An Early View of 3GPP Release-18 5G-Advanced Topics

5G is hot at the moment. While the operators are busy rolling out the networks based on Release-15/16 features, 3GPP is working on finalising Release-17 specifications and laying the foundations for Rel-18.

The latest issue of 3GPP Highlights magazine (I prefer the PDF) contains a lot of valuable technical content, in addition to many other articles. The technical content includes:

• An early view of the RAN Topics for 5G-Advanced
• 5G Advanced in the Making – The TSG SA approach to Release 18
• Application Enablement Standards in 3GPP – Maximizing the potential of 5G!
• RAN3 flourishing in this time of change
• Enhanced support of Industrial IoT in the 5G System (Rel-17)
• Autonomous Network standardization in WG SA5
• Rel-17 Edge Computing and Network Slicing charging (WG SA 5)
• Media Production over 5G NPN

While I am not going into too much detail here, I want to highlight the 5G-Advanced topics that will be under discussion over the next couple of months. The final list will be approved by 3GPP TSGs SA, RAN and CT in December 2021.

Dr. Wanshi Chen, 3GPP TSG RAN Chair provided an early view of the RAN topics for 5G-Advanced. 

Topics Under Discussion

As well as taking a tentative decision on an 18-month duration for Release 18, the RAN workshop endorsed a list of topics for subsequent email discussions. Some of the topics in the following list also have a set of example areas, serving as a starting point for further refinement:

• Evolution for downlink MIMO, with the following example areas:
• Further enhancements for CSI (e.g., mobility, overhead, etc.)
• Evolved handling of multi-TRP (Transmission Reception Points) and multi-beam
• CPE (customer premises equipment) -specific considerations
• Uplink enhancements, with the following example areas:
• >4 Tx operation
• Enhanced multi-panel/multi-TRP uplink operation
• Frequency-selective precoding
• Further coverage enhancements
• Mobility enhancements, with the following example areas:
• Layer 1/layer 2 based inter cell mobility
• DAPS (Dual Active Protocol Stack)/CHO (Conditional HandOver) related improvements
• FR2 (frequency range 2)-specific enhancements
• Additional topological improvements (IAB and smart repeaters), with the following example areas:
• Mobile IAB (Integrated Access Backhaul)/Vehicle mounted relay (VMR)
• Smart repeater with side control information
• Enhancements for XR (eXtended Reality), with the following example areas:
• KPIs/QoS, application awareness operation, and aspects related to power consumption, coverage, capacity, and mobility
• Note: only power consumption/coverage/mobility aspects specific to XR
• Sidelink enhancements (excluding positioning), with the following example areas:
• SL enhancements (e.g., unlicensed, power saving enhancements, efficiency enhancements, etc.)
• SL relay enhancements
• Co-existence of LTE V2X & NR V2X
• RedCap evolution (excluding positioning), with the following example areas:
• New use cases and new UE bandwidths (5MHz?)
• Power saving enhancements
• NTN (Non-Terrestrial Networks) evolution
• Including both NR & IoT (Internet of Things) aspects
• Evolution for broadcast and multicast services
• Including both LTE based 5G broadcast and NR MBS (Multicast Broadcast Services)
• Expanded and improved Positioning, with the following example areas:
• Sidelink positioning/ranging
• Improved accuracy, integrity, and power efficiency
• RedCap positioning
• Evolution of duplex operation, with the following example areas:
• Deployment scenarios, including duplex mode (TDD only?)
• Interference management
• AI (Artificial Intelligence)/ML (Machine Learning), with the following example areas:
• Air interface (e.g., Use cases to focus, KPIs and Evaluation methodology, network and UE involvement, etc.)
• NG-RAN
• Network energy savings, with the following example areas:
• KPIs and evaluation methodology, focus areas and potential solutions
• Additional RAN1/2/3 candidate topics, Set 1:
• UE power savings
• Enhancing and extending the support beyond 52.6GHz
• CA (Carrier Aggregation)/DC (Dual-Connectivity) enhancements (e.g., MR-MC (Multi-Radio/Multi-Connectivity), etc.)
• Flexible spectrum integration
• RIS (Reconfigurable Intelligent Surfaces)
• Others (RAN1-led)
• Additional RAN1/2/3 candidate topics, Set 2:
• UAV (Unmanned Aerial Vehicle)
• IIoT (Industrial Internet of Things)/URLLC (Ultra-Reliable Low-Latency Communication)
• <5MHz in dedicated spectrum
• Other IoT enhancements/types
• HAPS (High Altitude Platform System)
• Network coding
• Additional RAN1/2/3 candidate topics, Set 3:
• Inter-gNB coordination, with the following example areas:
• Inter-gNB/gNB-DU multi-carrier operation
• Inter-gNB/gNB-DU multi-TRP operation
• Enhancement for resiliency of gNB-CU
• Network slicing enhancements
• MUSIM (Multiple Universal Subscriber Identity Modules)
• UE aggregation
• Security enhancements
• SON (Self-Organizing Networks)/MDT (Minimization of Drive Test)
• Others (RAN2/3-led)
• Potential RAN4 enhancements

