A Look into 5G Virtual/Open RAN - Part 2

In the first blog post of this series the different virtual RAN functions, interfaces and protocols have been discussed. Now it is time to have a look at a set of procedures that are required for the establishment of an UE connection in virtual 5G RAN.

The Big Picture

In 5G standalone RAN the crucial elements for user plane payload transport of an UE connection are  GTP/IP transport tunnels and a dedicated radio bearer on the radio interface.

When looking at the 5G RAN there are two of such tunnels: one on NG-U (aka N3) that is controlled by NGAP, and one on F1-U that is controlled by F1AP - see figure 1.

On behalf  of these two tunnels payload data can be transported between the 5G core network User Plane Function (UPF) to the gNB Distributed Unit (gNB-DU) and vice versa. For the transport over the 5G RAN fronthaul (realized e.g. as eCPRI) and across the radio interface a dedicated radio bearer (DRB) for the user plane transport must be configured by the gNB Central Unit for the Control Plane (gNB-CU CP).

As in LTE it is the RRC protocol that establishes this DRB. However, due to the virtualization the different protocol layers for the air interface are also distributed and the gNB-DU is in charge of all the lower layer PHY/RLC/MAC parameters (e.g the c-RNTI), while the gNB-CU CP assigns higher layer parameters of PDCP and RRC like the DRB-ID. Since only the gNB-CU CP can send downlink RRC messages to the UE the lower layer parameters from the DU first need to be sent in uplink direction to the gNB-CU CP.

Beside this parameter exchange the F1AP is also responsible for the tunnel management of the F1-U Tunnel.

The downlink tunnel endpoint information is provided by the gNB-DU using F1AP, but the uplink tunnel endpoint terminates at the gNB-CU UP and thus, its endpoint parameters are received by the gNB-CU CP when it exchanges information with the gNB-CU UP on behalf of the E1AP protocol.

Figure 1: Network Functions, Protocols and Parameters involved in Setup of User Plane Data Transmission Resources
(click on the image to see full size)

A similar situation we see for the NG-U tunnel that is controlled by NGAP, the protocol for communication between gNB-CU CP and the Access and Mobility Management Function (AMF) in the 5G core. Neither the gNB-CU CP nor hte AMF have direct access to the NG-U tunnel endpoints. Hence, E1AP is used again to transmit the downlink tunnel parameters to the gNB-CU CP while the uplink tunnel endpoint parameters must be sent by the UPF to the Session Management Function (SMF) using the Packet Forwarding Control Protocol (PFCP) and later by the SMF to the AMF over the service-based interface where the tunnel endpoint parameters are embedded in a JavaScript Object Notation (JSON) container.

By the way, JSON is a quite generic format for exchanging and storing different kind of data. Between the AMF and the SMF JSON is used to transport Non-Access Stratum Session Management messages (defined in 3GPP 24.501).

The Ladder Diagram

Having the Big Picture in mind it is now easier to look at the ladder diagram with the individual RAN messages for UE connection setup - shown in Figure 2.

It looks complicated, because the F1AP messages carry RRC plus NAS messages in uplink and downlink direction, but when understanding the underlying logic it is easy.

Figure 2: 5G VRAN Successful UE Connection Setup
(click on the image to see full size)

The very first step (in the figure: step 0) is the random access procedure executed on the MAC layer involving the UE and the gNB-DU.

After successful random access the UE sends the NR RRC Setup Request message. This is the Initial UL RRC Message transported by the F1AP from the gNB-DU to the gNB-CU CP. Actually the F1AP carries PDCP transport blocks and inside the PDCP the NR RRC messages are found, but to keep it simple I do not show the PDCP header in the ladder diagram.

Beside RRC Setup Request there are also some other initial NR RRC messages and RRC response messages possible (see step 1 and 2).

More RRC messages are transported over F1AP until the RRC Connection establishment is complete.

The NR RRC Setup Complete message also transports the initial NAS message and the reception of this message by the gNB-CU CP triggers the setup of a F1AP UE context. The concept of UE context management in F1AP is the same as in NGAP or - when looking back into the E-UTRAN - in S1AP.

The GTP/IP transport tunnel on F1-U is established during F1AP UE Context Setup assisted by E1AP Bearer Context Setup procedure that provides the necessary tunnel endpoint parameters.

In the same manner the NG-U tunnel is established by the NGAP Initial UE Context Setup procedure.

