3GPP Release

Overview of 3GPP releases as on October 2022. Source: 3GPP 2022a.
Overview of 3GPP releases as on October 2022. Source: 3GPP 2022a.

3GPP regularly publishes Technical Specifications (TSs) and Technical Reports (TRs) pertaining to mobile cellular systems (2G/3G/4G/5G). These documents go by the generic term specifications. New specifications are created and existing specifications are updated as the technologies evolve. Specifications are grouped into what are called Releases. Given a particular release, a mobile system can be constructed. By adding new functionality to a release, 3GPP partners and members construct a new release.

Coming up with a new release normally takes about 2.5 years. This excludes the time to conceptualize and finalize what should go into the release.

Companies develop products conforming to a specific release. Release is therefore an important concept for feature support and interoperability. Moreover, each release is designed with backward and forward compatibility in mind.

Discussion

  • How are specifications organized and versioned?
    Numbering of 5G RAN specifications. Source: Adapted from Ghadialy 2017.
    Numbering of 5G RAN specifications. Source: Adapted from Ghadialy 2017.

    Specifications are organized into series, versioned and change-tracked. Documents within a series are closely related technically. For example, 38-series covers 5G, 36-series covers 4G and 25-series covers 3G. Within the 38-series, 38.1xx covers UE and base station requirements, 38.2xx covers PHY, 38.3xx covers radio protocols, etc.

    Every specification is versioned with a version number of the form x.y.z. Field x refers to the release. Field y increments every time technical changes are introduced and approved by the TSG. Field z increments every time editorial changes are made. Fields y and z reset to zero if the preceding fields increment.

    For example, TS 38.101-4 V17.6.0 is a TS belonging to 38-series and of Release 17. The document is in its sixth technical version with no editorial changes to that version. The suffix "-4" indicates part 4 (parts and subparts are used only for long specifications published as multiple documents).

    Field x has a few special values: 0 (draft), 1 (presented to TSG for information), and 2 (presented to TSG for approval). Once approved, x takes the value of the release number.

  • What's the typical 3GPP release process?
    3GPP working process for a release. Source: Casaccia 2017.
    3GPP working process for a release. Source: Casaccia 2017.

    Every release starts with a vision or concept of what is desired from the release. Proposals are made to add new features or services. Work formally begins when some of these proposals are accepted. Features are typically broken down into smaller elements.

    Each 3GPP TSG meets quarterly to approve Work Items. Work Items with sufficient complexity may be preceded by Study Items. Study Items result in Technical Reports (TRs) that in turn becomes inputs to writing the Technical Specifications (TSs). Either new TR/TS documents are created or existing ones are updated via Change Requests (CRs). Essentially, specifications are change controlled and can be updated only via CRs.

    A new release of a specification is either via CRs, via a request to the TSG, or automatic. If a specification is not updated during a release, it's automatically upgraded from the previous release without any changes.

    The decision-making process is non-linear, iterative and via consensus. There's no voting process at meetings. Delegates discuss and negotiate. In most cases, original proposals are refined before accepted.

  • What's meant by stage 1, 2 and 3 of a 3GPP release?
    Timeline of 3GPP Release 18. Source: 3GPP 2022e.
    Timeline of 3GPP Release 18. Source: 3GPP 2022e.

    A release is developed via a three-stage methodology that comes from ITU‑T Recommendation I.130:

    • Stage 1: Overall service description from a user's perspective.
    • Stage 2: Overall description of network functions. These map service requirements into network capabilities.
    • Stage 3: Definition of switching and signalling capabilities to support services defined in stage 1.

    A feasibility study is often conducted before defining the specifications. This may be termed Stage 0. Likewise, stage 3 may be followed with test specifications. This may be termed Stage 4.

    The figure shows Release 18 as an example. From package approval (December 2021) to protocol coding freeze (March 2024), the duration is 2 years and 3 months. Conceptualizing new features or enhancements for the release may begin as early as 12 months before the package approval. We also note that Release 18 overlaps with adjacent releases. This overlap enables continuous progress.

    Stage 3 freeze is usually 1-2 TSG meetings before protocol freeze (release end date). End date is indicative since release may be refined/corrected later.

