Showing posts with label Release 16. Show all posts
Showing posts with label Release 16. Show all posts

Tuesday, 14 September 2021

3GPP Release 16 Description and Summary of Work Items


Someone reached out recently asking for a summary of Release 16 features. For people who are involved in standards, they already know of a few ways you can get this quickly. 

The first is to go to the Releases page here: https://www.3gpp.org/specifications/releases 

Here you can see the status of current releases as well as at the bottom of the page you can jump to the individual releases. 

A full Release Description is produced by the Work Plan manager at the completion of the work. This has been available since Release-14 onwards. You can go and get the latest version of the following technical reports:  

The following is the summary of features listed in 3GPP TR 21.916 for Release-16: 

  1. Enhancement of Ultra-Reliable and Low Latency Communications (URLLC)
    1. Enhancement of URLLC support in the 5G Core network
    2. Physical Layer Enhancements for NR Ultra-Reliable and Low Latency Communication (URLLC)
    3. Support of NR Industrial Internet of Things
  2. Support of LAN-type services
    1. NR-based access to unlicensed spectrum
    2. LAN support in 5G
    3. 5GS Enhanced support of Vertical and LAN Services
  3. Cellular Internet of Things (IoT)
    1. Cellular IoT support and evolution for the 5G System
    2. Additional enhancements for NB-IoT
    3. Additional MTC enhancements for LTE
  4. Advanced V2X support
    1. Improvement of V2X service Handling
    2. Architecture enhancements for 3GPP support of advanced V2X services
    3. Application layer support for V2X services
    4. 5G V2X with NR sidelink
  5. Northbound APIs related items
    1. Usage of CAPIF for xMB API
    2. Enhancement of 3GPP Northbound APIs
    3. Enhancements for Common API Framework for 3GPP Northbound APIs
    4. Service Enabler Architecture Layer for Verticals
    5. Other APIs-related items
  6. Coexistence with Non-3GPP systems
    1. Wireless and Wireline Convergence Enhancement
    2. Access Traffic Steering, Switch and Splitting support in the 5G system architecture
  7. Railways and Maritime
    1. Mobile Communication System for Railways 2
    2. Further performance enhancement for LTE in high speed scenario
    3. NR support for high speed train scenario
    4. Maritime Communication Services over 3GPP System
  8. Mission Critical, Public Warning
    1. Enhancements of Public Warning System
    2. MBMS APIs for Mission Critical Services
    3. Mission Critical Services Security Enhancements
    4. Other Mission critical improvements
      1. MCData File Distribution support over xMB
      2. Enhanced Mission Critical Communication Interworking with Land Mobile Radio Systems
      3. MBMS APIs for Mission Critical Services
      4. Enhancements to Functional architecture and information flows for Mission Critical Data
      5. MC Communication Interworking
      6. Enhanced Mission Critical Push-to-talk architecture phase 2
      7. Other Mission Critical activities
  9. Conversational services, Streaming and TV
    1. Conversational services
      1. Coverage and Handoff Enhancements for Multimedia (CHEM)
      2. Single radio voice continuity from 5GS to 3G
      3. Volume Based Charging Aspects for VoLTE
      4. EVS Floating-point Conformance for Non Bit-Exact
      5. Media Handling Extensions for 5G Conversational Services
      6. VR QoE metrics
      7. Media Handling Aspects of RAN Delay Budget Reporting in MTSI
      8. Removal of H.263 and MPEG-4 Visual from 3GPP Services
    2. 13.2 Streaming
      1. Enhancement of LTE for Efficient delivery of Streaming Service
      2. Enhancements to Framework for Live Uplink Streaming
      3. Media streaming architecture
  10. 5G Location and Positioning Services
    1. 5G positioning services (5G_HYPOS)
    2. Enhancement to the 5GC LoCation Services
    3. NR positioning support
  11. User Identities, Authentication, multi-device
    1. User Identities and Authentication
    2. Multi-device and multi-identity
  12. Slicing
    1. Enhancement of Network Slicing
    2. Enhancement of 3GPP management system for multiple tenant environment support
    3. Business Role Models for Network Slicing
    4. Enhancement of performance assurance for 5G networks including network slicing
  13. UE radio capability signalling optimization
    1. Optimisations on UE radio capability signalling
