How Multiband-Cells are used for MORAN RAN Sharing

In the previous blog post I have explained the concept of multi-band cells in LTE networks and promised to explain a bit deeper how such cells can be used in Multi-Operator RAN (MORAN) scenarios. 

MORAN is characterized by the fact that all network resources except the radio carriers and the Home Subscriber Server (HSS) are shared between two or more operators. 

What this means in detail can be see in Step 1 of the figure below. 

The yellow Band #1 spectrum of the multi-band cell is owned by Network Operator 1 while the blue spectrum of Band #2 and Band #3 belongs to Network Operator 2.

Band #1 is the default band. This means if a UE enters the cell is always has to establish the initial RRC signaling connection on Band #1 as shown in step 1.

The spectrum owned by Network Operator 2 comes into the game as soon as a dedicated radio bearer (DRB), in the core network known as E-RAB, is established in this RRC connection. 

Then we see intra-frequency (intra-cell) handover to Band #2 where the RRC signaling connection is continued. Band #3 is added for user plane transport as a secondary "cell" (the term refers to the 3GPP 36.331 RRC specification). 

The reason for this behavior can be explained when looking a frequency bandwidths. 

The default Band #1 is a low frequency band with a quite small bandwidth, e.g. 5 MHz. as it is typically used for providing good coverage in rural areas. Band #2 is also a lower frequency band, but Band #3 is a high frequency band with maximum bandwidth of 20 MHz. So Band #3 brings the highest capacity for user plane transport and that is the reason for the handover to the spectrum owned by Network Operator 2 and the carrier aggregation used on these frequency bands. 

However, due to the higher frequency the footprint of Band #3 is lower compared to the other two frequency bands. 

For UEs at the cell edge (or located in buildings while being served from the outdoor cell) this leads quite often to situations where the radio coverage of Band #3 becomes insufficient. In such cases the UE typically sends a RRC measurement event A2 (means: "The RSRP of the cell is below a certain threshold."). 

If such A2 event is received by the eNB it stops the carrier aggregation transport and releases the Band #3 resources so that all user plane transport continues to run on the limited Band #2 resources as shown in step 3.

And now in the particular eNB I observed a nice algorithm starts that could be seen as a kind of zero-touch network operation although it does not need big data nor artificial intelligence. 

10 seconds after the secondary frequency resources of Band #3 have been deleted they are added again to the connection, but if the UE is still at the same location the next A2 will be reported soon and carrier aggregation will be stopped again for 10 seconds and then the next cycle starts.

This automation loop is carried out endlessly until the UE changes its location or the RRC connection is terminated. 

Related Posts:

• The 3G4G Blog: What is a Multi-Band Cell? 

DCCA Features and Enhancements in 5G New Radio

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

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

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

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

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

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

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

The table below summarizes the DCCA features in 5G NR

Related Posts: 

• The 3G4G Blog: ATIS Webinar on '5G Standards Development Update in 3GPP Release 17 and 18'
• The 3G4G Blog: 3GPP's 5G-Advanced Workshop Summary
• The 3G4G Blog: What Is the Role of AI and ML in the Open RAN and 5G Future?
• The 3G4G Blog: Conditional Handover (Rel. 16) Explained
• The 3G4G Blog: Understanding the Dual Active Protocol Stack (DAPS) Handover in 5G
• Free 6G Training: Deep Learning in the 6G Air Interface
• Free 6G Training: Kyocera Develops Transmissive Metasurface Technology for B5G and 6G
• Free 6G Training: 6G and B5G Prospects for Vertical Industry
• Free 6G Training: The Potential of Full Duplex in Beyond 5G and 6G
• Free 6G Training: Using a Dielectric Waveguide as a Pinching Antenna for B5G and 6G 

Managing 5G Signalling Storms with Service Communication Proxy (SCP)

When we made our 5G Service Based Architecture (SBA) tutorial some four years back, it was based on Release-15 of the 3GPP standards. All Network Functions (NFs) simply sent discovery requests to the Network Repository Function (NRF). While this works great for trials and small scale deployments it can also lead to issues as can be seen in the slide above.

In 3GPP Release-16 the Service Communication Proxy (SCP) has now been introduced to allow the Control Plane network to handle and prioritize massive numbers of requests in real time. The SCP becomes the control point that mediates all Signalling and Control Plane messages in the network core.

