Mobile Network Architecture: How did we get here & where should we go?

Lorenzo Casaccia, Vice President of Technical Standards, IP Qualcomm Europe, Inc. has been with Qualcomm since 2000. During that time he's had a variety of roles related to wireless communication, including research and system design, regulatory aspects, product management, and technical standardization. He currently leads a team of engineers across three continents driving Qualcomm’s activities in 3GPP, the standards body designing technologies for 4G and 5G.

Couple of his well known articles on Qualcomm OnQ Blog on 'Counting 3GPP contributions' and 'ETSI SEP database manipulations' are available here and here respectively.

Fascinating & rather heretical presentation by @Qualcomm on the 6G Core workshop - suggesting that maybe a new architecture is needed that massively reduces role/complexity of the core

Is most slicing-skeptic I’ve seen from a big vendor

(Sorry don’t have screenshots)

— Dean Bubley (@disruptivedean) September 12, 2023

At the recent NIST/IEEE Future Networks 6G Core Networks Workshop he was able to bring in his experience to deliver a fantastic talk looking at how the mobile network architecture has diverged from the Data Networks (Internet) architecture and how this has limited innovation in the mobile networks.

He concludes by providing a solution on how to fix this network architecture in 6G by limiting any new services going in the control plane as well as ensuring over the time all services move to the user plane. The control plane will then stop being 'G' specific which will benefit the network innovation in the long term. 

There is no provision to embed the video so please look at the top of the page here. Lorenzo's talk starts at 03:03:50. The Q&A session for the panel starts at 03:53:20 for anyone interested.

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• Free 6G Training: SK Telecom Claims ‘Bare Metal-Based Cloud-Native 5G Core’ as Foundation for 6G Evolution
• The 3G4G Blog: CUPS for Flexible U-Plane Processing Based on Traffic Characteristics
• Free 6G Training: Design aspects for emerging 6G Organic Core Networks
• The 3G4G Blog: IP Multimedia Subsystem (IMS) Support for Service Based Architecture (SBA)
• Free 6G Training: China Mobile's view of how to define a 6G Network
• The 3G4G Blog: Three New Standards to Accelerate 5G Wireless Wireline Convergence (WWC) 

The Digital Railway supported by FRMCS

As discussed in our earlier post, the long-standing 2G cellular standard for rail communication, known as the Global System for Mobile Communications–Railway (GSM–R), remains in use across Europe, China, India, Africa, and Australia. However, software and hardware vendors predict that this early digital cellular technology will start to be phased out in 2025, as a new 5G-based system specifically for railway applications is expected to be introduced.

According to the European Union Agency for Railways (ERA), GSM–R supports communication between train drivers and traffic control centres with features such as group communication, location-dependent addressing, priority levels, railway emergency calls, and shunting communication. This system enables data transmission between trains and control centres at speeds exceeding 300 mph.

Yet, GSM–R is beginning to show its age. While it is adequate for basic voice communication, its 4 MHz bandwidth, which supports multiple 200 KHz channels, limits its functionality. Downlink communications use the 876–880 MHz range, while the uplink operates at 921–925 MHz.

The maximum data transmission rate for GSM–R is just 9.6 kbit/s, making it unsuitable for real-time data communication. Its capabilities are essentially limited to sending SMS text messages, with little capacity for anything more advanced.

The Future Railway Mobile Communication System (FRMCS), a 5G-based successor to GSM–R, will provide both voice and data services for railway communications. The FRMCS project is being led by the International Union of Railways (UIC) in collaboration with major rail infrastructure companies and telecom solution providers. It is set to be based on the 5G 3GPP standard, meaning it will not require a railway-specific cellular network technology.

FRMCS, which will use the standalone 5G NR specification, is expected to be finalised by the end of 2022. This new standard will operate on harmonised frequencies at 900 MHz and 1900 MHz to ensure interoperability for rail command and control systems as they transition from GSM–R to FRMCS.

This seems questionable from @SNCFVoyageurs

Asserts that train operational comms is mostly uplink & user connectivity downlink, so OK to share FDD public networks

Hmm. Growing use of uplink data from public usage, often with low latency needs pic.twitter.com/JNxHVJvaNL

— Dean Bubley (@disruptivedean) November 14, 2023

Mobile network operators will also be able to offer 5G connectivity for train passengers, collaborating with railway companies to provide the high-bandwidth digital services needed to streamline modern train operations.

Currently, many rail operators offer Wi-Fi onboard or install repeaters to enhance mobile network coverage within carriages. However, these solutions can be costly to maintain and upgrade, and repeated signals can cause interference when train doors open. An alternative solution is for public mobile operators to provide passenger connectivity through their existing 5G networks, with additional 5G towers placed along major rail lines.

To improve 5G signal penetration, train windows can be fitted with special “5G-friendly” glass, which allows signals to pass through more easily (standard window glass is often coated to reduce solar radiation inside the carriage). This approach reduces the need for expensive Wi-Fi and repeater systems, enabling mobile operators to deliver high-speed broadband services to passengers more efficiently.

In their webinar last year, Wray Castle stated that FRMCS is not simply a replacement for GSM-R nor is it a single specific technology. In fact, UIC have stated that FRMCS is technology agnostic. The webinar discussed:

• What is FRMCS and how does it differ from GSM-R?
• How soon will railways be replacing GSM-R?
• Is there a migration strategy?
• Do we have sufficient radio spectrum?
• What is the most probable technology that will be used?

The video of that is embedded below:

Wray Castle also conducts regular courses on this topic. Details here.

Related Posts:

• The 3G4G Blog: Future Railway Mobile Communication System (FRMCS)
• Connectivity Technology Blog: Future Spectrum Demand for Rail Communications
• Connectivity Technology Blog: 'Gigabit Innovation Track' (GINT) Gets Green Light in Germany 

Presentations from 2nd IEEE Open RAN Summit

The second IEEE SA (Standards Association) Open RAN summit, hosted by the Johns Hopkins University Applied Physics Lab, took place on 9-10 Aug 2023. It covered the topics related to the standardization of Open RAN including O-RAN Alliance, 3GPP, IEEE, various deployment scenarios, testing and integration, Open RAN security, RAN slicing, and RAN optimization among others. 

The videos of the presentations can be viewed on the summit page here or though the video playlist here.

The talk from Dr. Chih-Lin I, O-RAN Alliance TSC Co-Chair and CMCC Chief Scientist, Wireless Technologies on 'AI/ML impact, from 5.5G to 6G' is embedded below:

Related Posts: 

• The 3G4G Blog: Open RAN Terminology and Players
• The 3G4G Blog: O-RAN Introduction for Beginners
• The 3G4G Blog: Accelerating O-RAN Adoption Through Open Source
• The 3G4G Blog: 5G RAN Functional Splits
• The 3G4G Blog: Open RAN Explanation, Videos, White papers and Other Resources