Prof. Ted Rappaport Keynote at EuCNC & 6G Summit 2023 on 'Looking Towards the 6G Era - What we may expect, and why'

Prof. Ted Rappaport has featured a few times in our blog posts (see here and here). Today we look at his recent keynote at the EuCNC & 6G Summit 2023 on the topic 'Looking Towards the 6G Era - What we may expect, and why'. The abstract of the talk says:

Recent work has shown that the fundamentals of the radio propagation channel will enable mobile communications all the way to 900 GHz, offering bandwidths of tens of GHz. An amazing fact that is all but disregarded is that the three fundamental technological breakthroughs of 5G, namely millimeter wave technology, small cell densification, and massive multiple-input multiple-output (massive-MIMO) antenna systems, are paving the way for the next several decades of the wireless industry. This talk demonstrates how the 5G era will futureproof wireless networks as we enter the 6G era and beyond — an era of wireless cognition and human-style computing. In fewer than 20 years, wireless networks will carry information at the computation speed of the human brain. Yet, how will engineers ensure that we build these networks with sustainability and power efficiency in mind? This talk offers some solutions and promising areas of exploration to ensure the future 6G era is lightning fast yet kind to planet earth.

Next G Alliance has a nice short report looking at 'Terminology for Frequency Ranges'. Handy and useful charts - https://t.co/kfJFxcdUDo via @atisupdates @NextGAlliance #Free5Gtraining #3G4G5G #ATIS #NGA #5G #B5G #6G #Frequency #Spectrum #Bands #mmWave #cmWave #THz pic.twitter.com/Nyoh1X0asX

— Free 5G Training (@5Gtraining) July 25, 2023

Recently I had a discussion about mmWave, sub-THz, THz, etc. This chart in the Tweet above is handy with deciphering the 5G/6G spectrum terminology.

Prof. Rappaport covered quite a few topics on spectrum above 100 GHz and made a strong case for mmWave and Terahertz. The mmWave adoption for 5G hasn't yet taken off so we will have to see how enthusiastic the industry is for even higher frequencies. The other keynotes from the conference (see references below) argued for cmWave as the mid-band for 6G. We will have to wait and see where all this discussion goes.

The talk is embedded below:

Related Posts: 

• Free 6G Training: Recent Advances on Terahertz (THz) communications
• The 3G4G Blog - 6G: Above 100 GHz and Terahertz (THz) Frequencies
• The 3G4G Blog: Spectrum for 5G NR beyond 52.6 GHz
• Free 6G Training: Ericsson's Keynote at EuCNC & 6G Summit 2023 on '6G – Connecting a cyber-physical world'
• Free 6G Training: Nokia's and Docomo's Joint Keynote at EuCNC & 6G Summit 2023 on '6G getting into next gear'
• Free 6G Training: Huawei's Keynote at EuCNC & 6G Summit 2023 on 'On the Convergence Route for 6G'
• Free 6G Training: EuCNC & 6G Summit 2023 Panel Session on 'Sustainability challenges and opportunities for 6G'
• Free 6G Training: Samsung's 6G Spectrum Whitepaper Discusses Candidate Bands
• Free 6G Training: Do we need more Bandwidth or Higher Bandwidth Efficiency?
• Free 6G Training: 7 Defining Features of Terahertz (THz) Wireless Communications Systems 

New 5G NTN Spectrum Bands in FR1 and FR2

Release-17 includes two new FR1 bands for NTN; n255 (a.k.a. NTN 1.6GHz) and n256 (a.k.a. NTN 2GHz). The picture is from a slide in Rohde & Schwarz presentation available here. Quoting from an article by Reiner Stuhlfauth, Technology Manager Wireless, Rohde & Schwarz:

Currently, several frequency ranges are being discussed within 3GPP for NTN. Some are in the FR1 legacy spectrum, and some beyond 10 GHz and FR2. The current FR1 bands discussed for NTN are:

• The S-band frequencies from 1980 to 2010 MHz in uplink (UL) direction and from 2170 to 2200 MHz in downlink (DL) direction (Band n256).
• The L-band frequencies from 1525 to 1559 MHz DL together with 1626.5 to 1660.5 MHz for the UL (Band n255).1

These frequency ranges have lower path attenuation, and they’re already used in legacy communications. Thus, components are available now, but the bands are very crowded, and the usable bandwidth is restricted. Current maximum bandwidth is 20 MHz with up to 40-MHz overall bandwidth envisaged in the future [TR 38.811].