  14. Other system-wide Features
    1. Enablers for Network Automation Architecture for 5G
    2. Provision of Access to Restricted Local Operator Services by Unauthenticated UEs
    3. Enhancing Topology of SMF and UPF in 5G Networks
    4. Private and Non-Public Network Support for NG-RAN
    5. Service-Based Architecture
      1. Enhancements to the Service-Based 5G System Architecture
      2. SBA aspects of enhanced IMS to 5GC integration
    6. User data interworking, Coexistence and Migration
  15. Radio Features
    1. NR-related Release 16 Features
      1. NR-based access to unlicensed spectrum
      2. 2-step RACH for NR
      3. UE Power Saving in NR
      4. Integrated access and backhaul for NR
      5. Dual Connectivity (EN-DC) with 3 bands DL and 3 bands UL
      6. NR mobility enhancements
      7. Rel-16 NR inter-band CA/Dual Connectivity for 2 bands DL with x bands UL (x=1, 2)
      8. Rel16 NR inter-band Carrier Aggregation for 3 bands DL with 1 band UL
      9. Add support of NR DL 256QAM for frequency range 2 (FR2)
      10. SON (Self-Organising Networks) and MDT (Minimization of Drive Tests) support for NR
      11. Introduction of NR FDD bands with variable duplex and corresponding framework
      12. Cross Link Interference (CLI) handling and Remote Interference Management (RIM) for NR
      13. RF requirements for NR frequency range 1 (FR1)
      14. NR RF requirement enhancements for frequency range 2
      15. NR RRM enhancement
      16. RRM requirement for CSI-RS based L3 measurement in NR
      17. Over the air (OTA) base station (BS) testing TR
    2. Release 16 Features impacting both LTE and NR
      1. Transfer of Iuant interface specifications from 25-series to 37-series
      2. Introduction of GSM, UTRA, E-UTRA and NR capability set(s) (CS(s)) to the multi-standard radio (MSR) specifications
      3. Direct data forwarding between NG-RAN and E-UTRAN nodes for inter-system mobility
      4. eNB(s) Architecture Evolution for E-UTRAN and NG-RAN
      5. High power UE (power class 2) for EN-DC (1 LTE TDD band + 1 NR TDD band)
      6. LTE-NR & NR-NR Dual Connectivity and NR Carrier Aggregation enhancements
      7. 29 dBm UE Power Class for LTE band 41 and NR Band n41
      8. LTE/NR Dynamic Spectrum Sharing (DSS) in band 48/n48 frequency range
    3. LTE-related Release 16 Features
      1. LTE-based 5G terrestrial broadcast
      2. Support for NavIC Navigation Satellite System for LTE
      3. Even further mobility enhancement in E-UTRAN
      4. DL MIMO efficiency enhancements for LTE
      5. Other LTE-only items
  16. All other Release 16 Features
    1. Service Interactivity
    2. RTCP Verification for Real-Time Services
    3. Stage-3 SAE Protocol Development for Rel16
    4. Reliable Data Service Serialization Indication
    5. Shared Data Handling on Nudm and Nudr
    6. New Services and Markets Technology Enablers – Phase 2
    7. Ambient noise test methodology for evaluation of acoustic UE performance
    8. KPI reporting
  17. Telecom Management
    1. Network and Service Management
      1. 5G Management capabilities
      2. Energy Efficiency of 5G
      3. OAM aspects of LTE and WLAN integration
      4. Methodology for 5G management specifications
      5. Closed loop SLS Assurance
      6. Trace Management in the context of Services Based Management Architecture and Streaming Trace reporting
      7. Management of QoE measurement collection
      8. Network Resource Model (NRM) enhancement
    2. Charging Management
      1. Charging Enhancement of 5GC interworking with EPC
    3. Other charging and management items
  18. Other items
    1. Items not (fully) completed in Rel-16
      1. Remote Identification of Unmanned Aerial Systems
      2. 5G message service
      3. Integration of Satellite Access in 5G

If you find them useful then please get the latest document from here.

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Tuesday, 7 September 2021

Future Railway Mobile Communication System (FRMCS)


I have been meaning to write on this topic for a very long time. The discussion started back in 2016 when the limitations of GSM-R were obvious and it was recognised that a successor will be needed sooner or later. The International Railway Union (UIC) published a user requirement specification in their paper “Future Railway Mobile Communication System - FRMCS”. This is available on 3GPP server as liaison statement S1-161250.

