5G & 6G

5GSAprocedure.mp4

When you power ON your mobile phone, a series of processes take place to connect you to the network. Here’s a quick breakdown of what happens at the radio end:

Initial Access: Your phone performs a cell search and acquisition to sync with the target cell. The Primary Sync Signal (PSS) and Secondary Sync Signal (SSS) help establish this synchronization with the Downlink (DL).
Master Information Block (MIB): The MIB from NR (New Radio) provides your phone with the essential information to access the network. Think of it as getting the basic instructions needed to proceed!
System Information Block (SIB): This block in the DL contains key configurations, such as cell selection, re-selection, random access parameters, PLMN identity, and access class barring list. Once all criteria are met, your phone selects a cell to connect to.
Random Access Procedure: The initial access from your phone to NR begins here. The network decodes the preamble, and UL (Uplink) synchronization is performed.
Radio Resource Control (RRC) & NAS Signaling: An RRC is set up, followed by an initial NAS message, which establishes a signaling connection between your phone and the Access and Mobility Management Function (AMF) in the network.

Evolution of 3GPP 5G Network Slice

The concept of network slicing has been one of the standout features in 5G (no pun intended). It allows operators to offer logically isolated networks over shared infrastructure, each tailored for specific applications or services. These slices are identified using a combination of the Slice/Service Type (SST) and an optional Slice Differentiator (SD), together forming what is called a Single Network Slice Selection Assistance Information (S-NSSAI).To ensure global interoperability and support for roaming scenarios, 3GPP standardises a set of SST values. These are intended to provide common ground across public land mobile networks for the most prevalent slice types. Over the course of different 3GPP releases, the list of standardised SST values has grown to reflect emerging use cases and evolving requirements.

The foundation was laid in Release 15, where the first three SST values were introduced. SST 1 represents enhanced Mobile Broadband (eMBB), suitable for high throughput services like video streaming, large file downloads and augmented reality. SST 2 refers to Ultra-Reliable and Low-Latency Communications (URLLC), designed for time-sensitive applications such as factory automation, remote surgery and smart grids. SST 3 is for Massive Internet of Things (mIoT - earlier referred to as mMTC), tailored for large-scale deployments of low-power sensors in use cases such as smart metering and logistics.
The first major extension came with Release 16, which introduced SST 4 for Vehicle-to-Everything (V2X) services. This slice type addresses the requirements of connected vehicles, particularly in terms of ultra low latency, high reliability and localised communication. It was the first time a vertical-specific slice type was defined.
With Release 17, the slicing framework was extended further to include SST 5, defined for High-Performance Machine-Type Communications (HMTC). This slice is aimed at industrial automation and use cases that require highly deterministic and reliable communication patterns between machines. It enhances the original URLLC profile by refining it for industrial-grade requirements.
Recognising the growing importance of immersive services, Release 18 added SST 6, defined for High Data Rate and Low Latency Communications (HDLLC). This slice targets extended reality, cloud gaming and other applications that simultaneously demand low delay and high bandwidth. It goes beyond what enhanced Mobile Broadband or URLLC individually offer by addressing the combination of both extremes. The documentation refers to this as being suitable for extended reality and media services, underlining the increasing focus on immersive technologies and their networking needs.
Finally, Release 19 introduced SST 7 for Guaranteed Bit Rate Streaming Services (GBRSS). This new slice supports services where continuous, guaranteed throughput is essential. It is particularly relevant for live broadcasting, high-definition streaming, or virtual presence applications where quality cannot degrade over time.

This gradual and deliberate expansion of standardised SSTs highlights how 5G is not a one-size-fits-all solution. Instead, it is a dynamic platform that adapts to the needs of different industries. As use cases grow more sophisticated and diverse, having standardised slice types helps ensure compatibility, simplify device and network configuration, and promote innovation.It is also worth noting that these SST values are not mandatory for every operator to implement. A network can choose to support a subset based on its service strategy. For example, a public network may prioritise SSTs 1 and 3, while a private industrial deployment might focus on SST 5 or 7.With slicing increasingly central to how 5G will be "monetised" and deployed, expect this list to keep growing in future releases. Each new SST tells a story about where the telecoms ecosystem is heading.

6G Timeline:

ITU-R finished its initial phase setting the basis for the development of 6G, providing the new ITU-R Report on future technology trends [Dec. 2022] and the Recommendation on IMT-2030 (6G) Framework [Nov. 2023]. In the next phase starting from 2024, ITU-R will further define relevant technical performance requirements, evaluation methodologies, and submission templates for potential 6G radio interface technologies. After that, the evaluation process and completion of 6G specification will conclude by 2030.