SCP routing directs the flow of millions of simultaneous 5G function requests and responses for network slicing, microservice instantiation or edge compute access. It also plays a critical role in optimizing floods of discovery requests to the NRF and in overall Control Plane load balancing, traffic prioritization and message management.

A detailed whitepaper on '5G Signaling and Control Plane Traffic Depends on Service Communications Proxy (SCP)' by Strategy Analytics is available on Huawei's website here. This report was a follow on from the 'Signaling — The Critical Nerve Center of 5G Networks' webinar here.

Related Posts:

• 3G4G: 5G Service Based Architecture (SBA)
• The 3G4G Blog: Interfacing HSS and UDM in 5GS with UDICOM (a.k.a NU1 / Nhss)
• The 3G4G Blog: 5G Roaming with SEPP (Security Edge Protection Proxy)
• The 3G4G Blog: Everything you need to know about 5G Security
• 3G4G: 3GPP 5G Specifications

AI/ML Enhancements in 5G-Advanced for Intelligent Network Automation

Artificial Intelligence (AI) and Machine Learning (ML) has been touted to automate the network and simplify the identification and debug of issues that will arise with increasing network complexity. For this reason 3GPP has many different features that are already present in Release-17 but are expected to evolve further in Release-18. 

I have already covered some of this topics in earlier posts. Ericsson's recent whitepaper '5G Advanced: Evolution towards 6G' also has a good summary on this topic. Here is an extract from that:

Intelligent network automation

With increasing complexity in network design, for example, many different deployment and usage options, conventional approaches will not be able to provide swift solutions in many cases. It is well understood that manually reconfiguring cellular communications systems could be inefficient and costly.

Artificial intelligence (AI) and machine learning (ML) have the capability to solve complex and unstructured network problems by using a large amount of data collected from wireless networks. Thus, there has been a lot of attention lately on utilizing AI/ML-based solutions to improve network performance and hence providing avenues for inserting intelligence in network operations.

AI model design, optimization, and life-cycle management rely heavily on data. A wireless network can collect a large amount of data as part of its normal operations. This provides a good base for designing intelligent network solutions. 5G Advanced addresses how to optimize the standardized interfaces for data collection while leaving the automation functionality, for example, training and inference up to the proprietary implementation to support full flexibility in the automation of the network.

AI/ML for RAN enhancements

Three use cases have been identified in the Release 17 study item related to RAN performance enhancement by using AI/ML techniques. Selected use cases from the Release 17 technical report will be taken into the normative phase in the next releases. The selected use cases are: 1) network energy saving; 2) load balancing; and 3) mobility optimization.

The selected use cases can be supported by enhancements to current NR interfaces, targeting performance improvements using AI/ML functionality in the RAN while maintaining the 5G NR architecture. One of the goals is to ensure vendor incentives in terms of innovation and competitiveness by keeping the AI model implementation specific. As shown in Fig.2 (on the top) an intent-based management approach can be adopted for use cases involving RAN-OAM interactions. The intent will be received by the RAN. The RAN will need to understand the intent and trigger certain functionalities as a result.

Ericsson White Paper - 5G Advanced: Evolution towards 6G - https://t.co/9ZKnC8PDxX#Free5Gtraining #Ericsson #5G #B5G #5GAdvanced #6G #5GNR #5GC #Timeline #XR #RedCap #NetworkAutomation #EnergySavings #DeterministicNetworking #IoT pic.twitter.com/eeI4SKvIRC

— Free 5G Training (@5Gtraining) July 21, 2022

AI/ML for physical layer enhancements

It is generally expected that AI/ML functionality can be used to improve the radio performance and/or reduced the complexity/overhead of the radio interface. 3GPP TSG RAN has selected three use cases to study the potential air interface performance improvements through AI/ML techniques, such as beam management, channel state information feedback enhancement, and positioning accuracy enhancements for different scenarios. The AI/ML-based methods may provide benefits compared to traditional methods in the radio interface. The challenge will be to define a unified AI/ML framework for the air interface by adequate AI/ML model characterization using various levels of collaboration between gNB and UE.