As 3GPP notes in their article, this was the trigger for them to go ahead and start the studies. Then in Release 16, 3GPP TS 22.289 "Mobile communication system for railways" outlined the requirements for railway communication, beyond the 3GPP Future Railway Mobile Communication System (FRMCS) Phase 1 specs. Details are available on this post here.

Source Tweet

The latest version of 3GPP TR 22.889, Study on Future Railway Mobile Communication System; Stage 1 is from Release 17. The introduction to the document clarifies:

The railway community is considering a successor communication system to GSM-R, as the forecasted obsolescence of the 2G-based GSM-R technology is envisaged around 2030, with first FRMCS trial implementations expected to start around 2020. 

The Future Railway Mobile Communication System (FRMCS) Functional Working Group (FWG) of the International Union of Railways (UIC) have investigated and summarised their requirements for the next generation railway communication system in the Future Railway Mobile Communication User Requirements Specification (FRMCS URS). The present document is based on this input given by the UIC/ETSI TC-RT 

Study on FRMCS Evolution (FS_eFRMCS), available as SP-201038 clarifies:

The UIC FRMCS programme was recently releasing stable version 5.0.0 of the User Requirement Specification, version 2.0.0 of the Functional Use Cases and a new specification item, version 1.0.0 of the Telecom On-Board System - Functional Requirements Specification, as a further step in the evolution of the FRMCS specifications. The UIC FRMCS Programme is developing all the technical conditions for the 5G FRMCS, with the main objective to make available a “FRMCS First Edition” ecosystem available for procurement by Q1 2025.

The UIC FRMCS 3GPP Task Force has been identifying and analyzing impact of this newly released set of FRMCS specifications on existing use cases and requirements collected in TR 22.889. The UIC FRMCS 3GPP Task Force analysis has concluded that refining existing use cases, defining new use cases such as merging railway emergency communications and real-time translation of conversation, and deriving potential new requirements, will be necessary to align FRMCS and 3GPP specifications. The potential impact on normative work is estimated to be limited and much less compared to the study work.

As approved in SA1#90-e (S1-202245), TR 22.889 has now been re-named to TR 22.989 from Rel-18 onwards (latest version is TR 22.989 v18.0.0) to make it visible to the Rail community to be able to follow the 3GPP normative work in line with their needs. It is of most importance for the Rail community that specifications from different organisations (i.e. UIC, 3GPP and ETSI) are all aligned.

Due to the expected 3GPP work overload in Release 18 (SA1 and downstream groups), it is proposed to reduce the scope of the present Rel-18 study to evolution of critical applications related use cases only already identified by UIC – what is really essential for the railways as part of the “FRMCS First Edition” and the migration phase from GSM-R to FRMCS. 

Study of non-essential use cases (e.g. evolution of performance and business use cases) shall be postponed to Rel-19.

This plan is from 2019 so quite likely that it is already outdated. It does provide an idea on different steps and trial plans. Some of this was also covered in the 5G RAN Release 18 for Industry Verticals Webinar detailed here.

Finally, as this image from Arthur D. Little highlights, there is a lot of other interest in addition to FRMCS for 5G in railway. Report here.

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Wednesday, 1 September 2021

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.

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Monday, 31 May 2021

5G User Plane Redundancy


We looked at the 5G Enhanced URLLC (eURLLC) earlier. One of the ways to improve reliability is to have redundancy in the user plane. This can use different approaches like: 

  • Duplicating N3
  • Adding a secondary gNB using Dual connectivity
  • Introducing another UPF
  • Two anchor UPFs

In fact they are all built on top of each other so you can decide how critical are your user plane redundancy needs. 

I came across this short video from Mpirical embedded below that covers this topic nicely. In case you want to refresh your 5G Core Network architecture, jump to our old tutorial here.

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Monday, 12 April 2021

Positioning in 5G networks



I have written about the 5G positioning techniques not that long back on this blog here and on connectivity technology blog here. With Release-16 now ready for deployment, Huawei has already announced world's first in 5G Indoor Positioning. Their announcement said:

China Mobile Suzhou and Huawei reached a new milestone with the verification of the 5G indoor positioning capability in metro transport scenarios in Suzhou — a major city located along the southeastern edge of Jiangsu Province in eastern China. The verification showed that, even with pRRUs being hidden, a positioning precision of 3 to 5 m can be achieved in 90% of the platform and hall areas. This is the first time that 5G indoor positioning has been verified on live networks in the world, providing valuable experience for the commercial growth of 5G positioning in vertical industries.

