Showing posts with label Nokia Networks. Show all posts
Showing posts with label Nokia Networks. Show all posts

Wednesday 21 June 2023

3GPP TSG RAN and TSG SA Release-19 Workshop Summary

3GPP recently announced the milestone of reaching 100th plenaries of the three Technical Specification Groups (TSGs) in 3GPP which took place in Taipei last week. If you are unsure what TSGs are, we recently made a tutorial of 3GPP, available here.

During the plenary TSG SA and TSG RAN held workshops on Release 19. The top level link for RAN workshop is here while that for SA is here. SA also has HTML link of the documents here.

The slide above is from the RAN chair's summary provides list of topics that were discussed. The following is the executive summary from the draft workshop report:

The 3GPP TSG RAN Rel-19 face-to-face workshop was held June 15 - June 16, 2023 in Taipei hosted by TAICS (Taiwan Association of Information and Communication Standards) and MediaTek with 174 participants (see Annex A) and 491 Tdocs (see Annex B). A GotoWebinar conference call was carried out during the whole workshop to display discussed documents and to allow listen & talk access for people joining remotely.

The workshop agenda was provided in RWS-230001 and split into 3 main parts:

  • High-level overview proposals for Rel-19: 18 Tdocs handled, 46 not treated, 1 in the end endorsed (RP-230488)
  • Specific RAN1/2/3-led Rel-19 topics: 29 Tdocs handled, 369 not treated
  • RAN4-led Rel-19 topics (for information only): 20 not treated

Note: High-level overview proposals for Rel-19 and RAN4-led Rel-19 topics had the restriction of maximum one contribution led per company.

Some guidance about the workshop was provided on the RAN email reflector on 28.04.23 and 02.05.23.

Time plan versions of the workshop were provided on 02.05.23, 11.06.23 and on 15.06.23.

Workshop inputs were possible from 28.04.23 until the submission deadline 31.05.23 9pm UTC.

(Late Tdoc requests as well as revisions of Tdocs after the Tdoc request deadline 30.05.23 9pm UTC were avoided in order to not complicate the Tdoc handling, like quotas for AI 4 and 6, preparations of the workshop in parallel to RAN #100 and preparations of the summary etc.)

Originally, Thursday 15.06.23 and Friday 16.06.23 morning were planned for presentations of a limited set of 47 workshop contributions (selected by the RAN chair trying to achieve a fair coverage of the topics and interests and taking into account that there were many more inputs that can be handled in a 2 days workshop) and Friday afternoon was reserved for the discussion of a summary of the RAN chair (in RWS-230488). Note: Since the presentation part went faster and the Friday lunch break was skipped, the workshop ended on Friday afternoon earlier than originally planned.

Finally, the RAN chair's summary in RWS-230488 was endorsed indicating the motivations and handling of the workshop, the Rel-19 timeline and load plans and the management and categorization of topics.

TSG SA didn't have a summary slide but SWS-230002, output of drafting session on Consolidated SA WG2 Rel-19 Work, listed the following topics:

  • Satellite Architecure Enhancements
  • XRM Enhancements and Metaverse
  • AI/ML enhancements
  • Multi-access (Dual 3GPP + ATSSS Enh)
  • Integrated Sensing and Communication
  • Ambient IoT
  • Energy Efficiency / Energy Saving as a Service
  • IMS and NG_RTC enhancements
  • Edge Computing Enhancements
  • Proximity Services enhancements 
  • TSC/URLLC/TRS enhancements 
  • Network Sharing 
  • User identities + identification of device behind RG/AP
  • 5G Femto 
  • UAS enhancements 
  • VMR Enhancements 
  • UPEAS Enhancements 

Fattesinh Deshmukh has a summary of 3GPP RAN Rel-19 Workshop on LinkedIn here. Nokia has their summary of the workshop here.

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Tuesday 22 November 2022

Preparing for Metaverse-Ready Networks

Metaverse means different things for different people. If you explain Metaverse with an example, many people understand but they are generally looking at things from a different point of view. A bit like blind men and an elephant. Similarly when we talk about Metaverse-ready networks, it can mean different things to different people, depending on their background.