Dr. Georg Mayer, 3GPP TSG SA Chair provides the TSG SA approach to 3GPP Release-18

The candidate items for Rel-18 include:

• Immersive Media and Virtual/Artificial/Extended Reality (XR) Media support in Working Group (WG) SA4 and WG SA2.
• New work areas for Internet of Things (e.g. passive IoT (WG SA2) and application capability exposure for IoT platforms (WG SA6)).
• Proposals to for Artificial Intelligence and Machine Learning Services Transport and Management (WGs SA2, SA5).
• Concepts for integration and migration of existing vertical infrastructure, e.g. for railway networks (WG SA6).
• Examples for proposed enhancements to existing 3GPP services and functionalities include:
• Network Slicing (WGs SA2, SA5)
• Edge Computing (WGs SA2, SA5, SA6)
• Autonomous Networks (WG SA5)
• Service Based Architecture (WGs SA2, SA5)
• Northbound APIs (WG SA6)
• Non-Public Networks (WG SA2)
• Satellite 5G Networks (WG SA2)
• Drone support (WG SA2)
• 5G Multicast and Broadcast (WG SA2)
• Location Services (WG SA2, SA6)
• Management Data Analytics (WG SA5)
• Mission Critical Services (WG SA6)

None of these features are final but we will know in the next few months what will be included as part of Rel-18 and what won't. In the meantime, do check out the latest issue of 3GPP Highlights here.

Related Posts: 

• The 3G4G Blog: 3GPP's 5G-Advanced Workshop Summary
• The 3G4G Blog: 3GPP's 5G-Advanced Technology Evolution from a Network Perspective Whitepaper
• The 3G4G Blog: '5G RAN Release 18 for Industry Verticals' Webinar Highlights
• The 3G4G Blog: 3GPP RAN Plenary Update and Evolution towards 5G-Advanced
• The 3G4G Blog: Initiative to Remove Non-inclusive terms from 3GPP Specifications
• The 3G4G Blog: 3GPP Release 16 Description and Summary of Work Items
• The 3G4G Blog: 3GPP Standards on Edge Computing 

3GPP's 5G-Advanced Workshop Summary

From 28 June to 02 July 2 2021, 3GPP held its first internal workshop on the radio specific content of Release 18, reviewing over 500 company and partner organization’s presentations, to identify topics for the immediate and longer-term commercial needs for:

• eMBB (evolved Mobile BroadBand);
• Non-eMBB evolution;
• Cross-functionalities for both eMBB and non-eMBB driven evolution.

All the documents related to the workshop can be found on the 3GPP website here. The workshop details is available in RWS-210002 while the summary of the RAN Rel-18 workshop is available in RWS-210659.

The following is from 3GPP's news article on 5G-Advanced workshop:

Wanshi Chen, the TSG RAN Chair, summarized that the example areas under each topic serve as a starting point, each subject to further update or removal during the email discussion period - with additional topics still possible, up to the September e-meeting. That RAN#93-e meeting (13-17 September 2021) will see progress on ‘high-level descriptions’ of the objectives for each topic.

List of Topics:

1. Evolution for downlink MIMO, with the following example areas:

• Further enhancements for CSI (e.g., mobility, overhead, etc.)
• Evolved handling of multi-TRP (Transmission Reception Points) and multi-beam
• CPE(customer premises equipment)-specific considerations

2. Uplink enhancements, with the following example areas:

• >4 Tx operation
• Enhanced multi-panel/multi-TRP uplink operation
• Frequency-selective precoding
• Further coverage enhancements

3. Mobility enhancements, with the following example areas:

• Layer 1/layer 2 based inter cell mobility
• DAPS (Dual Active Protocol Stack)/CHO (Conditional HandOver) related improvements
• FR2 (frequency range 2)-specific enhancements

4. Additional topological improvements (IAB and smart repeaters), with the following example areas:

• Mobile IAB (Integrated Access Backhaul)/Vehicle mounted relay (VMR)
• Smart repeater with side control information

5. Enhancements for XR (eXtended Reality), with the following example areas:

• KPIs/QoS, application awareness operation, and aspects related to power consumption, coverage, capacity, and mobility (Note: only power consumption/coverage/mobility aspects specific to XR)

6. Sidelink enhancements (excluding positioning), with the following example areas:

• SL enhancements (e.g., unlicensed, power saving enhancements, efficiency enhancements, etc.)
• SL relay enhancements
• Co-existence of LTE V2X & NR V2X