Indoor location-based services are in high demand of vertical applications, such as indoor navigation, asset tracking, geofencing, logistics management, and personnel management, which reflects the huge market space of indoor positioning. Currently, indoor positioning technologies are of great variety and most of them need to be deployed and maintained individually, resulting in high end-to-end costs. As a part of the continuous evolution of 5G, positioning has been added to 3GPP Release 16 finalized in mid 2020 to realize indoor positioning by leveraging the ultra-high signal resolution empowered by 5G's high bandwidth, multi-point measurements, and multi-access edge computing (MEC) deployment.

The verification was based on Huawei's 5G digital indoor solution LampSite and leading MEC solution. The LampSite units measure the radio signals of 5G devices and work with MEC to analyze the signal characteristics. Based on the results of the analysis, leading algorithms are used to precisely locate 5G devices.

We wrote about Huawei's Lampsite on Telecoms Infrastructure blog last year here.

A group of Ericsson engineers have written a research paper on 5G positioning recently. It's available on arXiv here. Here is the abstract:

In this paper we describe the recent 3GPP Release 16 specification for positioning in 5G networks. It specifies positioning signals, measurements, procedures, and architecture to meet requirements from a plethora of regulatory, commercial and industrial use cases. 5G thereby significantly extends positioning capabilities compared to what was possible with LTE. The indicative positioning performance is evaluated in agreed representative 3GPP simulation scenarios, showing a 90 percentile accuracy of a few meters down to a few decimeters depending on scenarios and assumptions.

Definitely worth a read if you like hardcore technical papers.

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Wednesday, 10 March 2021

Everything you need to know about 5G Security


5G & Security are both big topics on this blog as well as on 3G4G website. We reached out to 3GPP 5G security by experts from wenovator, Dr. Anand R. Prasad & Hans Christian Rudolph to help out audience understand the mysteries of 5G security. Embedded below is video and slides from a webinar they recorded for us.

You can ask any security questions you may have on the video on YouTube

The slides could be downloaded from SlideShare.

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Tuesday, 2 February 2021

NWDAF in 3GPP Release-16 and Release-17

We looked at Network Data Analytics Function, NWDAF, in detail here. While the 3GPP Release-16 work just starting back then, we have now completed Rel-16 and looking at Release 17. 

The 5G Core (5GC) supports the application of analytics to provide Intelligent Automation of the network, In Rel-16 the set of use cases that are proposed for the NWDAF has been widely expanded. 

In an earlier post, we looked at the ATIS webinar discussing Release-16 & forthcoming features in Rel-17. Puneet Jain, Director of Technical Standards at Intel and 3GPP SA2 Chairman talked briefly about NWDAF. The following is from his talk:

Release-16 provides support for Network Automation and Data Analytics.  Network Data Analytics Function (NWDAF) was defined to provide analytics to 5G Core Network Functions (NFs) and to O&M. It consists of several services that were defined in 3GPP Rel-16 and work is now going in Release 17 to further extend them. 

In release 16 Slice load level related network data analytics and observed service experience related network data analytics were defined. NF load analytics as well Network Performance analytics was also specified. NWDAF provides either statistics or prediction on the load communication and mobility performance in the area of interest. 

Other thing was about the UE related analytics which includes UE mobility analytics, UE communication analytics, Expected UE behavior parameter, Related network data analytics and abnormal behavior related network data analytics.

The NWDAF can also provide user data congestion related analytics. This can be done by one time reporting or continuous reporting in the form of statistics or prediction or both to any other network function. 

QoS sustainability analytics, this is where the consumer of QoS sustainability analytics may request NWDAF analytics information regarding the QoS change statistic for a specific period in the past in a certain area or the likelihood of QoS change for a specific period in future, in certain areas. 

In Release 17, studies are ongoing for network automation phase 2. This includes some leftover from Release 16 such as UE driven analytics, how to ensure that slice SLA is guaranteed and then also new functionality is being discussed that includes things like support for multiple NWDAF instance in one PLMN including hierarchies, how to enable real-time or near-real-time NWDAF communications, how to enable NWDAF assisted user pane optimization and last which is very interesting is about interaction between NWDAF and AI model and training service owned by the operator.