Back in Oct 2021, Facebook changed its name to Meta with a vision to bring the metaverse to life and help people connect, find communities and grow businesses. This was followed by a blog post by Dan Rabinovitsj, Vice President, Meta Connectivity, highlighting the high-level requirements for these metaverse-ready networks. 

At Fyuz 2022, the Telecom Infra Project (TIP) announced the launch of Metaverse-Ready Networks Project Group primary whose objective is to accelerate the development of solutions and architectures that enhance network readiness to support metaverse experiences. Meta Platforms, Microsoft, Sparkle, T-Mobile and Telefónica are the initial co-chairs of this Project Group.

Cambridge Wireless' CWIC 2022 discussed 'The Hyperconnected Human'. One of the sessions focussed on 'Living in the Metaverse' which I think was just brilliant. The slides are available from the event page and the video is embedded below:

Coming back to metaverse-ready networks, the final day of Fyuz 2022 conference featured 'The Meta Connectivity Summit' produced by Meta. 

The main stage featured a lot of interesting panel sessions looking at metaverse use cases and applications, technology ecosystem, operator perspectives as well as a talk by CIO of Softbank. The sessions are embedded below. The breakout sessions were not shared. 

Metaverse is also being used as a catch-all for use cases and applications in 6G. While many of the requirements of Metaverse will be met by 5G and beyond applications, 6G will bring in even more extreme requirements which would justify the investments in the Metaverse-Ready Networks.

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Monday 22 August 2022

DCCA Features and Enhancements in 5G New Radio

In another new whitepaper on 5G-Advanced, Nokia has detailed DCCA (DC + CA) features and enhancements from Rel-15 until Rel-18. The following is an extract from the paper:

Mobility is one of the essential components of 5G-Advanced. 3GPP has already defined a set of functionalities and features that will be a part of the 5G-Advanced Release 18 package. These functionalities can be grouped into four areas: providing new levels of experience, network extension into new areas, mobile network expansion beyond connectivity, and providing operational support excellence. Mobility enhancements in Release 18 will be an important part of the ‘Experience enhancements” block of features, with the goal of reducing interruption time and improving mobility robustness.

Fig. 2 shows a high-level schematic of mobility and dual connectivity (DC)/Carrier Aggregation (CA) related mechanisms that are introduced in the different 5G legacy releases towards 5G-Advanced in Release 18. Innovations such as Conditional Handover (CHO) and dual active protocol stack (DAPS) are introduced in Release 16. More efficient operation of carrier aggregation (CA), dual connectivity (DC), and the combination of those denoted as DCCA, as well as Multi-Radio Access Technology DC (MR-DC) are introduced through Releases 16 and 17.

For harvesting the full benefits of CA/DC techniques, it is important to have an agile framework where secondary cell(s) are timely identified and configured to the UE when needed. This is of importance for non-standalone (NSA) deployments where a carrier on NR should be quickly configured and activated to take advantage of 5G. Similarly, it is of importance for standalone (SA) cases where e.g. a UE with its Primary Cell (PCell) on NR Frequency Range 1 (FR1) wants to take additional carriers, either on FR1 and/or FR2 bands, into use. Thus, there is a need to support cases where the aggregated carriers are either from the same or difference sites. The management of such additional carriers for a UE shall be highly agile in line with the user traffic and QoS demands; quickly enabling usage of additional carriers when needed and again quickly released when no longer demanded to avoid unnecessary processing at the UE and to reduce its energy consumption. This is of particular importance for users with time-varying traffic demands (aka burst traffic conditions).

In the following, we describe how such carrier management is gradually improved by introducing enhancements for cell identification, RRM measurements and reduced reporting delays from UEs. As well as innovations related to Conditional PSCell Addition and Change (CPAC) and deactivation of secondary cell groups are outlined.