AI/ML in 5G core

5G Advanced will provide further enhancements of the architecture for analytics and on ML model life-cycle management, for example, to improve correctness of the models. The advancements in the architecture for analytics and data collection serve as a good foundation for AI/ML-based use cases within the different network functions (NFs). Additional use cases will be studied where NFs make use of analytics with the target to support in their decision making, for example, network data analytics functions (NWDAF)- assisted generation of UE policy for network slicing.

If you are interested in studying this topic further, check out 3GPP TR 37.817: Study on enhancement for data collection for NR and ENDC. Download the latest version from here.

Related Posts: 

• The 3G4G Blog: What Is the Role of AI and ML in the Open RAN and 5G Future?
• The 3G4G Blog: 3GPP Release-18 Work Moves Into Focus as Release-17 Reaches Maturity
• The 3G4G Blog: NWDAF in 3GPP Release-16 and Release-17
• The 3G4G Blog: 5G-Advanced Flagship Features
• The 3G4G Blog: 3GPP's 5G-Advanced Technology Evolution from a Network Perspective Whitepaper
• Free 6G Training: Qualcomm Pushing the boundaries of AI research 

GSMAi Webinar: Is the Industry Moving Fast Enough on Standalone 5G?

I recently participated in a webinar, discussing one of my favourite topics, 5G Standalone (5G SA). If you do not know about 5G SA, you may want to quickly watch my short and simple video on the topic here.

Next week I am participating in a webinar, "Open for Debate: Is the Industry Moving Fast Enough on Standalone 5G?" along with Peter Jarich, Radhika Gupta and Tim Hatt. Hope to see you there: https://t.co/TQ8Aa5LXYP #3G4G5G #5G #5GNetworks #5GTechnology #5GNR #5GStandalone #5GSA pic.twitter.com/Rd7hGvvCNe

— Zahid Ghadialy (@zahidtg) July 15, 2022

Last year I blogged about GSA's 5G Standalone webinar here. That time we were discussing why 5G SA is taking time to deliver, it was sort of a similar story this time. Things are changing though and you will see a lot more of these standalone networks later this year and even early next year. 

The slides of the webinar are available here and the video is embedded below:

Here are some of my thoughts on why 5G SA is taking much longer than most people anticipated:

• 5G SA will force operators to move to 5G core which is a completely new architecture. The transition to this is taking much longer than expected, especially if there are a lot of legacy services that needs to be supported.
• Many operators are moving towards converged core with 4G & 5G support to simply the core. This transition is taking long.
• For taking complete advantage of 5G architecture, cloud native implementation is required. Some operators have already started the transition to cloud native but others are lagging.
• 5G SA speeds will be lower than NSA speeds hence some operators who don't have a lot of mid-band spectrum are delaying their 5G SA rollouts.
• Many operators have managed to reduce their latency as they start to move to edge datacentres, hence the urgency for 5G standalone has reduced.
• Most operators do not see any new revenue opportunities because of 5G SA, hence they want to be completely ready before rolling out 5G SA
• Finally, you may hear a lot about not enough devices supporting 5G SA but that's not the device manufacturers views.  See this tweet from GSA 👇

#Supporting5Gstandalone

With 5G SA networks now being launched, GSA is already aware of 842 announced devices with claimed support for 5G SA, up 202% from 278 at the end of 2020.

Full report on: https://t.co/8f1fw4R2fI#5G | #SA | #Devices | #GSA pic.twitter.com/7LEoyasplm

— GSA (@gsacom) July 11, 2022

Do you agree with my reasoning? If not, please let me know in the comments.

Related Posts: 

• The 3G4G Blog: The Status of 5G Standalone (5G SA) Networks - March 2021
• The 3G4G Blog: What will 5G Standalone deliver?
• The 3G4G Blog: The Politics of Standalone vs Non-Standalone 5G & 4G Speeds
• The 3G4G Blog: 5G Reality Check - Data Rates
• Operator Watch Blog: Germany gets Two 5G Standalone Networks
• The 3G4G Blog: Minimum Bandwidth Requirement for 5G Non-Standalone (NSA) Deployment
• The 3G4G Blog: 5G Dual Connectivity, Webinar and Architecture Overview
• The 3G4G Blog: What about 5G Network Architecture Option 4 (a.k.a. NE-DC) ?
• Free 5G Training: 5G Use Cases
• Free 5G Training: 5G Adverts
• 3G4G: 5G for Absolute Beginners 

Demystifying and Defining the Metaverse

There is no shortage of Metaverse papers and articles as it is the latest trend in the long list of technologies promising to change the world. Couple of months back I wrote a post about it in the 6G blog here.