ITU-R Report on future technology trends [ITU-R M.2516 Dec. 2022] details future technology trends for terrestrial IMT systems, specifically focusing on the timeframe up to 2030 and beyond, according to ITU. It covers key emerging services, applications, driving factors, and relevant aspects of radio interfaces, mobile terminals, and radio access networks for IMT-2030.
The ITU-R Recommendation on the IMT-2030 (6G) framework [ITU-R M.2160 Nov.2023] provides the foundation for the next generation of mobile technology. This framework identifies key capabilities and usage scenarios for 6G, including immersive communication, hyper-reliable and low-latency communication, enhanced ubiquitous connectivity, and massive communication, along with integrated multi-dimensional sensing. It also sets the stage for the development of 6G radio interface technologies and standards, with the goal of achieving global alignment on 6G by 2030.

We expect 3GPP will begin its initial technology study for 6G from R20, and R21 is expected to be the 1st set of 6G technical specifications. 3GPP have conducts a study on 6G use cases and requirements [3GPP TR 22.870 Study on 6G Use Cases and Service Requirements] before the start of the technology studies, anticipating an overlapping period between the two activities.

3GPP TR 22.870 Study on 6G Use Cases and Service Requirements v3.0 [March 2025] is a study focusing on the use cases and service requirements for 6G. It's a crucial step in defining the foundation for future 6G systems by exploring next-generation service demands and cutting-edge use cases. This study, part of 3GPP Release 20, lays the groundwork for the 6G standard, with the first version expected to be finalized in 2029 and commercialization in 2030.
In December 12 2024, 3GPP initiated 6G studies, focusing on defining requirements for networks beyond 2030 and aligning with the ITU-R's IMT-2030 framework. This involved discussions on data rate, latency, and reliability, aiming to support applications like augmented reality and remote driving. 3GPP also shared its workplan with the ITU-R, seeking global consensus for 6G. During Technical Specification Group RAN’s meeting RAN#106, in Madrid, an important 6G study item was approved. The study represents a significant milestone in 3GPP’s interactions with ITU on 6G technical performance requirements (TPRs) as future, deployment scenarios, requirements and potential directions of 6G radio access technologies are further identified and investigated in 3GPP. The 3GPP study item (Details in RP-243327) aims to investigate a candidate set of items for minimum TPRs based on the Recommendation ITU-R M.2160 and, where applicable, the associated target values and key assumptions for the identified minimum TPRs.
In March 10 - 11 2025, 3GPP 6G Workshop in Incheon, South Korea, was chaired by the leadership of the three Technical Specification Groups : TSG SA, TSG RAN and TSG CT. The workshop brought together industry experts, vendors, operators, and academics to share their visions for the next generation of mobile networks. With 603 in-person attendees, 1,676 registrations, and 243 documents submitted, it was a significant step towards shaping the early foundations of 6G. The workshop highlighted several compelling motivations for 6G, all aimed at pushing networks beyond traditional communication services. To achieve the ambitious vision laid out for 6G, the workshop defined several core goals. The transition from 5G to 6G will be shaped by the industry's experience with 5G deployments. The workshop identified several lessons to apply moving forward. The workshop explored several technical areas that could shape 6G. The workshop also laid out a clear workplan for 6G:

Release 20: Early 6G studies will begin in June 2025, focusing on both ITU-oriented and general RAN studies.Release 21: The first official 6G specifications are expected in Release 21, targeted for submission to IMT-2030. This release will define the technical requirements and form the foundation of 6G.Timeline: The first technical specifications are expected by 2030, with a single code freeze (in terms of ASN.1 and open API freeze) planned for March 2029.

In 9 - 13 June 2025 3GPP plenaries #108 Prague, Czech Republic, Release-20 officially launches the 6G technical Study Item, and the 3GPP companies have agreed on several key study objectives. Following extensive discussions and negotiations in both online and offline sessions, the 6GR study scope has been agreed upon to encompass key areas of foundational wireless technology design. As we officially set the scope for 3GPP Release 20, encompassing both 5G Advanced and 6G, the road ahead is filled with exciting challenges and opportunities. For 6G, we anticipate the study item to kick off in the physical layer working group (RAN1) in August followed by other working groups later in the year.

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