The paper goes on to discuss the following scenarios in detail for DCCA enhancements:

  • Early measurement reporting
  • Secondary cell (SCell) activation time improvements
    • Direct SCell activation
    • Temporary RS (TRS)-based SCell Activation
  • Conditional Secondary Node (SN) addition and change for fast access
  • Activation of secondary cell group

The table below summarizes the DCCA features in 5G NR

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Tuesday 25 January 2022

3GPP Release-18 Work Moves Into Focus as Release-17 Reaches Maturity

In early December 2021, 3GPP reached a consensus on the scope of 5G NR Release-18. With the 3GPP Rel-17 functional freeze set for March 2022, Release-18 work is moving into focus. This is being billed as a significant milestone marking the beginning of 5G Advanced — the second wave of wireless innovations that will fulfil the 5G vision. Release 18 is expected to build on the solid foundation set by 3GPP Releases 15, 16, and 17, and it sets the longer-term evolution direction of 5G and beyond.

(click on the image to enlarge - PDF here)

The 3GPP Release-18 page has a concise summary of all that you need to know, including the timeline. For anyone interested in going through features one-by-one, start navigating from here, select Rel-18 from the top.

For others who may be more interested in summary rather than a lot of details, here are some good links to navigate:

  • Nokia whitepaper - 5G-Advanced: Expanding 5G for the connected world (link)
  • Paper by Ericsson researcher, Xingqin Lin, 'An Overview of 5G Advanced Evolution in 3GPP Release 18' (link)
  • Marcin Dryjański, Rimedo Labs - 3GPP Rel-18: 5G-Advanced RAN Features (link)
  • Bevin Fletcher, FierceWireless: Next 3GPP standard tees up 5G Advanced (link)

As always, Qualcomm has a fantastic summary of 5G evolution and features in 3GPP Release-18 on their page here. The image above nicely shows the evolution of 5G from Release-15 all the way to Release-18. The image below shows a summary of 3GPP Release-18, 5G-Advanced features.

They also hosted a webinar with RCR wireless. The webinar is embedded below.

The slides can be downloaded from GSA website (account required, free to register) here.

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Tuesday 24 August 2021

3GPP's 5G-Advanced Technology Evolution from a Network Perspective Whitepaper


China Mobile, along with a bunch of other organizations including China Unicom, China Telecom, CAICT, Huawei, Nokia, Ericsson, etc., produced a white paper on what technology evolutions will we see as part of 5G-Advanced. This comes not so long after the 3GPP 5G-Advanced Workshop which a blogged about here.

The abstract of the whitepaper says:

The commercialization of 5G networks is accelerating globally. From the perspective of industry development drivers, 5G communications are considered the key to personal consumption experience upgrades and digital industrial transformation. Major economies around the world require 5G to be an essential part of long-term industrial development. 5G will enter thousands of industries in terms of business, and technically, 5G needs to integrate DOICT (DT - Data Technology, OT - Operational Technology, IT - Information Technology and CT - Communication Technology) and other technologies further. Therefore, this white paper proposes that continuous research on the follow-up evolution of 5G networks—5G-Advanced is required, and full consideration of architecture evolution and function enhancement is needed.

This white paper first analyzes the network evolution architecture of 5G-Advanced and expounds on the technical development direction of 5G-Advanced from the three characteristics of Artificial Intelligence, Convergence, and Enablement. Artificial Intelligence represents network AI, including full use of machine learning, digital twins, recognition and intention network, which can enhance the capabilities of network's intelligent operation and maintenance. Convergence includes 5G and industry network convergence, home network convergence and space-air-ground network convergence, in order to realize the integration development. Enablement provides for the enhancement of 5G interactive communication and deterministic communication capabilities. It enhances existing technologies such as network slicing and positioning to better help the digital transformation of the industry.

The paper can be downloaded from China Mobile's website here or from Huawei's website here. A video of the paper launch is embedded below:

Nokia's Antti Toskala wrote a blog piece providing the first real glimpse of 5G-Advanced, here.

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Tuesday 27 July 2021

Introduction to 5G Reduced Capability (RedCap) Devices

Back in 2019, we wrote about Release-17 study item called NR-Lite (a.k.a. NR-Light). After the study started, it was renamed as RedCap or Reduced Capability.

