Monday, 18 July 2022

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.

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Tuesday, 5 July 2022

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:

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Tuesday, 28 June 2022

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.

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Thursday, 16 June 2022

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.

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Monday, 13 June 2022

Tutorial on 4G/5G Mobile Network Uplink Working and Challenges

People involved with mobile technology know the challenges with uplink for any generation of mobile network. With increasing data rates in 4G and 5G, the issue has become important as most of the speeds are focused on download but upload speeds are quite poor.

People who follow us across our channels know of many of the presentations we share across them from various sources, not just ours. One such presentation by Peter Schmidt looked at the uplink in details. In fact we recommend following him on Twitter if you are interested in technical details and infrastructure.

The details of his talk as follows:

The lecture highlights the influences on the mysterious part of mobile communications - sources of interference in the uplink and their impact on mobile communication as well as practices for detecting sources of RF interference.

The field strength bar graph of a smartphone (the downlink reception field strength) is only half of the truth when assessing a mobile network coverage. The other half is the uplink, which is largely invisible but highly sensitive to interference, the direction from the end device to the base stations. In this lecture, sources of uplink interference, their effects and measurement and analysis options will be explained.

Cellular network uplink is essential for mobile communication, but nobody can really see it. The uplink can be disrupted by jammers, repeaters, and many other RF sources. When it is jammed, mobile communication is limited. I will show what types of interference sources can disrupt the uplink and what impact this has on cellular usage and how interference hunting can be done.

First I explain the necessary level symmetry of the downlink (from the mobile radio base station - eNodeB to the end device) and the uplink (from the end device back to the eNodeB). Since the transmission power of the end device and eNodeB are very different, I explain the technical background to achieving symmetry. In the following I will explain the problems and possibilities when measuring uplink signals on the eNodeB, it is difficult to look inside the receiver. In comparison, the downlink is very easy to measure, you can see the bars on your smartphone or you can use apps that provide detailed field strength information etc. However, the uplink remains largely invisible. However, if this is disturbed on the eNodeB, the field strength bars on the end device say nothing. I will present a way of observing which some end devices bring on board or can be read out of the chipset with APPs. The form in which the uplink can be disrupted, the effects on communication and the search for uplink sources of disruption will complete the presentation. I will also address the problem of 'passive intermodulation' (PIM), a (not) new source of interference in base station antenna systems, its assessment, measurement and avoidance.

The slides are available here. The original lecture was in German, a dubbed video is embedded below:

If you know of some other fantastic resources that we can share with our audience, please feel free to add them in the comments.

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Monday, 6 June 2022

2G/3G Shutdown may Cost Lives as 4G/5G Voice Roaming is a Mess

You have probably heard me a complaining about the pace of VoLTE rollout, 2G/3G shutdowns, 4G Voice roaming, etc. This post highlights all these issues coming together in a dangerous way. People often ask me why is it that it's always just me highlighting the issues. The answer is that there are other people but their voice may not reach you. In this post, I am highlighting presentations by Rudolf van der Berg, Project and programme manager at Stratix Consulting.

Let's start with Rudolf's post from LinkedIn:

Stop the shutdown of 2G and 3G networks to save lives. This is the urgent call I make today and I hope you can help me spread it! Please call on people you know in politics, regulators and emergency services to demand a stop! Call on anyone you know in the GSMA, 3GPP, handset makers (Apple, Samsung, Qualcomm, MediaTek), network builders (Ericsson, Nokia, Huawei) to re-engineer VoLTE to an interoperable standard.

Emergency calls (112, 911) should work anywhere in the world on any phone. For GSM and 3G voice calling it did. You could fly anywhere and call emergency services and in the EU we have the roaming regulation that demands calling like at home. Voice over 4G and 5G hasn't been properly standardized and isn't interoperable between networks, devices, chipsets and firmware. People need to be able to make and receive telephone calls around the world, to each other and to emergency services. Unfortunately even according to sector itself emergency services are at risk from VoLTE. A consumer today can't know whether a phone they bought will make VoLTE calls at home or abroad, nor whether it can reach emergency services. That can't be right!

So please help EENA 112 and me share this message! Thank you #eena2022 (Slide 4 contains a mistake, T-Mo USA hasn't decided on 2G shutdown yet. that is good for availability of 911, though fundamental point remains. Apologies.)