TOMORROW: Hear from leading experts in the field about key questions such as how this technology is evolving, how can it be leveraged to augment business and personal environments, and what socio-technical and ethical questions have to be addressed. https://t.co/NggnJPu4eU pic.twitter.com/kfmYiCdomP

— IEEE Standards Assoc (@IEEESA) July 5, 2022

IEEE hosted a Metaverse Congress with the Kickoff Session 'Demystifying and Defining the Metaverse' this month as can be seen in the Tweet above. The video embedded below covers the following talks:

• 0:01:24 - Opening Remarks by Eva Kaili (Vice President, European Parliament)
• 0:09:51 - Keynote - Metaverse Landscape and Outlook by Yu Yuan (President-Elect, IEEE Standards Association)
• 0:29:30 - Keynote - Through the Store Window by Thomas Furness (“Grandfather of Virtual Reality”)
• 0:52:30 - Keynote - XR: The origin of the Metaverse as Water-Human-Computer Interaction (WaterHCI) by Steve Mann (“Father of Wearable Computing”)
• 1:22:17 - Keynote - A Vision of the Metaverse: AI Infused, Physically Accurate Virtual Worlds by Rev Lebaredian (VP of Omniverse & Simulation Technology, NVIDIA)

Some fantastic definitions, explanations, use cases and vision on Metaverse. The final speaker nicely summarised Metaverse as shown in this slide below.

Worth highlighting point 6 that the Metaverse is device independent. I argued about something similar when we try and link everything to 6G (like we linked everything to 5G before). We are just in the beginning phase, a lot of updates and clarifications will come in the next few years before Metaverse starts taking a final shape.

Related Posts: 

• Free 6G Training: What is Metaverse and will it play a big part in 6G?
• The 3G4G Blog: 5G eXtended Reality (5G-XR) in 5G System (5GS)
• The 3G4G Blog: A look at 5G Applications, Application Functions & Application Servers
• Free 6G Training: What is Extended Reality (XR)?
• Free 6G Training: Three Degrees of Freedom (3DoF) vs Six (6DoF) in Extended Reality
• Free 6G Training: One XR Device to Rule Them All!
• Free 6G Training: The 6G devices of 2030 

APT 600 MHz Band Gets Approval from 3GPP

The current 600 MHz 5G band (n71) is getting an extension as 3GPP approves plan for APT 600 MHz band. Back in April, the 29th meeting of the APT Wireless Group (AWG-29) organized by the Asia Pacific Telecommunity (APT) concluded with the final approval of the new APT 600 MHz band plan that hoped to open an additional 40+40 MHz prime UHF spectrum. A similar approach back in 2013 resulted in the 45+45 MHz in the 700 MHz band, known in 3GPP as n28.

3GPP TSG RAN 96 (all docs here) approved a new work item to standardize the APT 600 MHz band plan which was initially proposed by the ITU-APT Foundation of India (IAFI).

RP-221778 (revision of RP-221062), provides a detailed justification for this new band. Quoting from the document:

The 470-694 MHz frequency range is allocated to the broadcasting service and mobile service on a co-primary basis in ITU Region 3. The frequency band 470-698 MHz, or parts thereof, was identified by WRC-15 in 7 countries in Region 3 through new footnote No. 5.296A for use by those administrations as listed wishing to implement terrestrial IMT systems. In addition, there is interest from other significant markets to do the same. Elsewhere, USA, Mexico and several other countries in ITU Region 2 also identified this band for IMT through footnotes 5.295 and 5.308A. It is noted that resolves 2 of revised Resolution 224 (Rev.WRC-19) to encourage administrations to take into account results of the existing relevant ITU Radio communication Sector studies, when implementing IMT applications/systems in the frequency bands 694-862 MHz in Region 1, in the frequency band 470-806 MHz in Region 2, in the frequency band 790-862 MHz in Region 3, in the frequency band 470-698 MHz, or portions thereof, for those administrations mentioned in No. 5.296A, and in the frequency band 698 790 MHz, or portions thereof, for those administrations mentioned in No. 5.313A.