We have now made a video tutorial on RedCap to not only explain what it is but also discuss some of the enhancements being discussed for 3GPP Release-18 (5G-Advanced). For anyone wanting to find out the differences between the baseline 5G devices with RedCap, without wanting to go too much in detail, can see the Tweet image for comparison.

The video and the slides of the tutorial are embedded below:

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Wednesday 7 July 2021

Different Types of RAN Architectures - Distributed, Centralized & Cloud


I come across a question relating to the different type of RAN architectures once per month on an average. Even though we have covered the topic as part of some or the other tutorial, we decided to do a dedicated tutorial on this.

The video and slides are embedded below

As always, feedback and comments welcome.

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Wednesday 30 June 2021

Open RAN Terminology and Players


When we made our little Open RAN explainer, couple of years back, we never imagined this day when so many people in the industry will be talking about Open RAN. I have lost track of the virtual events taking place and Open RAN whitepapers that have been made available just in the last month.

One of the whitepapers just released was from NTT Docomo, just in time for MWC 2021. You can see the link in the Tweet

Even after so much information being available, many people still have basic questions about Open RAN and O-RAN. I helped make an Open RAN explainer series and blogged about it here. Just last week, I blogged about the O-RAN explainer series that I am currently working on, here.

There were some other topics that I couldn't cover elsewhere so made some short videos on them for the 3G4G YouTube channel. The first video/presentation explains Open RAN terminology that different people, companies and organizations use. It starts with open interfaces and then looks at radio hardware disaggregation and compute disaggregation. Moving from 2G/3G/4G to 5G, it also explains the Open RAN approach to a decomposed architecture with RAN functional splits.

If you look at the Telecom Infra Project (TIP) OpenRAN group or O-RAN Alliance, the organizations driving the Open RAN vision and mission, you will notice many new small RAN players are joining one or both of them. In addition, you hear about other Open RAN consortiums that again include small innovative vendors that may not be very well known. 

The second video is an opinion piece looking at what is driving these companies to invest in Open RAN and what can they expect as return in future.

As always, all 3G4G videos' slides are available on our SlideShare channel.

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Saturday 19 June 2021

Edge Computing - Industry Vertical Viewpoints


A sub-set of 3GPP Market Representation Partners hosted a 2-part webinar series in April 2021 looking at edge computing for industry verticals and on-going standardisation work in 3GPP. The webinar was attended by a mix of organisations from both verticals and the telecommunication industry, helping to share a common understanding on edge computing. 

The first webinar brought together experts from the 5G Automotive Association (5GAA), the 5G Alliance for Connected Industry and Automation (5G-ACIA), Edge Gallery, ETSI Multi-access edge computing (MEC) and the Automotive Edge Computing Consortium (AECC) to highlight opportunities and updates on how diverse market sectors can benefit from offloading data at the edge of the network. Further insights came from interactive discussions and polling with participants. This webinar is part of a 5G user webinar and workshop series designed for industry verticals co-hosted by 5G-IA, 5GAA, 5G-ACIA and PSCE as Market Representation Partners of 3GPP.

This video embedded below is the recording of the webinar on Tuesday 20 April on edge computing - part one, giving an educational deep dive on industry vertical viewpoints. 5GAA (5G Automotive Association) gives an overview of its white paper, use cases and upcoming trials for Cellular-V2X in the automotive sector. Edge Gallery shows how it is supporting the Industrial Internet of Things with its 5G open-source solutions and application development support. ETSI MEC explain its common and extensible application enabling platform for new business opportunities. 5G-ACIA (5G Alliance for Connected Industry and Automation) describes new work on the applicability of 5G industrual edge computing within the associaton. The Automotive Edge Computing Consortium (AECC) brings insights into how it is driving data to the edge.