7. RedCap evolution (excluding positioning), with the following example areas:

• New use cases and new UE bandwidths (5MHz?)
• Power saving enhancements

8. NTN (Non-Terrestrial Networks) evolution

• Including both NR & IoT (Internet of Things) aspects

9. Evolution for broadcast and multicast services

• Including both LTE based 5G broadcast and NR MBS (Multicast Broadcast Services)

10. Expanded and improved Positioning, with the following example areas:

• Sidelink positioning/ranging
• Improved accuracy, integrity, and power efficiency
• RedCap positioning

11. Evolution of duplex operation, with the following example areas:

• Deployment scenarios, including duplex mode (TDD only?)
• Interference management

12. AI (Artificial Intelligence)/ML (Machine Learning), with the following example areas:

• Air interface (e.g., Use cases to focus, KPIs and Evaluation methodology, network and UE involvement, etc.)
• NG-RAN

13. Network energy savings, with the following example areas:

• KPIs and evaluation methodology, focus areas and potential solutions

14. Additional RAN1/2/3 candidate topics, Set 1:

• UE power savings
• Enhancing and extending the support beyond 52.6GHz
• CA (Carrier Aggregation)/DC (Dual-Connectivity) enhancements (e.g., MR-MC (Multi-Radio/Multi-Connectivity), etc.)
• Flexible spectrum integration
• RIS (Reconfigurable Intelligent Surfaces)
• Others (RAN1-led)

15. Additional RAN1/2/3 candidate topics, Set 2:

• UAV (Unmanned Aerial Vehicle)
• IIoT (Industrial Internet of Things)/URLLC (Ultra-Reliable Low-Latency Communication)
• <5MHz in dedicated spectrum
• Other IoT enhancements/types
• HAPS (High Altitude Platform System)
• Network coding

16. Additional RAN1/2/3 candidate topics, Set 3:

• Inter-gNB coordination, with the following example areas:
• Inter-gNB/gNB-DU multi-carrier operation
• Inter-gNB/gNB-DU multi-TRP operation
• Enhancement for resiliency of gNB-CU
• Network slicing enhancements
• MUSIM (Multiple Universal Subscriber Identity Modules)
• UE aggregation
• Security enhancements
• SON (Self-Organizing Networks)/MDT (Minimization of Drive Test)
• Others (RAN2/3-led)

17. Potential RAN4 enhancements 

The latest timeline for Release-17/18 is as shown in the diagram above. 

The official 3GPP Release-18 page is here. This link is better to navigate through features in different 3GPP releases.

Related Posts: 

• The 3G4G Blog: '5G RAN Release 18 for Industry Verticals' Webinar Highlights
• The 3G4G Blog: 3GPP's 5G-Advanced Technology Evolution from a Network Perspective Whitepaper
• The 3G4G Blog: 3GPP RAN Plenary Update and Evolution towards 5G-Advanced
• The 3G4G Blog: Initiative to Remove Non-inclusive terms from 3GPP Specifications
• The 3G4G Blog: Introduction to 5G Reduced Capability (RedCap) Devices
• The 3G4G Blog: 3GPP Standards on Edge Computing
• The 3G4G Blog: ATIS Webinar on '5G Standards Developments in 3GPP Release 16 and Beyond' 

5G for Content Acquisition and Distribution

The Cambridge Wireless (CW) Content Production & Delivery group recently delivered a two part webinar series exploring ‘5G for content acquisition and distribution’ These online events introduced participants to the state of play with 5G for content distribution and production and the path to delivering the benefits 5G.

Aspirational discussion of benefits of 5G for content production and distribution needs to be turned into operational reality. 5G will enhance what is possible to be achieved with current mobile systems and the advantages to distribution and consumption are obvious through bigger pipes and enhanced agility to support ever evolving content and application platforms. The possibilities for content production and acquisition are also exiting but may be less obvious. 5G will allow service and capacity to be delivered where required through use of small cell and potentially highly localised private 5G networks, edge computing and support of a wide range of equipment and applications (not just those use cases directly involved in content acquisition).

The first session on 24 Nov 2020 in the series considers the role of 5G for content distribution and security. It covers the role of 5G for the creation of a more varied and vibrant ecosystem for content and the desire of some content creators for greater focus on security.

Henry Johnson, Director, Plum Consulting, '5G opportunities in the provision of content distribution' - 5G services promise to provide connectivity performance in terms of bandwidth and latency which have hitherto been possible only with fixed network connectivity. This session will look into the capabilities and potential limitations of 5G services once deployed and what that might mean for content delivery to consumers. [PPT presentation]

Malcolm Brew, University of Strathclyde, ‘5G-enabled remote broadcast’ - Malcolm will share some Strathclyde’s insights over the last 10 years in working with BBC and Ofcom on ‘Spectrum Sharing’ and how this has recently been lead to working in an IBC Accelerator Program ‘5G In Remote Production’ [PDF] 

For limited time, the recording is available here.

