel-19 |
| TS 26.260 vj00 | Immersive Audio Objective Test Methods | Rel-19 |
| TS 26.565 vj00 | Split Rendering Media Service Enabler | Rel-19 |
| TS 26.567 vj00 | IMS-based Split Rendering | Rel-19 |
| TS 29.549 vj40 | SEAL API Specification for Vertical Applications | Rel-19 |
| TS 29.892 vg00 | Study on User Plane Protocol in 5GC | Rel-16 |
| TR 33.916 vj00 | 3GPP Security Assurance Methodology (SECAM) | Rel-19 |
| TS 36.212 vj10 | LTE Multiplexing and Channel Coding | Rel-19 |
| TS 36.213 vj10 | LTE Physical Layer Procedures | Rel-19 |
| TS 36.300 vj00 | E-UTRAN Radio Interface Protocol Architecture Overview | Rel-19 |
| TS 36.306 vj00 | E-UTRA UE Radio Access Capability Parameters | Rel-19 |
| TS 36.321 vj00 | E-UTRA MAC Protocol Specification | Rel-19 |
| TS 36.331 vj00 | LTE RRC Protocol Specification | Rel-19 |
| TS 36.822 vb00 | LTE RAN Enhancements for Diverse Data Apps | Rel-11 |
| TS 37.870 vd00 | Study on Multi-RAT Joint Coordination | Rel-13 |
| TS 38.212 vj10 | NR Multiplexing and Channel Coding | Rel-19 |
| TS 38.213 vj10 | NR Physical Layer Control Procedures | Rel-19 |
| TS 38.214 vj10 | NR Physical Layer Procedures for Data | Rel-19 |
| TS 38.300 vj00 | NG-RAN Overall Description | Rel-19 |
| TS 38.321 vj00 | NR MAC Protocol Specification | Rel-19 |
| TR 38.825 vg00 | Study on NR Industrial IoT | Rel-16 |
| TR 38.830 vh00 | NR Coverage Enhancements Study | Rel-17 |
| TR 38.838 vh00 | Study on XR Evaluations for NR | Rel-17 |