Bios and PDF presentations as follows:

Global5G has a summary with main takeaways and poll findings here. The following is from there:

Main takeaways

  1. The webinar was an excellent deep-dive into the edge computing landscape highlighting on-going work in automotive, manufacturing and the Industrial Internet of Things, as well as standardisation work in ETSI and open-source approaches. 
  2. It illustrated the value of edge computing with strong signs coming from industry in terms of growing interest and adoption roadmaps. There is an impressive number of initiatives across the globe embracing edge computing, with examples of cooperation globally as seen in 5GAA, 5G-ACIA, AECC and ETSI MEC. 
  3. Industrial automation, digital twins and infrastructure control among the main drivers for growing demand. 
  4. Collaboration on edge computing is essential and will become even more important as applications increasingly move to the edge. Continued discussions are needed to have greater clarity at multiple layers: business and technology, SW and HW. Collaboration can also support efforts to educate consumers and businesses, both key to uptake and achieving network compliant rollout.  
  5. The collaboration underpinning the 3GPP MRP webinar series is an excellent example of how we can intensify joint efforts across the ecosystem working towards convergence and ensuring RoI, e.g. for telecom investments. 

Poll Findings - Participant viewpoints

Where would you position your organisation in terms of implementing edge computing?

Only 16% of respondents already have a commercial strategy in place for edge computing while 26% are starting to develop one. Therefore 42% are expected to have one in short term. 30% are at early learning stage to understand market opportunities and 28% are exploring its potential. 

In which verticals do you expect the first implementations other than automotive?

The automotive sector is an early mover in edge computing, as testified by 5GAA and AECC presentations in the webinar with both having published studies and white papers. 5GAA is planning trials in 2021 in various locations globally so another webinar on this topic in 2022 would be helpful. After automotive, manufacturing is expected to be the next sector to implement edge, as testified by the 5G-ACIA presentation. All three associations are market representation partners of 3GPP, with 5GAA also contributing to standardisation work. In the 5G PPP, 5GCroCo (cross-border automotive use cases) has contributed to standardisation activities of both 5GAA and AECC. Gaming, AR/VR and media is the next sector expected to adopt edge computing. 

What are your top 2 priority requirements for edge computing? 

Low latency is the top requirement for most respondents (33%) followed by interoperability and service continuity (both on 20.5%) with transferring and processing large volumes of data and very high reliability in joint third place (both on 12.8%). It' will be important to see how many of these requirements feature in early deployments as not all of them will be there at first rollout. The poll also shows how requirements combine together, e.g. 2 priority requirements: Low latency + very high reliability; Interoperability + Service continuity; Interoperability + Low latency; 3 requirements: Interoperability + Service continuity + Transferring and processing large volumes of data and 4 requirements: Interoperability + Service continuity + Low latency + Transferring and processing large volumes of data. 

Part 2 of this webinar is available here.

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Thursday 10 June 2021

Nokia veterans Harri Holma and Antti Toskala explain 5G Basics

An online conference on 5G is currently going on. 'Backed by 5G: Technology for Impact', is hosted by Start North as a part of the Aalto University Summer Course 5G Hack the Mall.

It is a two-week online conference which gathers the industry experts, entrepreneurs and policymakers together to discuss, present and question how 5G will affect our society, economy and everyday life. We want you to join the change by offering a chance to learn from the best, to start or strengthen your journey to expertise in 5G. With the support of our partners, you have the possibility to listen and get your questions answered by the global 5G leaders from the leading companies, academia, NGOs and public institutions, which all are daily involved with changing the world and enabling change with the latest technology.

The current conference features couple of Nokia experts who are well known in the industry for their books on the mobile technologies. Dr. Harri Holma, Fellow, Nokia Bell Labs, spoke on "What is Good to Know About 5G Technology Components". His talk is embedded below:


The second talk is by Dr. Antti Toskala, Fellow, Nokia Bell Labs, on Radio Access (5G Physical Layer). His talk is embedded below

Slides are shared to the 5G Summer School participants. If you are keen to get your hands on the slides, please email: hello@startnorth.com. You can watch all the videos from the event on the Start North YouTube channel here.