This article on TM Forum talks about NWDAF deployment challenges and recommendations:

To deploy NWDAF, CSPs may encounter these challenges:

  • Some network function vendors may not be standards compliant or have interfaces to provide data or receive analytics services.
  • Integrating NWDAF with existing analytics applications until a 4G network is deployed is crucial as aggregated network data is needed to make decisions for centralized analytics use cases.
  • Many CSPs have different analytics nodes deployed for various use cases like revenue assurance, subscriber/marketing analytics and subscriber experience/network management. Making these all integrated into one analytics node also serving NWDAF use cases is key to deriving better insights and value out of network data.
  • Ensuring the analytics function deployed is integrated to derive value (e.g., with orchestrator for network automation, BI tools/any UI/email/notification apps for reporting).

Here are some ways you can overcome these challenges and deploy efficient next-generation analytics with NWDAF:

  • Mandate a distributed architecture for analytics too, this reduces network bandwidth overhead due to analytics and helps real-time use cases by design.
  • Ensure RFPs and your chosen vendors for network functions have, or plan to have, NWDAF support for collecting and receiving analytics services.
  • Look for carrier-grade analytics solutions with five nines SLAs.
  • Choose modular analytics systems that can accommodate multiple use cases including NWDAF as apps and support quick development.
  • Resource-efficient solutions are critical for on-premise or cloud as they can decrease expenses considerably.
  • Storage comes with a cost, store more processed smart data and not more raw big data unless mandated by law.
  • In designing an analytics use case, get opinions from both telco and analytics experts, or ideally an expert in both, as they are viewed from different worlds and are evolving a lot.

This is such an important topic that you will hear more about it on this blog and elsewhere.

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Friday, 15 January 2021

UE Radio Capability Signaling Optimization (RACS) in Rel. 16

The data volume of UE Radio Capability Information defined in 3GPP 38.306 is already high and will further increase starting with Rel. 16 due to additional supported bands and other features.

Due to this 3GPP has standardized in Release 16 what is called UE Radio Capability Signaling Optimization (RACS) for both, E-UTRAN/EPS and NG RAN/NGC networks. 

Release 16 RACS does not apply to NB-IoT.

The first key element of this feature set is the introduction of a new UE Radio Capability ID that is structured as defined in 3GPP 23.003 and shown in figure 1 below:

UE Radio Capability ID
Figure 1: UE Radio Capability ID according to 3GPP 23.003

The components of this new ID are:

  •    TF - Type Field (TF): identifies the type of UE radio capability ID.
            Type = 0 -> manufacturer-assigned UE radio capability ID
            Type = 1 -> network-assigned UE radio capability ID

  •  The Version ID configured by the UE Capability Management Function (UCMF) that is part of the EPS/5GC. The Version ID value makes it possible to detect whether a UE Radio Capability ID is current or outdated.

·      The Radio Configuration Identifier (RCI) identifies the UE radio configuration.

The PLMN-assigned UE Radio Capability ID is assigned to the UE using the Non-Access Stratum UE Configuration Update Command or Registration Accept message (figure 2).

Figure 2: PLMN-assigned UE Radio Capability Update according to 3GPP 23.743

The new UCMF (UE radio Capability Management Function) stores All UE Radio Capability ID mappings in a PLMN and is responsible for assigning every PLMN-assigned UE Radio Capability ID.

Due to introduction of the UMCM in the core networks the new Nucmf service-based interface is defined for the 5GC and new S17 reference point is defined for the EPS as shown in figure 3.

Figure 3: Network Architecture with UCMF according to 3GPP 21.916

Each UE Radio Capability ID stored in the UCMF can be associated to one or both UE radio capabilities formats specified in 3GPP TS 36.331 [LTE RRC] and 3GPP TS 38.331 [NR RRC]. The AMF must only be able ot handle the NR RRC format while the MME uses the LTE RRC format. Which format is required by the UCMF is configurable.

If at any time the AMF/MME has neither a valid UE Radio Capability ID nor any stored UE radio capabilities for the UE, the AMF/MME may trigger the RAN to provide the UE Radio Capability information and subsequently request the UCMF to allocate a UE Radio Capability ID.