The 3G4G Blog: LTE / 5G Broadcast Evolution - https://t.co/nMM6VvxGbg via @5Gxcast #3G4G5G #IEEE5G #5GIEEE #eMBMS #LTEBroadcast #MissionCriticalComms pic.twitter.com/aSxdsFkX9A

— 3G4G (@3g4gUK) August 29, 2019

The following is the description from session 2, on 2nd Dec 2020:

Join the CW Content Production and Delivery Group’s aspirational discussion of benefits of 5G for content production and distribution needs to be turned into operational reality.

There is no doubt 5G will enhance what is possible to be achieved with current mobile systems and the advantages to distribution and consumption are obvious through bigger pipes and enhanced agility to support ever evolving content and application platforms.

The possibilities for content production and acquisition are also exciting, but may be less obvious. 5G will allow service and capacity to be delivered where required through use of small cell and potentially highly localised private 5G networks, edge computing and support of a wide range of equipment and applications (not just those use cases directly involved in content acquisition).

Ian Wagdin, Senior Technology Transfer Manager, BBC R&D, '5G in Content Production, work in standards and deployments' - A look at what’s here and what’s coming and how 5G may impact broadcast workflows. [PDF]

Paola Sunna, Technology and Innovation Department, EBU, '5G for Content Production' - EBU perspective on 5G for professional content production and challenges/ambitions in the Horizon 2020 project 5G-RECORDS. [PDF] 

For limited time, the recording is available here.

A nice talk looking at 5G and Broadcast - 'BBC, 5G and me' by Ed King, Principal Architect, BBC at @TheIET #5GUnleashed 2020 conference - https://t.co/RtTIxZnvN4#Free5GTraining #eMBMS #5Gbroadcast pic.twitter.com/j0d6r7Xqeq

— 5G Training (@5Gtraining) March 6, 2020

Other Recent News / Articles / Videos on 4G/5G Broadcast:

• SoftBank Corp. Showcases 5G-powered Entertainment and Advanced Technologies at Pop Culture Complex (link)
• 5G TODAY: BAVARIA’S BROADCAST TRIALS (link)
• Webinar: The role of broadcast and multicast in 5G-TOURS: High-quality video services distribution (link)
• Delivering Media with 5G Technology: FeMBMS, 5G-Xcast and beyond (link)
• 5G TODAY: 5G Broadcast trial using FeMBMS (link)
• 5G Today: On the Road to 5G Broadcast (link)

Related Posts:

• The 3G4G Blog: LTE / 5G Broadcast Evolution
• The 3G4G Blog: 5G Dynamic Spectrum Sharing (DSS)
• The 3G4G Blog: Multicast Operation on Demand (MooD) and Service Continuity for eMBMS 

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.  

That is 37 attributes each of which can take multiple values. The permutations are massive.

— Dr. Dan Warren (@TMGB) October 18, 2019

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.

Related Posts:

• The 3G4G Blog: 5G Slicing Templates
• The 3G4G Blog: End-to-end Network Slicing in 5G
• The 3G4G Blog: AI your Slice to 5G Perfection 

Positioning Techniques for 5G NR in 3GPP Release-16

I realised that I have not looked at Positioning techniques a lot in our blogs so this one should be a good summary of the latest positioning techniques in 5G.

Qualcomm has a nice short summary here: Release 16 supports multi-/single-cell and device-based positioning, defining a new positioning reference signal (PRS) used by various 5G positioning techniques such as roundtrip time (RTT), angle of arrival/departure (AoA/AoD), and time difference of arrival (TDOA). Roundtrip time (RTT) based positioning removes the requirement of tight network timing synchronization across nodes (as needed in legacy techniques such as TDOA) and offers additional flexibility in network deployment and maintenance. These techniques are designed to meet initial 5G requirements of 3 and 10 meters for indoor and outdoor use cases, respectively. In Release 17, precise indoor positioning functionality will bring sub-meter accuracy for industrial IoT use cases.

I wrote about the 5G Americas white paper titled, "The 5G Evolution: 3GPP Releases 16-17" highlighting new features in 5G that will define the next phase of 5G network deployments across the globe. The following is from that whitepaper:

Release-15 NR provides support for RAT-independent positioning techniques and Observed Time Difference Of Arrival (OTDOA) on LTE carriers. Release 16 extends NR to provide native positioning support by introducing RAT-dependent positioning schemes. These support regulatory and commercial use cases with more stringent requirements on latency and accuracy of positioning.25 NR enhanced capabilities provide valuable, enhanced location capabilities. Location accuracy and latency of positioning schemes improve by using wide signal bandwidth in FR1 and FR2. Furthermore, new schemes based on angular/spatial domain are developed to mitigate synchronization errors by exploiting massive antenna systems.