As far as long-term NTN spectrum use is concerned, 3GPP is discussing NR-NTN above 10 GHz. The Ka-band is the highest-priority band with uplinks between 17.7 and 20.2 GHz and downlinks between 27.5 and 30 GHz, based on ITU information regarding satellite communications frequency use.2 Among current FR2 challenges, one is that some of the discussed bands fall into the spectrum gap between FR1 and FR2 and that NTN frequencies will use FDD duplex mode due to the long roundtrip time.

6G Unified networks: Multi-Layer Multi-Dimension Multi-Band (ML-MD-MB) Topology via @RohdeSchwarz highlights the future 6G Satellite and Terrestrial Network Convergence Vision#3G4G5G #5G #B5G #6G #NTN pic.twitter.com/DHVIP9kw8J

— Zahid Ghadialy (@zahidtg) May 20, 2023

Worth highlighting again that the bands above, including n510, n511 and n512 are all FDD bands due to the long round trip times.

The latest issue of 3GPP highlight magazine has an article on NTN as well. Quoting from the article:

The NTN standard completed as part of 3GPP Release 17 defines key enhancements to support satellite networks for two types of radio protocols/interfaces:

• 5G NR radio interface family also known as NR-NTN
• 4G NB-IoT & eMTC radio interfaces family known as IoT-NTN

These critical enhancements including adaptation for satellite latency and doppler effects have been carefully defined to support a wide range of satellite network deployment scenarios and orbits (i.e., LEO, MEO and GEO), terminal types (handheld, IoT, vehicle mounted), frequency bands, beam types (Earth fixed/Earth moving) and sizes. The NTN standard also addresses mobility procedures across both terrestrial and non-terrestrial network components. Release 17 further includes Radio Frequency and Radio Resource Management specifications for terminals and satellite access nodes operating in two FR1 frequency ranges allocated to Mobile Satellite Services (i.e., n255 and n256).

You can read it here.

Related Posts: 

• The 3G4G Blog: 3GPP 5G Non Terrestrial Networks (NTN) Standardization Update
• Connectivity Technology Blog: 5G NR-NTN Demos make a Debut at MWC 2023
• Connectivity Technology Blog: Direct-to-Mobile Communications Using LEO Satellites gets a Step Closer
• Connectivity Technology Blog: TIP has launched 'Non-Terrestrial Connectivity Solutions' Group
• The 3G4G Blog: An Introduction to Non-Terrestrial Networks (NTN)
• Free 6G Training: Non-Terrestrial Networks (NTN) & Satellites - Taking 6G to the Stars
• The 3G4G Blog: How Many People are Still Unconnected in 2023 and Why? 

Qualcomm Explains 5G Millimeter Wave (mmWave) Future & Integrated Access and Backhaul (IAB)

We have covered various topics in our blog posts on millimeter wave spectrum and even going beyond 52.6 GHz in FR2. A Qualcomm webinar from back in January expands on many of the topics that I looked superficially in various posts (links at the bottom).

The following is edited from the Qualcomm blog post:

5G NR in unlicensed spectrum (NR-U) was standardized in Release 16 and it is a key enabler for the 5G expansion to new use cases and verticals, providing expanded spectrum access to mobile operators, service providers, and industry players. At the same time, we are starting to push the mmWave boundary to even higher bands toward the sub-Terahertz (i.e., >100 GHz) range. Expected in Release 17, 5G NR will support spectrum bands up to 71 GHz, leveraging the 5G NR Release 15 scalable numerology and flexible framework. This opens up 5G to operate in the globally unlicensed 60 GHz band, which can fuel a broad range of new applications and deployments.