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Monday 7 December 2020

Nokia Lectures in Collaboration with Bangalore University

Nokia recently delivered some lectures virtually to Bangalore University students. The talks covered a variety of talks from LTE to 5G, Security & IMS. The playlist from Nokia is embedded below. The video contains following topics:

Part 1: 5G - General Introduction and IoT Specific Features
Part 2: 5G Overview
Part 3: Network Security Practices and Principles
Part 4: LTE Network Architecture - Interface and Protocols
Part 5: IMS - IP Multimedia Subsystem

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Tuesday 10 November 2020

Network Slicing Tutorials and Other Resources

I have received quite a few requests to do a 5G Network Slicing tutorial but have still not got around to doing it. Luckily there are so many public resources available that I can get away with not doing one on this topic. 


This Award Solutions webinar by Paul Shepherd (embedded below) provides good insights into network slicing, what it is, how it efficiently enables different services in 5G networks, and the architectural changes in 5G required to support it.

Then there is also this myth about 3 slices in the network. The GSMA slice template is a good starting point for an operator looking to do network slicing in their 5G networks. The latest version is 3.0, available here.


As this picture (courtesy of Phil Kendall) shows, it's not a straightforward task.  

Alistair URIE from Nokia Bell Labs points out some common misconceptions people have with Network Slicing:

  1. Multiple slices may share the same cell and the same RU in each slice
  2. Single UE may have up to 8 active slices but must have a single CU-CP instance to terminate the common RRC 
  3. Slicing supports more than 3 slices 

Back in March, China Mobile, Huawei, Tencent, China Electric Power Research Institute, and Digital Domain have jointly released the Categories and Service Levels of Network Slice White Paper to introduce the industry’s first classification of network slice levels. The new white paper dives into the definitions, solutions, typical scenarios, and evolution that make up the five levels of network slices. It serves as an excellent reference to provide guidance in promoting and commercializing network slicing, and lays a theoretical foundation for the industry-wide application of network slicing.

The whitepaper describes the different phases as:

Phase 1 (ready): As mentioned above, the 5G transport network and 5G core network support different software-based and hardware-based isolation solutions. On the 5G NR side, 5QIs (QoS scheduling mechanism) are mainly used to achieve software-based isolation in WAN scenarios. Alternatively, campus-specific 5G NR (including micro base stations and indoor distributed base stations) is used to implement hardware-based isolation in LAN scenarios. In terms of service experience assurance, 5QIs are used to implement differentiated SLA assurance between slices. In terms of slice OAM capabilities, E2E KPIs can be managed in a visualized manner. This means that from 2020 on, Huawei is ready to deliver commercial use of E2E slicing for common customers and VIP customers of the public network and common customer of general industries (such as UHD live broadcast and AR advertisement).

Phase 2 (to be ready in 2021): In terms of isolation, the 5G NR side supports the wireless RB resource reservation technology (including the static reservation and dynamic reservation modes) to implement E2E network resource isolation and slicing in WAN scenarios. In terms of service experience assurance, features such as 5G LAN and 5G TSN are enhanced to implement differentiated and deterministic SLA assurance between different slices. In terms of slice OAM, on the basis of tenant-level KPI visualization, the limited self-service of the industry for rented slices can be further supported. In this phase, operators can serve VIP customers in common industries (such as AR/VR cloud games and drone inspection), dedicated industry customers (such as electric power management information region, medical hospital campus, and industrial campus), and dedicated industry customers (such as electric power production control region and public security).

Phase 3 (to be ready after 2022): In this phase, 5G network slicing supports real dynamic closed-loop SLAs based on AI and negative feedback mechanism, implementing network self-optimization and better serving industries (such as 5G V2X) with high requirements on mobility, roaming, and service continuity. In addition, industry-oriented comprehensive service capabilities will be further enhanced and evolved.

A more technical presentation from Nokia is available here. The video below shows how innovations in IP routing and SDN work together to implement network slicing in the transport domain.

If you know some other good resources and tutorials worth sharing, add them in the comments below.

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Monday 22 June 2020

Carrier Aggregation (CA) and Dual Connectivity (DC)


This topic keeps coming up every few months with either someone asking me for clarifications or someone asking us to make a video. While I don't think I will mange to get round to making a video sometime soon, there are some excellent resources available that should help a new starter. Here they are in an order I think works best



The first resource that I think also works best is this webinar / training from Award Solutions. It covers this topic well and the image at the top of the post is a god summary for someone who already understands the technology.