Additional NAS messages (especially for session management) and NR RRC Reconfiguration are exchanged to establish the end-to-end UE connection through the core network. And that's it.

Related Posts:

• A Look into 5G Virtual/Open RAN - Part 3: Connection Release and Suspend
• 3G4G: Open RAN, OpenRAN and O-RAN

Mobile Voice Communications is neither Dying, nor Dead!

If you have been following the mobile industry for a long time, you could be forgiven for thinking that voice communications is dead. This 2013 article for example talks about the impending death of voice and this 2018 article talks about how smartphones have killed the art of conversation. These are just examples and I have read many similar articles in the last 5-10 years.

The thing is that a lot of unnecessary calls became SMS and messages once the price of SMS and data went down. Similarly, voice ceased to be a differentiator in many markets so they started offering unlimited voice and/or SMS locally. This does not necessarily solve my requirements for international calling so I moved on to Viber, WeChat and WhatsApp.

The annual TeleGeography Report and Database update (just released) estimates that international over-the-top (OTT) voice traffic reached 1 trillion minutes in 2019, compared to just 432 billion minutes of international carrier traffic.

Anyway, with the lockdown in many countries because of coronavirus COVID-19, people have re-discovered the use of voice communications again. While I prefer having meetings on the internet, sometimes it's just simpler to call using your phone. A friend discovered that while she has some 40 GB data allowance that was generally more than enough, working from home means that she is having to use her device as a hotspot that is using up all her data. Switching from OTT calling to unlimited voice calling in her package means that she doesn't have to worry about voice calls eating her data package.

She is not alone. Operators all over are reporting the rise in voice communications:

• 27 Mar 2020 - O2 UK reported, "Since March 16th we have seen approximately 57% more voice traffic at the busiest point of the day. Typically voice traffic increases 5% year on year, and in a week we have experienced an increase of voice traffic comparable to nine years of regular demand." (link)
• 26 Mar 2020 - Official numbers reported by CTIA from Verizon, AT&T, T-Mobile, Sprint and U.S. Cellular stated that mobile voice traffic was up 24.3% while mobile data traffic was up 9.2% (see photo above - link)
• 24 Mar 2020 - Telenor Norwar tweeted, "Traffic has increased sharply since the coronary smith was seriously registered in this country. 50% increase in mobile voice, 25% increase in mobile data and 30-40% increase in fixed broadband"
• 24 Mar 2020 - T-Mobile USA released some interesting stats including gaming, etc. With regards to voice, their announcement said, "People are talking and texting more. Messaging is up dramatically, with a 26% increase in SMS (texting) and a 77% increase in MMS (pictures, multi-party texts, etc.). And, the amount of time people spend on calls has increased 17% nationwide." (link)
• 20 Mar 2020 - Telia in Denmark reported, "Thursday, March 12, the volume of speech in the network thus increased by 24% compared to the day before. Over the weekend 50% more was spoken - obviously due to a need to gain status on family and friends in the new situation. In the past working week, about 60% more has been spoken on the phone than on a normal week in March." (translated from original)

Is voice important for an operator? Probably not very much in the developed markets where users pay a good amount for data packages. In developing countries, voice is still a good source of revenue. At the TIP summit last year, Malaysian telecom giant Axiata said that ""every gigabyte costs about $1.40 to manufacture...generates only 80 cents in revenue...The 2G voice business currently funds any losses". This is not a long term sustainable model for these operators.

Of the 1000 people surveyed, top 5 things people in the USA want from 5G:
• Faster data speeds
• Improved coverage – fewer dead spots
• Clearer voice quality 🤔
• better battery life
• lower cost servicehttps://t.co/aK4ym25seW

— Zahid Ghadialy (@zahidtg) March 23, 2018

Funnily I just remembered that in a survey of over 1000 people in the USA regarding what they want from 5G, the third most important thing was "clearer voice quality". If you want to understand how voice quality is measured that see this tweet below

How do you measure voice quality! pic.twitter.com/a9aNBVMa9L

— 3G4G (@3g4gUK) May 2, 2017

We may keep on seeing a boom in voice traffic as more lockdowns occur and they are even stricter. We will have to wait and see of this habit of talking sticks or it's just for this unusual situation.