Spectrum below 1 GHz is expectedly well suited for mobile broadband applications.  In particular, the unique propagation characteristics of the bands below 1 GHz allow for wider area coverage, which in turn requires fewer infrastructures and facilitates service delivery to rural or sparsely populated areas. In this regard, the 700MHz ecosystem is growing swiftly: there are over 34 commercial networks deployments.  The APT700 band plan coming out from Region 3 played a huge role in its success globally. Outside of APAC, countries in Region 2 have adopted or plan to adopt the APT700 band plan (3GPP band 28) for LTE system deployments. The lower duplexer of APT700 plan has also been adopted for Region 1 since the conclusion of WRC-15.

As the utilisation of the 700MHz spectrum increases over time, it is desirable to look at additional spectrum that could be considered as a companion besides 3GPP Band 28. Therefore, the use of parts of the 600MHz band for the mobile broadband service would provide a vital means of delivering high quality, wide area broadband services including in rural areas and deep inside buildings. The timely availability of frequency arrangements is essential for the development of IMT specifications and standards and the early consideration by Administrations in the footnotes referred to above of suitable frequency arrangements. 

The APT region is very diverse and consists of highly developed and developing countries and some with extremely large and rural population base. The sub 1 GHz bands is well suited for the later.

During the last year or so, 3GPP RAN 4 has completed a study item on the feasibility of various duplex filter options for use in this band. The results of this study are documented in TR 38.860. This study was sent to the AWG in an LS RP-212629 in Sep 2021 with a request to provide guidance on a preferred band plan and information on regulatory aspects for the normative work to begin. The AWG 28 meeting has considered the request of the 3GPP and has provided a response to this LS. In this response the LS has indicated a preference for option B1 (full band) and has also requested for the work to begin immediately with a view to completion by Dec 2022. Additionally, the answers to the regulatory questions sought by the 3GPP have now been provided via a reply LS RP 221045.

The band plan for the option B1 that has a single duplexer or full band- is shown in Table 1 below.

The Tx-Rx is "reverse-duplex"; in other words, the downlink frequency band is below the duplex gap while the uplink frequency band is above the duplex gap. This arrangement is opposite to conventional notation; however, for this band, it provides the benefit of aligning the uplink band adjacent to 3GPP band 28 thereby minimizing interference conditions at the 703 MHz boundary.

Accordingly, the companies listed here request 3GPP to start normative work on the following option. 

• Option B1 with a single duplexer 

For anyone interested in studying this further might want to refer to 3GPP TR 38.860: Study on Extended 600 MHz NR band.

Related Posts: 

• The 3G4G Blog: LTE Band 13 mystery
• The 3G4G Blog - Radio Design Webinar: Optimising Your 700 MHz Deployments
• The 3G4G Blog: Minimum Bandwidth Requirement for 5G Non-Standalone (NSA) Deployment
• Operator Watch Blog: USA has an interesting mix of different types of 5G
• 3G4G: 50 Questions on Spectrum 

5G and Cyber Security

Dr. Seppo Virtanen is an Associate Professor in Cyber Security Engineering and Vice Head of Department of Computing, the University of Turku, Finland. At 5G Hack The Mall 2022, he presented a talk on Cybersecurity and 5G. 

In the talk he covered the following topics:

• Cybersecurity and Information Security
• The CIA (Confidentiality, Integrity and Availability) Model
• Achieving the goals of the CIA model
• Intrusion and Detection
• Intrusion detection, mitigation and aftercare
• Smart Environments
• Abstraction levels
• Cybersecurity in smart environments
• Cyber security concerns in smart environments
• Security concerns in Smart Personal Spaces
• Security concerns in Smart Rooms and Buildings
• Security concerns of a participant in a smart environment
• Cyber Security Concerns in Smart Environments
• Cyber Security in the 5G context
• Drivers for 5G security
• Securing 5G

This video embedded below is a nice introduction to cybersecurity and how it overlaps with 5G:

Related Posts:

• The 3G4G Blog: Lawful Intelligence and Interception in 5G World with Data and OTT Apps
• The 3G4G Blog: Realizing Zero Trust Architecture for 5G Networks
• The 3G4G Blog: Bug hunting in 5G Networks and Devices
• The 3G4G Blog: AT&T Cybersecurity Experts Provide 5G Security Overview
• The 3G4G Blog: Everything you need to know about 5G Security
• The 3G4G Blog: Key Technology Aspects of 5G Security by Rohde & Schwarz
• The 3G4G Blog: 5G Roaming with SEPP (Security Edge Protection Proxy)
• 3G4G: Security in 2G, 3G, 4G & 5G Mobile Networks 

3GPP Explains TSG CT Work on UAS Connectivity, Identification and Tracking

Drones, technically Unmanned Aerial Vehicles/Systems or UAVs/UASs, have been a subject of interest for a very long time due to the wide variety of use cases they can offer. In the recent issue of 3GPP Highlights newsletter, Lena Chaponniere, 3GPP Working Group CT1 Vice-Chair has written an article about TSG CT work on UAS Connectivity, Identification and Tracking. Interestingly, the 3GPP abbreviation for UAS is slightly different, Uncrewed Aerial Systems.

Quoting from the newsletter: 

One of the defining drivers of 5G is the expansion beyond traditional mobile broadband to provide solutions meeting the needs of vertical industries.

A very good example of 3GPP rising up to this challenge is the work done in Release 17 to use cellular connectivity to support Uncrewed Aerial Systems (UAS), thereby enabling this vertical to benefit from the ubiquitous coverage, high reliability, QoS, robust security, and seamless mobility provided by the 3GPP system.

A key component of this work took place in CT Working Groups, which under the leadership of Sunghoon Kim (CT Work Item rapporteur) and Waqar Zia (rapporteur of new specifications TS 29.255 and TS 29.256) developed the necessary protocols and APIs to meet the service requirements specified in 3GPP SA1 and the architectural enhancements specified in 3GPP SA2, as part of the Release 17 Work Item on ‘ID_UAS’.

The key functions of the 3GPP architecture for ID_UAS are depicted in the following figure:

The work in CT Working Groups focused on specifying support for the following features:

UAV remote identification: The CAA (Civil Aviation Administration)-Level UAV ID was introduced in the 3GPP system. It is a globally unique, electronically and physically readable, and tamper resistant identification which allows the receiving entity to address the correct USS for retrieval of UAV information and can be assigned solely by the USS, via means outside the scope of 3GPP, or assigned by the USS with assistance from 3GPP system, whereby the USS delegates the role of “resolver” of the CAA-Level UAV ID to the UAS NF.

AV USS authentication and authorization (UUAA): The first step for the owner of the UAV is to register the UAV with the USS, via a procedure outside the scope of 3GPP, which can take place offline or using internet connectivity. During this procedure, the CAA-level UAV ID is configured in the UAV and the aviationlevel information (e.g. UAV serial number, pilot information, UAS operator, etc.) is provided to the USS.

The UE at the UAV then registers with the 3GPP system by using existing procedures for 3GPP primary authentication, with the MNO credentials stored in the USIM.

After successful authentication of the UE, the UUAA procedure is performed, to enable the 3GPP Core Network to verify that the UAV has successfully registered with the USS. In 5GS, this procedure can take place during the 3GPP registration, or during the establishment of a PDU session for UAS services.

For the former, CT1 extended the registration procedure in TS 24.501 to enable the UE to indicate its CAA-Level UAV ID into a new container (Service-level-AA container) included in the Registration Request message, which triggers the AMF to initiate UUAA with the USS by invoking the Nnef_Authentication service toward the UAS NF, as specified by CT4 in new specification TS 29.256, and the UAS NF to invoke the Naf_Authentication service toward the USS, as specified by CT3 in new specification TS 29.255.

For the latter, CT1 extended the PDU session establishment procedure in TS 24.501 to enable the UE to indicate its CAA-Level UAV ID via the Service-level-AA container included in the PDU Session Establishment Request message, which triggers the SMF to initiate UUAA with the USS via the UAS NF by invoking the services mentioned above. In order to enable exchanging the authentication messages between the UE and the USS, CT1 specified a new Session Management procedure in TS 24.501, in which the SMF sends a Service-level Authentication Command to the UE in a Downlink NAS Transport message. The UE replies to this command with a Service-level Authentication Complete carried in an Uplink NAS Transport message. In EPS, the UUAA procedure takes place during PDN connection establishment, and the information exchanged to that end between the UAV and the PGW is carried in the Service-level-AA container included in the ePCO

C2 communication over cellular connectivity: C2 communication over cellular connectivity consists of the UAV establishing a user plane connection to receive C2 messages from a UAVC, or to report telemetry data to a UAVC. Authorization for C2 communication by the USS is required and includes authorization for pairing of the UAV with a UAVC, as well as flight authorization for the UAV.