The positioning requirements for regulatory (e.g. E911) and commercial applications are described in 3GPP TR 38.855. For regulatory use cases, the following are the minimum performance requirements:

• Horizontal positioning accuracy better than 50 meters for 80% of the UEs.
• Vertical positioning accuracy better than 5 meters for 80% of the UEs.
• End-to-end latency less than 30 seconds.

For commercial use cases, for which the positioning requirements are more stringent, the following are the starting-point performance targets

• Horizontal positioning accuracy better than 3 meters (indoors) and 10 meters (outdoors) for 80% of the UEs.
• Vertical positioning accuracy better than 3 meters (indoors and outdoors) for 80% of the UEs.
• End-to-end latency less than 1 second.

Figure 3.11 above shows the RAT-dependent NR positioning schemes being considered for standardization in Release 16:

• Downlink time difference of arrival (DL-TDOA): A new reference signal known as the positioning reference signal (PRS) is introduced in Release 16 for the UE to perform downlink reference signal time difference (DL RSTD) measurements for each base station’s PRSs. These measurements are reported to the location server.
• Uplink time difference of arrival (UL-TDOA): The Release-16 sounding reference signal (SRS) is enhanced to allow each base station to measure the uplink relative time of arrival (UL-RTOA) and report the measurements to the location server.
• Downlink angle-of-departure (DL-AoD): The UE measures the downlink reference signal receive power (DL RSRP) per beam/gNB. Measurement reports are used to determine the AoD based on UE beam location for each gNB. The location server then uses the AoDs to estimate the UE position.
• Uplink angle-of-arrival (UL-AOA): The gNB measures the angle-of-arrival based on the beam the UE is located in. Measurement reports are sent to the location server.
• Multi-cell round trip time (RTT): The gNB and UE perform Rx-Tx time difference measurement for the signal of each cell. The measurement reports from the UE and gNBs are sent to the location server to determine the round trip time of each cell and derive the UE position.
• Enhanced cell ID (E-CID). This is based on RRM measurements (e.g. DL RSRP) of each gNB at the UE. The measurement reports are sent to the location server.

UE-based measurement reports for positioning:

• Downlink reference signal reference power (DL RSRP) per beam/gNB
• Downlink reference signal time difference (DL RSTD)
• UE RX-TX time difference

gNB-based measurement reports for positioning:

• Uplink angle-of-arrival (UL-AoA)
• Uplink reference-signal receive power (UL-RSRP)
• UL relative time of arrival (UL-RTOA)
• gNB RX-TX time difference

NR adopts a solution similar to that of LTE LPPa for Broadcast Assistance Data Delivery, which provides support for A-GNSS, RTK and OTDOA positioning methods. PPP-PTK positioning will extend LPP A-GNSS assistance data message based on compact “SSR messages” from QZSS interface specifications. UE-based RAT-dependent DL-only positioning techniques are supported, where the positioning estimation will be done at the UE-based on assistance data provided by the location server.

Rohde&Schwarz have a 5G overview presentation here. This picture from that presentation is a good summary of the 3GPP Release-16 5G NR positioning techniques. This nice short video on "Release 16 Location Based Services Requirements" complements it very well. 

Related Posts:

• Connectivity Technology Blog: 5G Indoor Precise Positioning
• The 3G4G Blog: R&S Webinar on LTE-A Pro and evolution to 5G

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.

Nice new whitepaper - Nokia dynamic spectrum sharing for rapid 5G coverage rollout - https://t.co/HdnTz4ZIgr

via @nokianetworks #Free5Gtraining #5G #5GNR #5GNetworks #Nokia #4G #5GSpectrum #Spectrum #DSS #DynamicSpectrum pic.twitter.com/APSnW9vrUp

— 5G Training (@5Gtraining) May 7, 2020

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.

A nice webinar looking at 5G Dynamic Spectrum Sharing a.k.a. DSS. A simple explanation is, use MBSFN subframes to tell LTE users that these resource blocks are not available and then use that spectrum for 5G NR.https://t.co/ettybXHMWV pic.twitter.com/zq7BQ9ImdB

— 3G4G (@3g4gUK) December 7, 2019

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.

VodafoneZiggo launching 5G in Netherlands using DSS from Ericsson in 1800MHz band. Due to spectrum situation in Ned this is all VZ has at launch so it's 5G on the icon but offering customers only 10% faster speeds than they can get with 4G. https://t.co/BLirTX8XjU

— Keith Dyer (@keithdyer) April 28, 2020

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.

Multicast Operation on Demand (MooD) and Service Continuity for eMBMS

Many regular readers of this blog are aware that back in 2014 I wrote a post looking critically at LTE-Broadcast business case and suggested a few approaches to make it a success. Back in those days, 2014 was being billed as the year of LTE-Broadcast or eMBMS (see here and here for example). I was just cautioning people against jumping on the LTE-B bandwagon.