  • Could you share more details on Change Requests?
    Illustrating three CRs on 23.456 specification. Source: Adapted from Meredith 2002, slide 31.
    Illustrating three CRs on 23.456 specification. Source: Adapted from Meredith 2002, slide 31.

    CRs add new features, clarify/correct/enhance features of an ongoing release, or correct error in functionally frozen specifications. A CR is on a TR or TS and relates to a Work Item. It should highlight sections of the specification changed and include the changes.

    CRs can undergo multiple revisions. Multiple CRs could be merged. CRs are agreed first within WGs before sent to TSG for approval. CRs can be rejected, withdrawn or postponed either at WG or TSG level. The figure shows an example of three CRs on 23.456 (fictional) specification. CRs are numbered 4, 5 and 6. Apart from CR 6, the other two have undergone revisions. When presented to the TSG plenary, all CRs of a given specification are combined into a single document along with a cover sheet.

    CRs fall into a few categories: A (change to an earlier release), B (add/delete feature), C (functional change), D (editorial change, no impact on implementation), E (not used), and F (correction). When a release is frozen, category F is permitted but other categories are generally not permitted.

  • What online resources are available to 3GPP release contributors?

    Every release has a full release description document named TR 21.9xx. For example, the document for Release 17 is TR 21.917. It can be downloaded from the 21-series page.

    The following resources are helpful:

  • Which are the main 3G releases?
    Main 3G releases. Source: Dahlman et al. 2008, fig. 1.3.
    Main 3G releases. Source: Dahlman et al. 2008, fig. 1.3.

    The first 3G release was called Release 99. It supported both circuit-switched and packet-switched bearers. It met IMT-2000 requirements set by ITU. Subsequent 3G releases were Rel-4 through Rel-7. Rel-8 was the start of 4G/LTE but 3G continued to evolve in this and later releases.

    Rel-5 introduced High Speed Downlink Packet Access (HSDPA) that supported shared channel transmission, HARQ and higher-order modulations. HSDPA brought lower latency, higher data rate and higher capacity. Rel-6 introduced Enhanced Uplink, aka High Speed Uplink Packet Access (HSUPA), with benefits and techniques somewhat similar to HSDPA. HSDPA and HSUPA are often together called HSPA.

    HSPA evolved to Rel-7 with MIMO and higher-older modulations. This was called HSPA+. From Rel-8, HSPA+ started supporting Carrier Aggregation (CA). Rel-11 marked the start of HSPA+ Advanced with the Multiflow feature. Rel-12 introduced HetNets and Wi-Fi interworking.

    The names 3.5G (HSPA), 3.75G (HSPA+) and 3.9G (LTE) are sometimes used, although this usage is not consistent across the industry.

  • Which are the main 4G releases?
    Main LTE releases. Source: Qualcomm, via Remmert 2021.
    Main LTE releases. Source: Qualcomm, via Remmert 2021.

    The first 4G/LTE release was Rel-8. It's main features were OFDMA waveform, FDD/TDD operation and an all-IP core network. Rel-9 added femtocells in the form of Home eNodeB (HeNB), Location Services (LCS), Evolved Multimedia Broadcast/Multicast Service (eMBMS), VoLTE and Circuit Switched FallBack (CSFB).

    Rel-10 introduced CA, HetNets and advanced MIMO. It marked the start of LTE Advanced. These features were further enhanced in Rel-11 and Rel-12.

    Rel-13 marked the start of LTE Advanced Pro with enhancements to CA and MIMO. The standard could achieve 1 Gbps in the downlink, giving rise to the term Gigabit LTE. It also introduced unlicensed access (LAA) and IoT (eMTC and NB-IoT). Enhancements to the specifications continued in Rel-14 and beyond.

  • Which are the main 5G releases?
    Main 5G releases. Source: Qualcomm, via Kinney 2022.
    Main 5G releases. Source: Qualcomm, via Kinney 2022.

    The first 5G release was Rel-15, launched in three phases: early drop with support for Non-Standalone (NSA) operation, main drop with support for Standalone (SA) operation, and late drop. Among its main features were mmWave band support, scalable OFDMA, Dual Connectivity (DC) with LTE, FDD/TDD support, short TTI, mini-slots, massive MIMO, beamforming, and more. The 5G Core (5GC) adopted a Service-Based Architecture (SBA) with network functions, microservices and APIs.