C2 communication authorization may be performed:

• during the UUAA procedure (if UUAA is carried out at PDU session/PDN connection establishment) when the UAV requests establishment of a PDU Session/PDN connection for both UAS services and C2 communication
• during PDU session modification/UE requested bearer resource modification when the UAV requests to use an existing PDU session/PDN connection for C2 communication
• during a new PDU session/PDN connection establishment, if the UAV requests to use a separate PDU Session/PDN connection for C2 communication

To support this, CT1 extended the PDU session establishment and modification procedures in TS 24.501 to enable inclusion of the CAA-level UAV ID and an application layer payload containing information for UAVC pairing and for UAV flight authorization in the Service-level-AA container carried in the PDU Session Establishment Request and PDU Session Modification Request messages. The ePCO Information Element in TS 24.008 was also extended to enable it to include the above-mentioned information.

UAV location reporting and tracking: UAV location reporting and tracking was specified by CT3 and CT4 by re-using the existing Nnef_EventExposure service specified in TS 29.522 with the UAS NF acting as NEF/SCEF and interacting with other network functions (e.g. GMLC and AMF/MME) to support UAV tracking. The following tracking modes were specified:

• UAV location reporting mode: the USS subscribes to the UAS NF UAV to be notified of the location of the UAV, and can indicate the required location accuracy and whether the request is for immediate reporting or deferred reporting (e.g. periodic reporting)
• UAV presence monitoring mode: the USS subscribes for the event report of UAV moving in or out of a given geographic area
• List of Aerial UEs in a geographic area: the USS requests the UAS NF for reporting a list of the UAVs in given geographic area and served by the PLMN.

The PDF of newsletter is available here.

Related Posts: 

• Connectivity Technology Blog: Ericsson Explains Internet of Drones and 3GPP UAV Roadmap
• The 3G4G Blog: ATIS Webinar on '5G Standards Development Update in 3GPP Release 17 and 18'
• The 3G4G Blog: 3GPP Release-17 5G NR Reaches Completion
• Connectivity Technology Blog: GSMA's DIG discusses how 5G Networks will handle UAV Layer
• Connectivity Technology Blog: Vodafone and Deutsche Telekom Briefly Starts Drone War
• The 3G4G Blog: 3GPP's 5G-Advanced Workshop Summary
• Connectivity Technology Blog: 5G Drone Cell Towers
• Connectivity Technology Blog: GSMA IoT WebTalk 'Clear Skies Ahead for Mobile-Enabled Drones'
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What is a Multi-Band Cell?

Multi-band cells became very popular in modern RAN environment and beside many benefits they also come with some challenges for performance measurement and radio network optimization.

A multi-band cell consists of a default band that shall be used by UEs for initial cell selection and a set of additional frequency band carriers that typically become involved as soon as a dedicated radio bearer (DRB) for payload transmission is established in the radio connection.

The exact configuration of a multi-band cell including all available frequency bands is broadcasted in SIB 1 as shown in the example below.

Different from legacy RAN deployments where – to take the example of a LTE cell – a pair of PCI/eARFCN (Physical Cell Identity/eUTRAN Absolute Radio Frequency Number) always matches a particular ECGI (eUTRAN Cell Global Identity) the multi-band cell has many different PCI/eARFCN combinations belonging to a single ECGI as you can see in the next figure.

Now performance measurement (PM) counters for e.g. call drops are typically counted on the cell ID (ECGI) and thus, in case of mulit-band cells do not reveal on which frequency a radio link failure occurred.

However, knowing the frequency is essential to optimize the radio network and minimize connectivity problems. More detailed information must be collected to find out which of the different frequency bands performs well and which need improvement.

This becomes even more interesting if multi-band cells are used in MORAN RAN sharing scenarios.

In my next blog post I will have a closer look at this special deployment.

Related Posts:

• The 3G4G Blog: How Multiband-Cells are used for MORAN RAN Sharing