According to a recent GSA report 'LTE Broadcast (eMBMS) Market Update – March 2018':

• thirty-nine operators are known to have been investing in eMBMS demonstrations, trials, deployments or launches
• five operators have now deployed eMBMS or launched some sort of commercial service using eMBMS

Its good to see some operators now getting ready to deploy eMBMS for broadcast TV scenarios. eMBMS will also be used in Mission Critical Communications for the features described here.

In a recent news from the Australian operator Telstra:

Telstra is now streaming live sports content to a massive base of around 1.2 million devices each weekend and sports fans consume 37 million minutes of live content over our apps on any given weekend.

This increase brings new challenges to the way traffic on our mobile network is managed. Even though a large group of people might be streaming the same real-time content at the same time, we still need to ensure a high quality streaming experience for our customers.

This challenge makes our sporting apps a prime use case for LTE-Broadcast (LTE-B).

Earlier this year, we announced we would be turning on LTE-B functionality on the AFL Live Official app for Telstra customers with Samsung Galaxy S8 and Galaxy S9 devices. Following extensive testing, Telstra is the only operator in Australia – and one of the first in the world – to deploy LTE-B into its mobile network.

At a live demonstration in Sydney, over 100 Samsung Galaxy S8 and Galaxy S9 devices were on display showing simultaneous high definition content from the AFL Live Official app using LTE-B.

Its interesting to note here that the broadcast functionality (and probably intelligence) is built into the app.

According to another Telstra news item (emphasis mine):

The use of LTE-Broadcast technology changes the underlying efficiency of live video delivery as each cell can now support an unlimited number of users watching the same content with improved overall quality. To date though, LTE-B technology has required that a dedicated part of each cell’s capacity be set aside for broadcasting. This had made the LTE-B business case harder to prove in for lower streaming demand rates.

This has now changed as Telstra and our partners have enabled the world’s first implementation of the Multicast Operation on Demand (MooD) feature whereby cells in the network only need to configure for LTE-B when there are multiple users watching the same content.

This combined with the Service Continuity feature allows mobile users to move around the network seamlessly between cells configured for LTE-B and those which are not.

Earlier this year we announced our intention to enable LTE-Broadcast (LTE-B) across our entire mobile network in 2018. With MooD and service continuity we are one step closer to that goal as we head into another year of major growth in sporting content demand.

Supported by technology partners Ericsson and Qualcomm, Telstra has now delivered world first capability to ensure LTE-B can be delivered as efficiently as possible.

Service Continuity will allow devices to transition in and out of LTE-B coverage areas without interruption. For instance, you might be at a music festival streaming an event on your phone but need to leave the venue and make your way back home (where LTE-B is not in use). Service Continuity means you can continue to watch the stream and the transition will be seamless – even though you have the left the broadcast area.

Taking that a step further, MooD allows the network to determine how many LTE-B compatible devices in any given area are consuming the same content. MooD then intelligently activates or deactivates LTE-B, ensuring the mobile network is as efficient as possible in that location.

For example, if a die-hard football fan is streaming a match we will likely service that one user with unicast, as that is the most efficient way of delivering the content. However if more users in the same cell decide to watch the match, MooD makes the decision automatically as to whether it is more efficient to service those users by switching the stream to broadcasting instead of individual unicast streams.

Its good to see Ericsson & Qualcomm finally taking eMBMS to commercial deployment. Back in 2015, I added their videos from MWC that year. See post here.

I think the Telstra post already provides info on why MooD is needed but this picture from Qualcomm whitepaper above makes it much clearer. Back in 3G MBMS and early days or eMBMS, there used to be a feature called counting, MooD is effectively doing the same thing.

For Service Continuity, this paper 'Service Continuity for eMBMS in LTE/LTE-Advanced Network: Standard Analysis and Supplement' by Ngoc-Duy Nguyen and Christian Bonnet has interesting proposal on how it should be done. I cannot be sure if this is correct as per the latest specifications but its interesting to learn how this would be done when the user moves out of coverage area in Idle or connected mode.

Note that this Expway paper also refers to Service continuity as Session continuity.

Related posts:

• Telstra's LTE-B Push
• Reliance Jio getting ready for LTE-Broadcast (eMBMS) rollout

enhanced Public Warning System (ePWS) in 3GPP Release-16

I wrote about PWS 9 years back here. Since then there has been little chance to PWS until recently. According to 3GPP News:

Additional requirements for an enhanced Public Warning System (ePWS) have been agreed at the recent 3GPP TSG SA#79 meeting, as an update to Technical Specification (TS) 22.268.