Related Posts:

• The 3G4G Blog: A quick starter on 4G voice (for beginners)

Real-life 5G Use Cases for Verticals from China

GSMA have recently published a series of reports related to China. This includes the 'The Mobile Economy China' report as well as reports on ‘Impacts of mmWave 5G in China’, ‘5G use cases for verticals China 2020’ and ‘Powered by SA case studies’. They are all available here.

China currently has 1.65bn subscribers (Excluding licensed cellular IoT) which is expected to grow to 1.73bn in 2025. The report quotes 1.20bn unique mobile subscribers that is expected to grow to 1.26bn by 2025. With a population of 1.44 billion, this would be assuming everyone over 10 years has a smartphone. 2G and 3G is being phased out so only 4G and 5G will be around in 2025. This would be different for IoT.

The 5G Use Cases for Verticals China 2020 report is comprised of 15 outstanding examples of 5G-empowered applications for verticals, ranging from industrial manufacturing, transportation, electric power, healthcare, education, to content creation, and zooms into the practical scenarios, technical features, and development opportunities for the next generation technology. Every use case represents the relentless efforts of 5G pioneers who are open, cooperative, and innovative.

1. Flexible Smart Manufacturing with 5G Edge Computing (RoboTechnik, China Mobile, Ericsson)
2. 5G Smart Campus in Haier Tianjin Washing Machine Factory (China Mobile, Haier)
3. Aircraft Surface Inspection with 5G and 8K at Commercial Aircraft Corporation of China (Comac, China Unicom, Huawei)
4. Xinfengming Group’s Smart Factory Based on MEC Technology (Xinfengming, China Mobile, ZTE)
5. SANY Heavy Industry 5G and Smart Manufacturing (Sany, China Mobile, China Telecom, ZTE)
6. Xiangtan Iron & Steel's 5G Smart Plant (Xisc, China Mobile, Huawei)
7. The Tianjin 5G Smart Port (Tianjin, China Unicom, ZTE, Trunk)
8. 5G Intelligent Connected Vehicle Pilot in Wuhan (China Mobile, Huawei, et al.)
9. 5G BRT Connected Vehicle-Infrastructure Cooperative System (China Unicom, DTmobile, et al.)
10. 5G for Smart Grid (China Mobile, Huawei, et al.)
11. Migu's "Quick Gaming" Platform (China Mobile, et al.)
12. 5G Cloud VR Demonstration Zone in Honggutan, Nanchang, Jiangxi Province (Besttone, China Telecom, Huawei)
13. 5G Cloud VR Education Application Based on AI QoE (China Telecom, Nokia, et al.)
14. China MOOC Conference: 5G + Remote Virtual Simulation Experiment (China Unicom, Vive HTC, Dell Technologies, et al.)
15. 5G-empowered Hospital Network Architecture Standard (CAICT, China Mobile, China Telecom, China Unicom, Huawei, et al.)

They are all detailed in the report here.

I have written about 5G Use Cases in a blog post earlier, which also contains a video playlist of use cases from around the world. Not many from China in there at the moment but should be added as and when they are available and I discover them.


Related Posts:

• Operator Watch Blog: China Allocates Shared Spectrum for Indoor Use, CBN gets Third Spectrum for 5G Network
• The 3G4G Blog: Examples of 5G Use Cases & Applications
• The 3G4G Blog: 5G Private and Non-Public Network (NPN)
• The 3G4G Blog: 5G and Industry 4.0
• The 3G4G Blog: What is Industrial IoT (IIoT) and how is it different from IoT?
• 3G4G: M2M, MTC & IoT
• Operator Watch Blog: China's Synchronized 5G Launch

How Cellular IoT and AI Can Help to Overcome Extreme Poverty in a Climate-resilient Way

The Democratic Republic ofthe Congo (DRC) is the second largest country in Africa and it has a significant potential for agricultural development as the country has more land (235 million hectares) than Kenya, Malawi, Tanzania, and Zambia, combined, of which only 3.4% is cultivated.

Despite this, around 13 millions of Congolese live in extreme food insecurity, among them 5 millions acutely malnourished children. Current assessments show the trend is increasing.

In the southern provinces formerly known as "Katanga" the needs in maize for human consumption sum up to 700,000 tons per year, while the local production barely amounts to 120,000 tons per year. This means the provinces have to resort to importing food from neighboring countries, which represents a huge burden on the region's economy.