    Rel-16 enhanced MIMO, beamforming, DC/CA, UE power saving, positioning and Dynamic Spectrum Sharing (DSS). It also added new features: Integrated Access and Backhaul (IAB), operation in unlicensed spectrum, time-sensitive networking for industrial IoT, NR sidelink for Vehicle-to-Everything (V2X) communications, and more. Apart from many enhancements, Rel-17 added 60 GHz unlicensed band support, satellite communications and sidelink relaying.

    Rel-18 marks the start of 5G Advanced meant to enhance MIMO, mobility, AI-based decisions, sidelink, positioning, satellite communications, multicast, DSS, multi-SIM, and more.

Milestones

Dec
1998

The 3GPP Partnership Project Agreement is signed by five Organizational Partners: ARIB (Japan), ETSI (Europe), ATIS Committee T1 (USA), TTA (South Korea) and TTC (Japan). Their goal is to produce the 3G specifications. Subsequently, they expand their scope of work to include GSM/GPRS/EDGE specifications (since 2000) and evolution of 3G (since 2007).

2000
Evolution of 3G from Release 99 to Rel-7 and beyond. Source: Klug 2011.
Evolution of 3G from Release 99 to Rel-7 and beyond. Source: Klug 2011.

Release 99 for UMTS/3G is launched. It evolves to Rel-4 (2001).

2002
Evolution of HSPA. Source: Qualcomm 2014, slide 4.
Evolution of HSPA. Source: Qualcomm 2014, slide 4.

Rel-5 comes out. It's the first release of High Speed Packet Access (HSPA). Also part of HSPA is Rel-6 (2004). This further evolves to HSPA+ in Rel-7 (2007), Rel-8 (2008), Rel-9 (2009), and Rel-10 (2011). The next evolution is HSPA+ Advanced in Rel-12 (2015) and Rel-13 (2016). The slightly different dates in the figure reflect dates of commercial deployment.

2008
Evolution of LTE. Source: Qualcomm 2016.
Evolution of LTE. Source: Qualcomm 2016.

With Rel-8, the first release of 4G/LTE is launched. The LTE project work was started in December 2004. Originally named Evolved Universal Terrestrial Radio Access (E-UTRA) for the radio access part, it becomes significantly different from the UMTS system. LTE evolves to LTE Advanced in Rel-10 (2011), Rel-11 (2012) and Rel-12 (2015). This evolves to LTE Advanced Pro in Rel-13 (2016) and Rel-14 (2017). The slightly different dates in the figure reflect dates of commercial deployment.

2018
Evolution of 5G. Source: Rahman et al. 2021.
Evolution of 5G. Source: Rahman et al. 2021.

Rel-15, the first release of 5G, comes out in 2018, although an "early drop" occurred in December 2017. This is followed by Rel-16 (2020) and Rel-17 (2022). This evolves to 5G Advanced in Rel-18, which is expected in 2023.

2027

The first release of 6G, in Rel-21, is expected in 2027.