It may also help to understand that in the 5G NSA can have 4G carrier aggregation as well as 5G carrier aggregation in addition to dual connectivity.


If you saw the video earlier, you noticed that DC actually came as part of LTE in Release-12. We covered it in our Telecom Infrastructure blog here. NTT Docomo Technical journal had a detailed article on 'Carrier Aggregation Enhancement and Dual Connectivity Promising Higher Throughput and Capacity' that covered DC in a lot more technical detail, albeit from LTE point of view only. The article is available here. A WWRF whitepaper from the same era can also provide more details on LTE Small Cell Enhancement by Dual Connectivity. An archived copy of the paper is available here.

Another fantastic resource is this presentation by Rapeepat Ratasuk and Amitava Ghosh from Mobile Radio Research Lab, Nokia Bell Labs. The presentation is available here and details the MCG (Master Cell Group) Split Bearer and SCG (Secondary Cell Group) Split Bearer, etc. This article from Ericsson also provides more detail on this topic while ShareTechNote takes it one level even deeper with technical details and signalling here and here.

So hopefully this is a good detailed starting point on this topic, until we manage to make a simple video someday.

Tuesday 19 May 2020

5G Dynamic Spectrum Sharing (DSS)

5G Dynamic Spectrum Sharing is a hot topic. I have already been asked about multiple people for links on good resources / whitepapers. So here is what we liked, feel free to add anything else you found useful as part of comments.


Nokia has a nice high level overview of this topic which is available here. I really liked the decision tree as shown in the tweet above. I am going to quote a section here that is a great summary to decide if you want to dive deeper.

DSS in the physical layer
DSS allows CSPs to share resources dynamically between 4G and 5G in time and/or frequency domains, as shown on the left of Figure 3. It’s a simple idea in principle, but we also need to consider the detailed structure at the level of the resource block in order to understand the resource allocations for the control channels and reference signals. A single resource block is shown on the right side of Figure 3.

The 5G physical layer is designed to be so similar to 4G in 3GPP that DSS becomes feasible with the same subcarrier spacing and similar time domain structure. DSS is designed to be backwards compatible with all existing LTE devices. CSPs therefore need to maintain LTE cell reference signal (CRS) transmission. 5G transmission is designed around LTE CRS in an approach called CRS rate matching.

5G uses demodulation reference signals (DMRS), which are only transmitted together with 5G data and so minimize any impact on LTE capacity. If all LTE devices support Transmission Mode 9 (TM9), then the shared carrier has lower overheads because less CRS transmission is required. The control channel transmission and the data transmission can be selected dynamically between LTE and 5G, depending on the instantaneous capacity requirements.


The second resource is this Rohde & Schwarz webinar here. As can be seen in the tweet above, it provides nice detailed explanation.

Finally, we have a Comprehensive Deployment Guide to Dynamic Spectrum Sharing for 5G NR and 4G LTE Coexistence, which is a nice and detailed whitepaper from Mediatek. Quoting a small section from the WP for anyone not wanting to go too much in deep:

The DSS concept is based on the flexible design of NR physical layer. It uses the idea that NR signals are transmitted over unused LTE resources. With LTE, all the channels are statically assigned in the time-frequency domain, whereas the NR physical layer is extremely flexible for reference signals, data and control channels, thus allowing dynamic configurations that will minimize a chance of collision between the two technologies. 

One of the main concepts of DSS is that only 5G users are made aware of it, while the functionalities of the existing LTE devices remain unaffected (i.e. LTE protocols in connected or idle mode). Therefore, fitting the flexible physical layer design of NR around that of LTE is needed in order to deploy DSS on a shared spectrum. This paper discusses the various options of DSS implementation, including deployment challenges, possible impacts to data rates, and areas of possible improvements.

NR offers a scalable and flexible physical layer design depicted by various numerologies. There are different subcarrier spacing (SCS) for data channels and synchronization channels based on the band assigned. This flexibility brings even more complexity because it overlays the NR signals over LTE, which requires very tight coordination between gNB and eNB in order to provide reliable synchronization in radio scheduling.