Another aspect of the problem is that 80% of the local production is made by women farmers, and the biggest challenge they face is the lack of daily agronomic monitoring and guidance. There is only a limited amount of agriculture experts in the region and without assistance, the farmers’ average output is at best one ton per hectare. However, field trials have proven that by using smart farming technology they can easily produce up to 6 tons per hectare year over year with the right sustainable approach and support. Artificial intelligence (AI), the Internet of Things (IoT) and big data analytics underpinned by mobile connectivity can even do more. They bring significant potential for capturing carbon, optimizing water, pesticide and fertilizer usage, and reducing soil erosion. Thus, African women can not only provide the solution to the local food gap/insecurity but also become the primary protectors of their environment.

The basic technical concept is not new. Back in 2016 Ooredoo Myanmar launched Site Pyo, a mobile agriculture information service for smallholder farmers. At its core Site Pyo is a weather forecast app that was enhanced with weather-dependent advice for ten crops, from seed selection to harvesting and storage. In addition the app displays the actual market prices for these crops. GSMA as a co-funder of the project celebrates Site Pyo as a big success, but it seems to be limited to Myanmar. Why?

„A lot of customization needs to be done to adapt the application functionality for a particular region“, says Dieu-Donné Okalas Ossami, CEO of „e-tumba“, a French Start-up specialized in smart farming solutions for Sub-Sahara Africa. His company partners with iTK, a spin-off from CIRAD, the French Institute for tropical agronomy. The iTK crop-specific predictive models are based on years of agronomic data, but have originally been designed for big farmers. To meet the demands of women in Katanga requires more granular data for both, input and output.

As in case of Site Pyo weather predictions are important, but in addition there are data feeds from sensors on the spot. Weather stations measure constantly temperature and rainfall while sensors in the soil report its saturation with water, nitrogen and potassium.

„A typical real-time advice that our software provides is to delay the harvest for some additional days to maximize the yield“, explains Okalas Ossami. „However, even for two neighboring fields the particular advices are often different.“ 

Also the communication channels need to be taylored. Many women farmers are illiterate. For them the advice must be translated into the local language they speak and transmitted to their phones as a voice message. Those who can read and write will receive the notifications through short message service.

The mobile connectivity that links all elements of the system is realized by the mobile network operators present in the region.

Infographic: The Technical Environment Behind the Project

„Actually NB-IoT would fit to our use case“, says Okalas Ossami, „but it is not available. And there is neither LoRa nor SigFox.“ Hence, the sensors are using data connections of 3G and 4G radio access technology. In case of network outage or missing coverage a local field technician must collect the sensor data manually and transfer it to the data center through alternative channels.

It is the same field technician who installs the sensors. The woman farmers receive a basic training to understand how the system works, but they do not need to care about technical components - except keeping their mobile phones charged.

Here comes another important aspect into the game: How can the women trust this technical environment?

In case of Site Pyo the operator Ooredoo observed a quickly increasing user community measured by the number of app downloads. However, there was no indication to which extend the Myanmar farmers really used the app. The e-tumba solution addresses this gap by partnering with the non-government organization „Anzafrika“.

Anzafrika is present in the villages where the people live. One of its major targets is to overcome the extreme poverty by developing the regional economy. A key factor for this is that the smallholder farmers do not just see the market prices for their crops, but get real access to large, stable and long-term markets where these prices are paid. Anzafrika is brokering contracts between the woman farmers and large multinational corporations committed to the Economics of Mutuality, growing human, social and natural capital. The business model behind this concept was outlined by Bruno Roche and Jay Jakub in their book „Completing Capitalism:Heal Business to Heal the World“. Instead of focusing on greenhouse gas emissions (output) they insist that climate-resilient business models must measure the input needed for manufacturing goods. As an example: For one hot cup of coffee the greenhouse gas emissions are extremely low, but 3.4 liters of water are needed (most for packaging, processing and drinking) and 12 gram of top soil will be eroded. These are (among others) the expenses paid by the planet that are not taken into account by a carbon tax.

Coffee plantations are monocultures with all the known disadvantages resulting form this kind of farming. In the past the Congolese women farmers have grown maize as a monoculture. Now, with advice from Anzafrika and e-tumba they transitioned from an „all-maize“ sustenance crop to a semi-industrial „maize-sorghum“ production. This helps to minimize the top soil erosion and thus, to remunerate the natural capital involved in the process.  

Regarding the human and social capital Anzafrika monitors how the overall situation in the villages  is improving. The focus is on progress in well-beeing, satisfaction and health not just for the women farmers, but for their entire communities.