References

  1. 3GPP. 2022a. "Releases." Portal, 3GPP. Accessed 2022-10-18.
  2. 3GPP. 2022b. "File Name Conventions." 3GPP. Accessed 2022-10-19.
  3. 3GPP. 2022c. "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Technical Specification Group working methods (Release 18)." V18.0.1, September. Accessed 2022-10-19.
  4. 3GPP. 2022d. "Releases." 3GPP. Accessed 2022-10-22.
  5. 3GPP. 2022e. "The 5G Standard: Release 18." Poster, 3GPP, October. Accessed 2022-10-18.
  6. 3GPP. 2022f. "Introducing 3GPP." 3GPP. Accessed 2022-10-18.
  7. 3GPP. 2022g. "3GPP FAQ's." 3GPP. Accessed 2022-10-18.
  8. 3GPP. 2022h. "Change Requests." 3GPP. Accessed 2022-10-18.
  9. 3GPP. 2022i. "Third Generation Partnership Project Agreement." Until Annex 44. Updated 2022-04-27. Accessed 2022-10-19.
  10. Brydon, Alastair. 2012. "Summary of 3GPP Standards Releases for LTE." Unwired Insight, October 5. Accessed 2022-10-22.
  11. Casaccia, Lorenzo. 2017. "Understanding 3GPP – starting with the basics." OnQ Blog, Qualcomm, August 2. Accessed 2022-10-18.
  12. Dahlman, E., S. Parkvall, J. Sköld and P. Beming. 2008. "3G Evolution HSPA and LTE for Mobile Broadband." Second Edition, Academic Press, Elsevier Ltd. Accessed 2022-10-22.
  13. Dano, Mike. 2019. "Another set of 5G standards was just released, but no one really cares." LightReading, April 5. Accessed 2022-10-22.
  14. ETSI. 2022. "4th Generation (LTE)." ETSI. Accessed 2022-10-22.
  15. Ericsson. 2018. "5G Core (5GC) network: Get to the core of 5G." Ericsson, July 30. Accessed 2022-10-22.
  16. Ghadialy, Zahid. 2007. "3G -> 3.9G." The 3G4G Blog, May 31. Accessed 2022-10-22.
  17. Ghadialy, Zahid. 2017. "RRC states in 5G." The 3G4G Blog, November 5. Accessed 2022-10-22.
  18. Grigorik, Ilya. 2013. "Chapter 7. Mobile Networks." In: High Performance Browser Networking, O'Reilly Media. Accessed 2022-10-22.
  19. Kinney, Sean. 2022. "What will be included in 5G Advanced Release 18?" RCR Wireless News, January 13. Accessed 2022-10-22.
  20. Klug, Brian. 2011. "The iPhone 4S, HSPA+, and When HSPA+ is Real 4G." AnandTech, October 9. Accessed 2022-10-22.
  21. Meredith, J.M. 2002. "The change control cycle." Slides, May 17. Accessed 2022-10-22.
  22. Moniem-Tech. 2021. "5G New Radio (NR) Release 15 Technologies." Moniem-Tech, February 3. Accessed 2022-10-22.
  23. Montojo, Juan. 2021. "Setting off the 5G Advanced evolution." OnQ Blog, Qualcomm, December 10. Accessed 2022-10-22.
  24. ON5G. 2022. "The 3GPP sets the priorities for 5G Advanced, with specifications expected to be approved in 2024." Observatorio Nacional 5G, January 19. Accessed 2022-10-22.
  25. Peisa, Janne, Patrik Persson, Stefan Parkvall, Erik Dahlman, Asbjørn Grøvlen, Christian Hoymann, and Dirk Gerstenberger. 2020. "5G evolution: 3GPP releases 16 & 17 overview." Ericsson Technology Review, Ericsson, March 9. Accessed 2022-10-22.
  26. Qualcomm. 2014. "HSPA+ Evolution: Building upon the solid foundation." Slides, Qualcomm, August. Accessed 2022-10-22.
  27. Qualcomm. 2016. "Delivering on the LTE Advanced promise." Slides, Qualcomm, March. Accessed 2022-10-23.
  28. Rahman, Imadur, Sara Modarres Razavi, Olof Liberg, Christian Hoymann, Henning Wiemann, Claes Tidestav, Paul Schliwa-Bertling, Patrik Persson, and Dirk Gerstenberger. 2021. Ericsson Technology Review, Ericsson, October 13. Accessed 2022-10-23.
  29. Remmert, Harald. 2021. "What is LTE: How It Works and Why It Matters." Blog, Digi, November 19. Accessed 2022-10-22.
  30. Wikipedia. 2022. "3GPP." Wikipedia, September 24. Accessed 2022-10-23.

Further Reading

  1. Baron, J., K. Gupta, and B. Roberts. 2015. "Unpacking 3GPP Standards." March 24. Accessed 2022-10-22.
  2. Casaccia, Lorenzo. 2017. "Understanding 3GPP – starting with the basics." OnQ Blog, Qualcomm, August 2. Accessed 2022-10-18.
  3. Wikipedia. 2022. "3GPP." Wikipedia, September 24. Accessed 2022-10-23.
  4. 3GPP. 2022c. "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Technical Specification Group working methods (Release 18)." V18.0.1, September. Accessed 2022-10-19.

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Devopedia. 2022. "3GPP Release." Version 5, November 7. Accessed 2022-11-07. https://devopedia.org/3gpp-release
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