In NG RAN the UE Capability Request can be requested by the AMF as a flag in any NGAP Downlink NAS Transport message or by sending a NGAP UE Radio Capability Check Request (for checking compatibility of IMS voice capabilities). This triggers a NR RRC UE Capability Transfer procedure and subsequently NGAP UE Radio Capability Info Indication or NGAP UE Radio Capability Check Response (for IMS voice support parameters).

Using the NGAP UE Capability ID Mapping procedure the NG RAN node is able to request the most recent UE Capability ID mapping information from the core network functions AMF/UCMF. The same functionality is implemented in S1AP for signaling between eNB and MME/UCMF.

If the volume of the LTE/NR RRC UE Capability to be sent by the UE is larger than the maximum supported size of a PDCP SDU (specified in 3GPP 38.323) then the UE Capability Info can be transported in LTE/NR RRC using a chain of UL Dedicated Message Segment messages.

Figure 4: RRC UL Dedicated Segment Message transporting UE Radio Capability Information according to 3GPP 36.331 and 38.331

Each of these message will have a dedicated segment number and the last one has the rrc-MessageSegmentType =  “lastSegment”, which triggers reassembly of the orignal UE Capabability information in the receiving entity.

Thursday, 17 December 2020

Conditional Handover (Rel. 16) Explained

Although a couple of SON mobility robustness features have been introduced in LTE radio networks it is still a common problem in some network areas that a high number of handover failures leads to higher drop rates and large numbers of RRC Re-Establishments.

Often these problems occur due to quickly changing radio conditions in the handover preparation phase or after handover execution attempt. 

SON algorithms cannot cope with these dynamic changes of the environment, but improvement is possible if the UE itself is enabled to constantly monitor the radio quality during the handover procedure and finally select the best possible target cell from a list of candidate neighbors. This new feature defined in 3GPP Release 16 for both, NG RAN (5G SA NR) as well as E-UTRAN (LTE), is called "Conditional Handover". The figure below illustrates how it works.

(click on the picture to enlarge)

Step 1 is the RRC Measurement Report indicating that handover to a neighbor cell is required. However, this message contains a list of candidate neighbor cells.

In the figure it is assumed that each of these candidate cells is controlled by a different gNB. Hence, 3 XnAP Handover Preparation procedures are performed and each potential target gNB allocates radio resources for the UE and provides a handover command (NR RRC Reconfiguration message) that is sent back to the source gNB (step 2).

In step 3 the source gNB builds the conditional handover command, which is a NR RRC Reconfiguration message that contains a list of conditional reconfiguration options plus additional RRC measurement configurations that enable the UE to find out which of the possible target cells is the best fit. 

In step 4 the UE makes its handover decision and moves to the cell controlled by target gNB 1.

Here it sends in step 5 the NR RRC Reconfiguration Complete message. 

The target gNB 1 detects the handover completion based on the reception of the NR RRC Reconfiguration Complete message, performs NGAP Path Switch procedure (not shown in figure) and triggers the release of the UE context in source gNB on behalf of sending the XnAP UE Context Release message (step 6).

With this information the source gNB also detects the successful handover completion and orders in step 7 the release of the radio resources provided by target gNB 2 and 3 to which it sends the new XnAP Conditional Handover Cancel message.

As mentioned before the conditional handover is also possible for LTE radio connections. In this case X2AP is used instead of XnAP and LTE RRC instead of NR RRC.

The conditional handover can be performed for all kind of intra-eNB/gNB handover and X2/Xn handover. However, S1/N2 (NG-C) conditional handover is not allowed.


Monday, 30 November 2020

Three New Standards to Accelerate 5G Wireless Wireline Convergence (WWC)

It's been just over a year since I wrote a detailed post on what I called '5G and Fixed-Mobile Convergence (FMC)'. The technical term being used in the industry for this feature is Wireless Wireline Convergence (WWC). 

Broadband Forum, the communications industry’s leading open standards development organization focused on accelerating broadband innovation, standards, and ecosystem development has just announced the publication of three new standards to accelerate global 5G adoption. The press release said:

Building on the Forum’s mission to drive a future consolidated approach to 5G, the standards will reduce development time, as well as capex and opex, from the traditional disparate fixed broadband and 5G networks. Ultimately, they will deliver a common and managed broadband experience to the end-user whatever the final connectivity technology.