In 2019 smart farming technology have been tested and deployed with a group of 150 women in the province of Lualaba. Now, in 2020, their number is expected to rise to 500 and after 6 years the stunning target of 100,000 participants shall be met. A look at the download numbers of Site Pyo (206,000 in the course of one year) shows that these numbers are not over-optimistic.

The partnership between Anzafrika, e-tumba and iTK is now considered as a best international practice, as indicated by Patrick Gilabert, UNIDO Representative to the European Union in Brussels. It fully aligns with the development of new comprehensive strategies for Africa that aim at creating a partnership of equals and mutual interest through agriculture, trade and investment partnerships.

UNIDO, as the UN convener for the implementation of the “Industrial Decade for Development of Africa” (IDDA 3) is always ready to join forces with innovative partners.

How LTE RRC (4G) and NR RRC (5G) Protocols are used in Parallel in EN-DC (5G NSA)

Last week I had a fruitful discussion with a fellow blogger on the web, Martin Sauter (@mobilesociety) regarding a post in which he compared features of LTE RRC (3GPP 36.331) and NR RRC (3GPP 38.331).

It was Martin's impression that the NR RRC protocol is primarily designed to be used in the 5G standalone mode. However, as I wrote in a comment to his post the NR RRC protocol is already used in EN-DC radio connections.

The reason is that the UE must be informed about Hundreds of lower layer 5G parameters (physical, MAC, RLC) that are needed for the payload transmission over 5G frequencies. Indeed, when it comes to user plane data transmission the gNB works almost independently and the UE must handle LTE and NR radio links in parallel.So it has two different radio units (even if combined into a single radio chip set). This double-functionality is also one important reason why 5G smartphones are quite expensive. It is a lot of software and know-how that sits inside these chips.

How much surplus code is really necessary to enable 5G technology becomes visible when looking at trace data using a state-of-the-art protocol test and monitoring tool.

When reading the 3GPP 36.331 (LTE RRC) standard document one might have the impression that just a few 5G parameters have been incorporated into this protocol to support EN-DC connections.

However, when looking into the details of e.g. the nr-SecondaryCellGroupConfig-r15 it turns out that some this single information element is indeed a huge block of NR information (total size: 1111 Byte)

It is an entire 5G RRC message (rRCReconfiguration) that is piggybacked by the LTE rrcConnectionReconfiguration message, because in 5G non-standalone mode this is the only way to transmit 5G signaling information to the UE. And as highlighted in the upper part of the screenshot there are a couple of NR RRC messages transported in so-called NR-RRCContainers* during the EN-DC Establishment Procedure.

And what about 5G standalone mode? For this radio access technology the 3GPP 38.331 Rel. 15 protocol is suitable as well. Hence, some parameters mentioned in the standard paper will never be seen in EN-DC. A perfect example is S-NSSAI (Single Network Slice Selection Assistance Information), because network slicing requires the connection with a 5G core network as a prerequisite. 

(click on image for larger version)

* This is not an 3GPP term, but coined by the developers of the decoding engine.

A Look into 5G Virtual/Open RAN - Part 1

Although it is understood in general that virtualization and increasing complexity are inherent characteristics of 5G networks many people are surprised when they realize the significant differences of 5G RAN architecture and signaling procedures compared to what they know from LTE or UTRAN.

In this blog post series I want to highlight some details that are not immediately visible when reading the 3GPP specs.

Figure 1 shows a virtualized gNB and the protocols it uses to communicate with its internal entities as well as with the UE and peer entities in neighbor network elements/functions.

Figure 1: Virtual Network Functions and Protocols in 5G RAN
(click on the image to see full size)

The core of the whole thing is the gNB-Central Unit for the Control Plane (gNB-CU CP). This function communicates directly with the UE using the NR RRC protocol. It also "talks" to the 5G Core Network represented by the AMF using the NGAP, a protocol very similar to the S1AP known from E-UTRAN. Neighboring 5G base stations are contacted using the XnAP, neighboring eNBs can be reached by using X2AP.

The other virtual functions of the gNB are the Central Units for User Plane (gNB-CU UP) and the Distributed Units (gNB-DU). While the gNB-CU UP is responsible for handling the transport of payload the gNB-DUs deal with all the allocation of radio resources, especially the scheduling. As a result the lower layer radio interface protocols, especially RLC and MAC terminate in the gNB-DUs.