One daunting challenge that mobile operators will face when expanding 5G mmWave network coverage is the cost of deploying additional base stations for mmWave, which usually requires new fiber optics backhaul installations. Release 16-defined IAB allows a base station to not just provide wireless access for its user devices (e.g., smartphones) but also the ability to backhaul wirelessly via neighboring base stations using the same mmWave spectrum. IAB opens the door to more flexible densification strategies, allowing mobile operators to quickly add new base stations to their networks before having to install new fiber to increase backhaul capacity. 

Release 16 established foundational IAB capabilities, such as dynamic topology adaptation for load balancing and blockage mitigation, and Release 17+ will further enhance IAB by bringing new features like full-duplex operation, topology redundancy, and ML-based network management.

Beyond IAB, there is a rich roadmap of other new features that can further improve 5G mmWave system performance and efficiency. The webinar embedded below is presented by Ozge Koymen, Senior Director, Technology, Qualcomm Technologies, Inc. It covers the following topics:

• Qualcomm's vision for 5G mmWave and the new opportunities it poises to bring for the broader ecosystem
• mmWave capabilities and enhancements coming in Release -16 and beyond
• Qualcomm’s role in mobilizing and democratizing 5G mmWave to usher in new experiences
• Latest update on the global commercial rollout of 5G mmWave networks and devices

Slides of the presentation are available here.

Related Posts:

• Free 6G Training: Spectrum for 5G, Beyond 5G and 6G research
• The 3G4G Blog: A mmWave Special Cell in Open RAN Environment
• The 3G4G Blog: Spectrum for 5G NR beyond 52.6 GHz
• The 3G4G Blog: 5G Integrated Access and Backhaul (IAB) Enhancements in Rel-17
• The 3G4G Blog: Carrier Aggregation (CA) and Dual Connectivity (DC)
• The 3G4G Blog: The Politics of Standalone vs Non-Standalone 5G & 4G Speeds 

A mmWave Special Cell in Open RAN Environment

NR RRC signaling messages exchanged for establishing a 5G radio connection, in particular the NR RRC Reconfiguration and NR RRC CG Config messages, contain a parameter called "SpCellID", which refers to the Special Cell ID. 

The concept of the Special Cell already exists in 3GPP LTE Advanced standards. Here a Special Cell is set of physical cells with same or different carrier frequency and physical cell ID (PCI) that overlap in a certain geographical area and thus, are combined for data transmission to/from UEs located in this area.

This concept now also gains high importance for 5G NR mmWave spectrum and here is why:

Many 5G mmWave radio transmitters can only handle a maximum bandwidth of 100 MHz, but the radio sector shall be covered with total bandwidth of e.g. 600 MHz. To achieve this six mmWave radio transmitters are installed in parallel at the same spot covering the same footprint. 

Each transmitter is identified on the radio interface by its own dedicated NR ARFCN (carrier frequency) and PCI. Thus, from UE point of view the sector is covered with 6 dedicated NR cells that all together form a Special Cell.

When a UE gets radio resources assigned in this 5G sector one of  the 6 cells is the Primary Cell, which NR CGI (Cell Global Identity) is then used as Special Cell ID in layer 3 signaling messages. All other cells act as Secondary Cells.

In an Open RAN environment the F1AP protocol allows perfect analysis of the SpCell resource allocation since it contains the SpCellID as well as all SCellIDs to be setup in the call. 

If the gNB-DU fails to allocated resources for a particular Secondary Cell this will also be signaled together with a failure cause value on F1AP as illustrated in the figure below. Also radio link failures occurring within the Special Cell will be signaled on F1AP including a cause value that provides deeper insight than  protocol causes seen on X2AP (in case of 5G NSA connections) or NGAP (in case of 5G SA connections). 

(click on image to enlarge)