There are three major sets of technical specifications that have been finalized, including 5G Wireless Wireline Convergence Architecture (TR-470), Access Gateway Function (AGF) Functional Requirements (TR-456) and Device Data Model (TR-181). Together, these documents provide functions and interfaces for Fixed Mobile Convergence (FMC), the AGF, and customer premises equipment (CPE) such as 5G-enabled routers.

TR-470 – produced in conjunction with 3GPP – describes the 5G FMC architecture, providing a high-level guide for network architects and planners and enabling fixed and mobile functions to coexist over a shared infrastructure. This will facilitate multi-access connectivity and give consumers a seamless, access-independent service experience.


For operators, the network functions required to operate their infrastructure will be streamlined and common technology, on-boarding, training, services and subscriber management between fixed and mobile divisions can be achieved. Furthermore, additional revenue streams will be created, with FMC extending the geographical reach of 5G core networks and the service offering of fixed networks.

TR-456 describes the functional requirements of the AGF. The AGF resides between fixed access networks and the 5G core network to support 5G and wireline Residential Gateways, creating a truly converged deployment. Alongside this, Broadband Forum’s Device: 2 data model (TR-181 Issue 2 Amendment 14), which is used by User Services Platform (USP), has been extended to address 5G Residential Gateways. The Device: 2 data model applies to all types of TR-069 or USP-enabled devices, including end devices, Residential Gateways, and other network infrastructure devices

In addition, the Functional Requirements for Broadband Residential Gateway Devices (TR-124) specification is expected to be finalized in Q4 2020. Moving from the network into the home, TR-124 has been extended to add requirements related to the 5G Residential Gateway extending the 5G control plane to the premises to open up new service opportunities with real time fulfillment.

In the video below, David Allan, Work Area Director for Wireless-Wireline Convergence at Broadband Forum and Christele Bouchat, Innovation Group Director at Broadband Forum discuss what is coming up in the next phase of 5G work and what opportunities this has opened up for the industry

WWC has a great potential to allow wireline and trusted/untrusted Wi-Fi to work with 5G so I am hopeful that operators will adopt this sooner, rather than later.

Follow the links below to learn more about this feature.

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Friday, 20 November 2020

Business Role Models for Network Slicing and iRAT Mobility for Cellular Internet of Things (CIoT) in Release 16

 3GPP Release 16 describes business role models for network slicing and in TR 21.916 I found the figures below that I have pimped a little bit to illustrate an asset tracking use case for goods transported with a truck from Factory A to Factory B. 

Factory B is equipped with a 5G Non-Public Network (NPN) that broadcasts an NPN-ID or - if the network infrastructure is deployed by an operator - a Cell Access Group ID (CAG ID).

I would like to assume that in case of the scenario shown in 3GPP Figure 2-2 the asset tracking CIoT devices are able to access any necessary PLMN, Network Slice and NPN. This can be achieved e.g. by using an eSIM. 

So while the truck is at the location of Factory A the asset tracking "things" will connect to the private slice of Factory A provided by the operator of PLMN 1. Factory A is a tenant of this operator. This means: Factory A rented a virtual part of PLMN1 for private use and technically this rented virtual network part is realized by a NW slice. 

When the truck leaves Factory A and drives on the road (maybe a long distance) to Factory B the asset tracking data must be transmitted over public mobile network infrastructure. Depending on rural coverage this service can be offered by PLMN 2 (as in case of 3GPP figure 2-2) or by PLMN 1 (as in case of 3GPP figure 2-3).

In case of 3GPP figure 2-4 the operator of PLMN 1 is even able to provide the private slice along the road, which allows Factory A to stretch the coverage of their virtual private network (slice) over a very long distance.

Looking further into the Cellular IoT enhancements defined by 3GPP in Release 16 it turns out that actually there is no need for a nation-wide 5G coverage to realize at least the role models shown in the 3GPP figures 2-2 and 2-3.

Because Release 16 also defines co-existence and inter-RAT mobility between 5G CIoT traffic and 4G NB-IoT the operators of PLMN 1 and PLMN 2 may offer NB-IoT coverage along the road while the factories are covered with 5G NR frequency cells - as shown in my second figure below.  