The video and slides are embedded below:

The slides contain many useful references and links, you can download directly from here.

Back in April, iBASIS hosted a VoLTE and 5G Roaming Roundtable. You can watch the video here and download the presentation and whitepaper as well. It contains talks from Kaleido Intelligence, iBASIS, KPN, Bouygues Telecom and Telus. 

The slide from Dutch MNO KPN above highlights the VoLTE Roaming issues they are observing. Other operators will face this issue sooner or later as well. 

The Regulators, GSMA and 3GPP have to come together to fix this important issue for once and all so no lives are lost because of this. Hopefully someone is listening!

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Tuesday, 31 May 2022

Transitioning from Cloud-native to Edge-Native Infrastructure

We have looked at what we mean by cloud-native in an earlier post here. Recently we also looked at edge-native infrastructure here. While we have been debating between cloud and edge for a while, in a new presentation (embedded below), Gorkem Yigit, Principal Analyst, Analysys Mason argues that the new, distributed IT/OT applications will drive the shift from cloud-native to edge-native infrastrcuture.

The talk by Gorkem on '5G and edge network clouds: industry progress and the shape of the new market' from Layer123 World Congress 2021 is as follows:

A blog post by ADVA has a nice short summary of the image on the top that was also presented at a webinar earlier. The following is an extract from that blog post: 

The diagram compares hyperscale (“cloud-native infrastructure”) on the left with hyper-localized (“edge-native infrastructure”) on the right.

  • Computing: The traditional hyperscale cloud is built on centralized and pooled resources. This approach enables unlimited scalability. In contrast, compute at the edge has limited scalability, and may require additional equipment to grow applications. But the initial cost at the edge is correspondingly low, and grows linearly with demand. That compares favorably to the initial cost for a hyperscale data center, which may be tens of millions of dollars.
  • Location sensitivity and latency: Users of the hyperscale data center assume their workloads can run anywhere, and latency is not a major consideration. In contrast, hyper-localized applications are tied to a particular location. This might be due to new laws and regulations on data sovereignty that require that information doesn’t leave the premises or country. Or it could be due to latency restrictions as with 5G infrastructure. In either case, shipping data to a remote hyperscale data center is not acceptable.
  • Hardware: Modern hyperscale data centers are filled with row after row of server racks – all identical. That ensures good prices from bulk purchases, as well as minimal inventory requirements for replacements. The hyper-localized model is more complicated. Each location must be right-sized, and supply-chain considerations come into play for international deployments. There also may be a menagerie of devices to manage.
  • Connectivity: Efficient use of hyperscale data centers depends on reliable and high-bandwidth connectivity. That is not available for some applications. Or they may be required to operate when connectivity is lost. An interesting example of this case is data processing in space, where connectivity is slow and intermittent.
  • Cloud stack: Hyperscale and hyper-localized deployments can host VMs and containers. In addition, hyper-localized edge clouds can host serverless applications, which are ideal for small workloads.
  • Security: Hyperscale data centers use a traditional perimeter-based security model. Once you are in, you are in. Hyper-localized deployments can provide a zero-trust model. Each site is secured as with a hyperscale model, but each application can also be secured based on specific users and credentials.

You don’t have to choose upfront

So, which do you pick? Hyperscale or hyper-localized?

The good news is that you can use both as needed, if you make some good design choices.

  • Cloud-native: You should design for cloud-native portability. That means using technologies such as containers and a micro-services architecture.
  • Cloud provider supported edge clouds: Hyperscale cloud providers are now supporting local deployments. These tools enable users to move workloads to different sites based on the criteria discussed above. Examples include IBM Cloud Satellite, Amazon Outposts, Google Anthos, Azure Stack and Azure Arc.

You can also learn more about this topic in the Analysys Mason webinar, “From cloud-native to edge-native computing: defining the cloud platform for new use cases.”. You can also download the slides from there after registration.

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Monday, 23 May 2022

5G Reality Check - Data Rates

One of the common questions that we encounter is why are 5G speeds so low as we were promised 5G downlink speeds of 20 Gbps. Most people do not understand how the 5G speeds are calculated and what do they depend on. In many cases, the network won’t be capable of delivering higher speeds due to some or the other limitation. 