3GPP Public Warning Systems were first specified in Release 8, allowing for direct warnings to be sent to mobile users on conventional User Equipment (PWS-UE), capable of displaying a text-based and language-dependent Warning Notification.

Since that time, there has been a growth in the number of mobile devices with little or no user interface - including wrist bands, sensors and cameras – many of which are not able to display Warning Notifications. The recent growth in the number of IoT devices - not used by human users – also highlights the need for an alternative to text based Warning Notifications. If those devices can be made aware of the type of incident (e.g. a fire or flood) in some other way than with a text message, then they may take preventive actions (e.g. lift go to ground floor automatically).

3GPP SA1 delegates also considered how graphical symbols or images can now be used to better disseminate Warning Notifications, specifically aimed at the following categories of users:

• Users with disabilities who have UEs supporting assistive technologies beyond text assistive technologies; and
• Users who are not fluent in the language of the Warning Notifications.

Much of the work on enhancing the Public Warning System is set out in the ePWS requirements specification: TS 22.268 (SA1). You should also keep an eye on the 3GPP protocol specifications (CT1, Stage 3 work) in Release 16, covering:

• Specifying Message Identifiers for ePWS-UE, especially IoT devices that are intended for machine type communications
• Enabling language-independent content to be included in Warning Notifications

The work on ePWS in TS 22.268 (Release 16) is expected to help manufacturers of User Equipment meet any future regulatory requirements dedicated to such products.

Related Specs:

• 3GPP TR 22.869: Feasibility study on enhancements of Public Warning System; Stage 1
• 3GPP TS 22.268: Public Warning System (PWS) requirements - Stage 1 for Public Warning System
• 3GPP TS 23.041: Technical realization of Cell Broadcast Service (CBS) - CT1 aspects of Stage 3 for Public Warning System 
• 3GPP TS 29.168: Cell Broadcast Centre interfaces with the Evolved Packet Core; Stage 3 - CT4 aspects of Stage 3 for Public Warning System

Further reading:

• 3GPP: Towards a better Public Warning System (ePWS)
• 3G4G Blog: Public Warning System (PWS) in Release-9

The Rise and Rise or '4G' - Update on Release-11 & Release-12 features

A recent GSMA report suggests that China will be a significant player in the field of 4G with upto 900 million 4G users by 2020. This is not surprising as the largest operator, China Mobile wants to desperately move its user base to 4G. For 3G it was stuck with TD-SCDMA or the TDD LCR option. This 3G technology is not as good as its FDD variant, commonly known as UMTS.

This trend of migrating to 4G is not unique to China. A recent report (embedded below) by 4G Americas predicts that by the end of 2018, HSPA/HSPA+ would be the most popular technology whereas LTE would be making an impact with 1.3 Billion connected devices. The main reason for HSPA being so dominant is due to the fact that HSPA devices are mature and are available now. LTE devices, even though available are still slightly expensive. At the same time, operators are taking time having a seamless 4G coverage throughout the region. My guess would be that the number of devices that are 4G ready would be much higher than 1.3 Billion.

It is interesting to see that the number of 'Non-Smartphones' remain constant but at the same time, their share is going down. It would be useful to breakdown the number of Smartphones into 'Phablets' and 'non-Phablets' category.

Anyway, the 4G Americas report from which the information above is extracted contains lots of interesting details about Release-11 and Release-12 HSPA+ and LTE. The only problem I found is that its too long for most people to go through completely.

The whitepaper contains the following information:

3GPP Rel-11 standards for HSPA+ and LTE-Advanced were frozen in December 2012 with the core network protocols stable in December 2012 and Radio Access Network (RAN) protocols stable in March 2013. Key features detailed in the paper for Rel-11 include:

HSPA+:

• 8-carrier downlink operation (HSDPA)
• Downlink (DL) 4-branch Multiple Input Multiple Output (MIMO) antennas
• DL Multi-Flow Transmission
• Uplink (UL) dual antenna beamforming (both closed and open loop transmit diversity)
• UL MIMO with 64 Quadrature Amplitude Modulation (64-QAM)
• Several CELL_FACH (Forward Access Channel) state enhancements (for smartphone type traffic) and non-contiguous HSDPA Carrier Aggregation (CA)

LTE-Advanced:

• Carrier Aggregation (CA)
• Multimedia Broadcast Multicast Services (MBMS) and Self Organizing Networks (SON)
• Introduction to the Coordinated Multi-Point (CoMP) feature for enabling coordinated scheduling and/or beamforming
• Enhanced Physical Control Channel (EPDCCH)
• Further enhanced Inter-Cell Interference Coordination (FeICIC) for devices with interference cancellation

Finally, Rel-11 introduces several network and service related enhancements (most of which apply to both HSPA and LTE):