It illustrates the great improved flexibility that Release 16 standards are offering for customized business solutions and monitoring the service quality is not a trivial task under these circumstances.  


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Friday, 23 October 2020

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 hereRelease 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. 


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Wednesday, 7 October 2020

Understanding the Dual Active Protocol Stack (DAPS) Handover in 5G


In this video I explain the principles and signaling procedures related to the DAPS handover.

The DAPS handover is a new feature for URLLC services defined by 3GPP in Rel. 16.

Friday, 2 October 2020

5G Enhanced URLLC (eURLLC)

One of the interesting features of 5G is Ultra-Reliability and Low-Latency Communication or URLLC. It has been enhanced as part of 3GPP Release-16. A summary of the changes in eURLLC can be seen in the picture above. 


This ATIS webinar that I blogged about last week covered this topic as well. For example L1/L2 changes have been summarised nicely in this Qualcomm slide above while the slide from Intel speaker below looks at redundant transmission and session continuity.

Redundant transmission in the user plane is an extremely useful feature, especially if the packets are mission critical and have to reach from the source to their destination in a guaranteed time / reliability.

Dual connectivity will enable this redundant path when required to meet a guaranteed reliability. 

Here is a short video from the training company Mpirical, explaining the the 5G eURLLC feature: 

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Sunday, 27 September 2020

ATIS Webinar on '5G Standards Developments in 3GPP Release 16 and Beyond'

3GPP Organizational Partner, ATIS (Alliance for Telecommunications Industry Solutions), recently delivered a webinar (video & slides below) titled "5G Standards Developments in 3GPP Release 16 and Beyond". 

3GPP News details:

An expert panel brings you up-to-speed on the current state of 5G standardization. The webinar delivers a broad overview of 3GPP's work and introduces some of the key technology elements. It is suitable for people in technical roles and technical executives who want to understand the current state of 5G standardization.

In Release 16, 3GPP delivered important updates to 5G specifications to broaden their range of commercial applications and improve the efficiency of networks. 3GPP is now further enhancing 5G in Release 17 and starting to plan Release 18. This webinar provides an up-to-date view of the completed 3GPP Release 16 work with a particular focus on how the work is expanding capabilities of 5G and enhancing the technical performance of the mobile system. It also looks ahead to future 3GPP deliverables and their use cases.


The webinar features, Iain Sharp, Principal Technologist at ATIS (Moderator), Greg Schumacher, Global Standards at T-Mobile USA and 3GPP SA and SA1 Vice Chairman, Puneet Jain, Director of Technical Standards at Intel and 3GPP SA2 Chairman and Wanshi Chen, Senior Director, Technology at Qualcomm and 3GPP RAN1 Chairman


Many interesting topics have been covered including the updates on mMTC and URLLC. 


There is also details about new features coming in 3GPP Release-17 and an early look at what 3GPP Release-18 might include, as can be seen in the picture above.

Thursday, 10 September 2020

Interfacing HSS and UDM in 5GS with UDICOM (a.k.a NU1 / Nhss)

Back in 2012, we were talking about migration from HLR to HSS. Now we are discussing how to interface HSS to the UDM (Unified Data Management in 5G Core).


In the recent 5G World event, Richard Band, Head of 5G Core, HPE talked about 4G to 5G transition planning. During the talk he mentioned about UDICOM, which is the Standardised new interface between HSS and UDM as defined in 3GPP TS 23.632.


UDICOM allows operators to deploy separate HSS and UDM, even from different vendors. Supported features include:
  • Authentication
  • Single Registration Handover
  • IMS
  • SMS over NAS
3GPP TS 23.632 (Technical Specification Group Core Network and Terminals; User data interworking, coexistence and migration; Stage 2; Release 16) does not use the term UDICOM. It does however describe the interface details, system architecture, system procedures and network function service procedures of UDM-HSS interface.

As can be seen in the picture above, the following reference points are realized by service-based interfaces:
NU1: Reference point between the HSS and the UDM.
NU2: Reference point between the HSS and the 5GS-UDR.

The following Service based interfaces are defined for direct UDM-HSS interworking:
Nudm: Service-based interface exhibited by UDM.
Nhss: Service-based interface exhibited by HSS.

I am not going in more details here but anyone wanting to learn more about the interface should start with 3GPP TS 23.632.

Finally, this talk from HP Enterprise below provides more details of UDICOM.



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