In a new presentation, I try to explain the theoretical speeds and compare them with real world 5G data rates and even try to map it to why these speeds are what they are. Hopefully people won't mind me adding some humour as I go along.

Video and Slides embedded below

Embedded below is the Twitter thread on Speedtests ðŸ˜‚

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Monday, 16 May 2022

Lawful Intelligence and Interception in 5G World with Data and OTT Apps

Not long ago we looked at the 'Impact of 5G on Lawful Interception and Law Enforcement' by SS8. David Anstiss, Senior Solutions Architect at SS8 Networks gave another interesting talk on Evolving Location and Encryption Needs of LEAs in a 5G world at Telecoms Europe Telco to Techco virtual event in March.

In this talk, David provided an insight in​to how 5G is impacting lawful interception and the challenges Law Enforcement Agencies face as they work with Communication Service Providers to gather intelligence and safeguard society. While there is an overlap with the previous talk, in this video David looked at a real world example with WhatsApp. The talk also covered:

  • Real-world problems with 5GC encryption
  • 5G location capabilities and the impact on law enforcement investigations
  • Optimal solutions for both CSPs and LEAs

The video of the talk is embedded below:

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Monday, 9 May 2022

Transitioning from eCall to NG-eCall and the Legacy Problem

eCall (an abbreviation of "emergency call") is an initiative by the European Union, intended to bring rapid assistance to motorists involved in a collision anywhere within the European Union. The aim is for all new cars to incorporate a system that automatically contacts the emergency services in the event of a serious accident, sending location and sensor information. eCall was made mandatory in all new cars sold within the European Union as of April 2018.

In UK, the National Highways have a fantastic summary of the eCall feature here. The following video explains how this feature works:

Last year, ETSI hosted the Next Generation (NG) eCall webinar and Plugtests. The presentations from the event are available here. The presentations from GSMA, Qualcomm and Iskratel have a fantastic summary of many of the issues and challenges  with eCall and transitioning to NG eCall.

From the Qualcomm presentation:

The eCall standardisation began in 2004 when 2G networks were prevalent and 3G was being deployed. The chosen solution was in-band modem and Circuit Switched (CS) 112 call. The in-band modem was optimised for GSM (2G) and UMTS (3G) as the standard completed in 2008.

eCall for 4G (NG eCall) standardisation was started in 2013 and completed in 2017. As there is no CS domain in 4G/5G, IMS emergency calling will replace circuit switched emergency call. Next generation (NG) eCall provides an extension to IMS emergency calls and support for 5G (NR) has since been added.

The picture above from GSMA presentation highlights the magnitude of the problem if NG eCall deployment is delayed. GSMA is keen for the mobile operators to switch off their 2G/3G networks and only keep 4G/5G. There are problems with this approach as many users and services may be left without connectivity. Fortunately the European operators and countries are leaving at least one previous generation of technology operational for the foreseeable future.

GSMA's presentation recommends the following:

  • New technology neutral eCall Regulation (type approval and related acts) to be amended, adopted by European Commission and enter into force by end 2022 the latest.
  • OEMs to start installing NG eCall /remotely programable/exchangeable modules by end 2022; by end 2024 all new vehicles sold in the market should be NG eCall only
  • New vehicle categories to start with NG eCall only by 2024
  • MNOs have initiated to phase out 2G/3G between 2020 and 2025 , whereas the optimal transition path of their choice beyond this date will depend on market and technology specifics, and may require alignment with NRAs.
  • By 2022 , the industry will develop solutions for the transition period that need to be implemented country by country, which will also assess the amount of needed public funding to be economically feasible.
  • Retrofitting to be acknowledged, completed and formalised as a process by end 2024; standards should already be available in 2022.
  • Aftermarket eCall solution to be completed (including testing) and formalised by end 2024; standards should already be available in 2022.
  • The European Commission to make available public funding to support OEMs and alternative solutions to legacy networks starting from 2022 , under the RRF/ recovery package (or other relevant instruments)
  • Legacy networks availability until 2030 at the latest. By then deployment of all alternative solutions simultaneously would have ensured that the remaining legacy fleet will continue to have access to emergency services through NG eCall.

EENA, the European Emergency Number Association, is a non-governmental organisation whose mission is to contribute to improving people’s safety & security. One of the sessions at the EENA 2021 Conference was on eCall. The video from that is embedded below and all information including agenda and presentations are available here.

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