For the RAN monitoring tools and the 3GPP Minimization of Drive Test (MDT) feature this means that RRC and Logged Measurement Reports sent by UEs will be available at gN-CU CP while all uplink radio quality measurements and call-related user plane metrics is only available at the gNB-DU - see figure 3.

Figure 2: Distribution of un-correlated RAN measurement tasks among different gNB virtual functions
(click on the image to see full size) 

And today, there is no 3GPP-standardized procedure to correlate this measurement information collected by different virtual gNB functions.

The full impact of the 5G RAN virtualization becomes even more evident when looking at Figure 3. It shows a single gNB-CU CP in charge of controlling several gNB-CU UPs and gNB-DUs.

In a live network deployment a single gNB-CU CP will control hundreds of gNB-DUs and maybe several gNB-CU UPs. This is why it is misleading to compare the connectivity of a gNB-CU CP with that of a LTE eNB. Rather it could be compared with a UTRAN RNC controlling a similar number of 3G base stations.

Figure 3: 5G RAN Connectivity
(click on the image to see full size)

Looking back into figure 1 we see that the F1AP is used for communication between gNB-CU CP and its gNB-DUs while the E1AP is the protocol that connects the gNB-CU CP with surrounding gNB-CU UPs.

Call-related control plane procedures of F1AP and E1AP are very similar to what is known from NGAP. There is a UE context established between the gNB-CU CP and the gNB-DU. On F1-U a GTP tunnel is established for user plane transport. At the same time an E1 Bearer Context in gNB-CU CP and gNB-CU UP keeps track of the most relevant user plane transport parameters.

All in all for setting up a single subscriber connection in the virtualized 5G RAN there are significantly more signaling transactions necessary than in E-UTRAN. Figure 4 shows a practical example.

Figure 4: 5G RAN Call Trace in NETSCOUT Session Analyzer
(click on the image to see full size)

The volume and complexity of signaling information is increasing when the UE moves or is redirected to virtual functions within one gNB e.g. due to load balancing.

The next blog post of this series will dive deeper into details of such call scenarios.

Stay tuned...

Related Posts:

• The 3G4G Blog: A Look into 5G Virtual/Open RAN - Part 2
• 3G4G: Open RAN, OpenRAN and O-RAN

5G Private and Non-Public Network (NPN)

Private Networks have been around for a while and really took off after 4G was launched. This is due to the fact that the architecture was simplified due to the removal of CS core and also the advancements in silicon, storage, computation, etc. allowed creation of smaller and more efficient equipment that simplified private networks.

While private networks imply an isolated network for selected devices that are allowed to connect on to the network, Non-Public Networks are much broader in scope. Chief among them is the ability of certain devices to be capable of working on Private as well as Public Network or roaming between them.

I recently ran a workshop on 'Introduction to Private 4G & 5G Networks' with a well known Industry analyst Dean Bubley. One of the sections looked at the Network Architecture based on the 3GPP standards. This tutorial is a part of that particular section. Slides and video embedded below. There are also some interesting videos on YouTube that show how and why Private Networks are needed and some use cases. The playlist is embedded in the end.

Advanced: Private Networks & 5G Non-Public Networks from 3G4G

Playlist of Private Networks Use Cases.



Related Posts:

• The 3G4G Blog: 5G and Industry 4.0
• The 3G4G Blog: What is Industrial IoT (IIoT) and how is it different from IoT?
• 3G4G: M2M, MTC & IoT

5G and Industry 4.0

Telefónica published an infographic on 'Benefits of 5G in Industry 4.0' last week. You can download it on their website here. This reminded me that we have now completed the third video in our series of IoT.

1. The beginners guide to M2M, MTC & IoT is discussed here and video is available here.
2. Industrial IoT (IIoT) vs IoT is discussed here.
3. This blog post with with embedded video / slide looks at Industrie 4.0 (a.k.a. I4.0 or I4)

Internet of Things (IoT), Industrial IoT (IIoT) and Industry 4.0

Video in works #3G4G5G #I40 pic.twitter.com/zwavdn1dpL

— 3G4G (@3g4gUK) February 8, 2020

Slides and Video is embedded below, let us know what you think.