The main foundation of DSS is to schedule NR users in the LTE subframes while ensuring no respective impact on LTE users in terms of essential channels, such as reference signals used for synchronization and downlink measurements. LTE Cell Reference Signals (CRS) is typically the main concept where DSS options are designated, as CRS have a fixed time-frequency resource assignment. The CRS resources layout can vary depending on the number of antenna ports. More CRS antenna ports leads to increased usage of Resource Elements (REs). CRS generates from 4.76% (1 antenna port) up to 14.29% (4 antenna ports) overhead in LTE resources. As CRS is the channel used for downlink measurements, avoiding possible collision with CRS is one of the foundations of the DSS options shown in figure 1. The other aspect of DSS design is to fit the 5G NR reference signals within the subframes in a way to avoid affecting NR downlink measurements and synchronization. For that, DSS considers the options shown in figure 1 to ensure NR reference signals such as Synchronization Signal Block (SSB) or Demodulation Reference Signal (DMRS) are placed in time-frequencies away from any collision with LTE signals.

MBSFN, option 1 in figure 1, stands for Multi-Broadcast Single-Frequency Network and is used in LTE for point-to-multipoint transmission such as eMBMS (Evolved Multimedia Broadcast Multicast Services). The general idea of MBSFN is that specific subframes within an LTE frame reserve the last 12 OFDM symbols of such subframe to be free from other LTE channel transmission. These symbols were originally intended to be used for broadcast services and are “muted” for data transmission in other LTE UE. Now this idea has been adjusted for use in a DSS concept, so that these reserved symbols are used for NR signals instead of eMBMS. While in general LTE PDCCH can occupy from 1 to 3 symbols (based on cell load), the first two OFDM symbols of such MBSFN subframe are used for LTE PDCCH, and DSS NR UE can use the third symbol. Using MBSFN is completely transparent to legacy LTE-only devices from 3GPP Release 9 onwards, as such LTE UE knows that these subframes are used for other purposes. In this sense this is the simplest way of deploying DSS. This method has disadvantages though. The main one is that if MBSFN subframes are used very frequently and it takes away resources from LTE users, heavily reducing LTE-only user throughput. Note that option 1 shown in figure 1 does not require LTE MBSFN Reference Signals to be used, because the MBSFN subframe is used to mute the subframe for DSS operation only, and LTE CRS shall only be transmitted in the non-MBSFN region (within the first two symbols) of the MBSFN subframe.

The two other options illustrated in figure 1 are dealing with non-MBSFN subframes that contain LTE reference signals. Option 2 is ‘mini-slot’ based; mini-slot scheduling is available in NR for URLLC applications that require extremely low latency. The symbols can be placed anywhere inside the NR slot. In respect to DSS, mini-slot operation just eliminates the usage of the symbols that contain LTE CRS and schedule only free ones for NR transmission. The basic limitation of this method comes from the concept itself. It is not very suitable for eMBB applications as too many resources are outside of NR scheduling. However it still can be utilized in some special cases like 30 kHz SSB insertion which will be described later in this paper.

Option 3 is based on CRS rate matching in non-MBSFN subframes, and it is expected to be the one most commonly used for NR data channels. In this option, the UE performs puncturing of REs used by LTE CRS so that the NR scheduler knows which REs are not available for NR data scheduling on PDSCH (Physical Downlink Shared Channel). The implementation of this option can be either Resource Block (RB)-level when the whole RB containing LTE CRS is taken out of NR scheduling, or RE-level where NR PDSCH scheduling avoids particular REs only. The end result of this method is that the scheduler will reduce the NR PDSCH transport block size as the number of REs available for scheduling become less in a slot.


Personally, I am not a big fan of DSS mainly because I think it is only useful in a very few scenarios. Also, it helps operators show a 5G logo but doesn't provide a 5G experience by itself. Nevertheless, it can come in handy for the coverage layer of 5G.


In one of the LinkedIn discussions (that I try and avoid mostly) somebody shared this above picture of Keysight Nemo DSS lab test results. As you can see there is quite a bit of overhead with DSS.