• Machine Type Communications (MTC)
• IP Multimedia Systems (IMS)
• Wi-Fi integration
• Home NodeB (HNB) and Home e-NodeB (HeNB)

3GPP started work on Rel-12 in December 2012 and an 18-month timeframe for completion was planned. The work continues into 2014 and areas that are still incomplete are carefully noted in the report.  Work will be ratified by June 2014 with the exception of RAN protocols which will be finalized by September 2014. Key features detailed in the paper for Rel-12 include:

HSPA+:

• Universal Mobile Telecommunication System (UMTS) Heterogeneous Networks (HetNet)
• Scalable UMTS Frequency Division Duplex (FDD) bandwidth
• Enhanced Uplink (EUL) enhancements
• Emergency warning for Universal Terrestrial Radio Access Network (UTRAN)
• HNB mobility
• HNB positioning for Universal Terrestrial Radio Access (UTRA)
• Machine Type Communications (MTC)
• Dedicated Channel (DCH) enhancements

LTE-Advanced:

• Active Antenna Systems (AAS)
• Downlink enhancements for MIMO antenna systems
• Small cell and femtocell enhancements
• Machine Type Communication (MTC)
• Proximity Service (ProSe)
• User Equipment (UE)
• Self-Optimizing Networks (SON)
• Heterogeneous Network (HetNet) mobility
• Multimedia Broadcast/Multicast Services (MBMS)
• Local Internet Protocol Access/Selected Internet Protocol Traffic Offload (LIPA/SIPTO)
• Enhanced International Mobile Telecommunications Advanced (eIMTA) and Frequency Division Duplex-Time Division Duplex Carrier Aggregation (FDD-TDD CA)

Work in Rel-12 also included features for network and services enhancements for MTC, public safety and Wi-Fi integration, system capacity and stability, Web Real-Time Communication (WebRTC), further network energy savings, multimedia and Policy and Charging Control (PCC) framework.

Whitepaper: 4G Mobile Broadband Evolution: 3GPP Release 11 & Release 12 and Beyond from Zahid Ghadialy

Access Class Barring in LTE using System Information Block Type 2

As per 3GPP TS 22.011 (Service accessibility):

All UEs are members of one out of ten randomly allocated mobile populations, defined as Access Classes (AC) 0 to 9. The population number is stored in the SIM/USIM. In addition, UEs may be members of one or more out of 5 special categories (Access Classes 11 to 15), also held in the SIM/USIM. These are allocated to specific high priority users as follows. (The enumeration is not meant as a priority sequence):
Class 15 - PLMN Staff;
 -"-  14 - Emergency Services;
 -"-  13 - Public Utilities (e.g. water/gas suppliers);
 -"-  12 - Security Services;
 -"-  11 - For PLMN Use.

Now, in case of an overload situation like emergency or congestion, the network may want to reduce the access overload in the cell. To reduce the access from the UE, the network modifies the SIB2 (SystemInformationBlockType2) that contains access barring related parameters as shown below:

For regular users with AC 0 – 9, their access is controlled by ac-BarringFactor and ac-BarringTime. The UE generates a random number
– “Rand” generated by the UE has to pass the “persistent” test in order for the UE to access. By setting ac-BarringFactor to a lower value, the access from regular user is restricted (UE must generate a “rand” that is lower than the threshold in order to access) while priority users with AC 11 – 15 can access without any restriction

For users initiating emergency calls (AC 10) their access is controlled by ac-BarringForEmergency – boolean value: barring or not

For UEs with AC 11- 15, their access is controlled by ac-BarringForSpecialAC - boolean value: barring or not.

The network (E-UTRAN) shall be able to support access control based on the type of access attempt (i.e. mobile originating data or mobile originating signalling), in which indications to the UEs are broadcasted to guide the behaviour of UE. E-UTRAN shall be able to form combinations of access control based on the type of access attempt e.g. mobile originating and mobile terminating, mobile originating, or location registration.  The ‘mean duration of access control’ and the barring rate are broadcasted for each type of access attempt (i.e. mobile originating data or mobile originating signalling).

Another type of Access Control is the Service Specific Access Control (SSAC) that we have seen here before. SSAC is used to apply independent access control for telephony services (MMTEL) for mobile originating session requests from idle-mode.

Access control for CSFB provides a mechanism to prohibit UEs to access E-UTRAN to perform CSFB. It minimizes service availability degradation (i.e. radio resource shortage, congestion of fallback network) caused by mass simultaneous mobile originating requests for CSFB and increases the availability of the E-UTRAN resources for UEs accessing other services.  When an operator determines that it is appropriate to apply access control for CSFB, the network may broadcast necessary information to provide access control for CSFB for each class to UEs in a specific area. The network shall be able to separately apply access control for CSFB, SSAC and enhanced Access control on E-UTRAN.

Finally, we have the Extended Access Barring (EAB) that I have already described here before.