Beginners: Industry 4.0 & 5G from 3G4G

Related Posts and Links:

• 3G4G: Internet of Things (IoT) and Machine-2-Machine (M2M)
• The 3G4G Blog: M2M vs IoT
• The 3G4G Blog: What is Industrial IoT (IIoT) and how is it different from IoT?
• The 3G4G Blog: New 3GPP Release-17 Study Item on NR-Lite (a.k.a. NR-Light)

EPS Fallback in 5G Standalone Deployments

It can be expected that later this year some mobile network operators will launch their initial 5G standalone (5G SA) deployments.

Nevertheless there will remain areas with temporary or permanently weak 5G NR coverage. One possible reason might be that even when 5G and LTE antennas are co-located, which means: mounted at the same remote radio head, the footprint of the 5G NR cell is significantly smaller when it uses a higher frequency band than LTE - see figure 1.

Figure 1: Smaller footprint of co-located 5G NR cell with higher frequency

Especially UEs making Voice over New Radio (VoNR) calls from the 5G cell edge have a high risk of experiencing bad call quality, in worst case a call drop. To prevent this the UE is forced  during the voice call setup towards 5G core network (5GC) to switch to a LTE/EPS connection where the radio conditions are better for the voice service.

The same procedure for which the term "EPS Fallback" was coined by 3GPP also applies when the UE is served by a 5G cell that is not configured/not optimized for VoNR calls or when the UE does not have all needed VoNR capabilities.

Figure 2: Two options for EPS fallback

When looking at the RAN there are two options for executing the EPS Fallback as shown in figure 2.

In option A the 5G radio connection is released after the initial call attempt is successfully finished and with the 5G RRC Release the UE is ordered to reselect to a 4G cell where a new radio connection is started for the VoLTE call. In this case the UE context is transferred from the AMF to the MME over the N26 interface. 3GPP seems to use also the term "RAT fallback" for this option.

Option B is to perform a 5G-4G inter-RAT handover. Here the session management and user plane tunnels in the core network are handed over from SMF/UPF to MME/S-GW in addition. This is realized with the GTPv2 Forward Relocation procedure on N26 interface.

All in all the EPS fallback is expected to cause an additional call setup delay of approximately 2 seconds.

For the inter-RAT handover case it is easy to detect from signaling information that an EPS fallback was triggered. In the source-eNodeB-to-target-eNodeB-transparent-container sent by the gNB to the eNB a boolean "IMS voice EPS fallback from 5G" indicator will be found that is set to "true". This container is named according to the receiving entity and will be carried by the NGAP Handover Preparation, GTPv2 Forward Relocation Request and the S1AP Handover Request messages.

If a redirection for Voice EPS Fallback is possible or not is indicated in the NGAP Initial Context Setup Request, Handover Request (during 5G intra-system handover) and Path Switch Request Acknowledge (after Xn handover) messages, all sent by the AMF to the gNB.

Further the NGAP protocol provides the cause value "IMS voice EPS fallback or RAT fallback triggered" in the PDU Session Resource Modify Response message indicating that a requested VoNR session cannot be established.  

An excellent, very detailed description of N26 interface functionality and testing ia available here.

AI your Slice to 5G Perfection

Back in November, The Enhanced Mobile Broadband Group in CW (Cambridge Wireless) held an event on 'Is automation essential in 5G?'. There were some thought provoking presentations and discussions but the one that stood out for me was by Dan Warren from Samsung

I consider that to be quite an achievement. I'll take it as a compliment #cwembb

— Dr. Dan Warren (@TMGB) November 28, 2019

The slides are embedded below but I want to highlight these points:

• Some Network Functions will be per slice whereas others will be multi-slice, the split may not be the same for every slice
• Two slices that have the same 'per slice vs multi-slice' functional split may be different network hardware topologies
• Enterprise customers will likely want a 'service' contract that has to be manifested as multiple slices of different types. 
• Physical infrastructure is common to all slices

The last point is very important as people forget that there is a physical infrastructure that will generally be common across all slices.

Again, when you apply Artificial Intelligence (AI) to optimize the network functions, does it do it individually first and then end-to-end and if this is applied across all slices, each of which may have a different functionality, requirement, etc. How would it work in practice?

Agree with pretty much all of this, but there are other points. Key to success of this as a 'full industry' solution is how slicing works when roaming and across interconnect. That is fundamental to SLA support on fully mobile devices and applications (inc. NPN to MNO mobility)

— Dr. Dan Warren (@TMGB) February 4, 2020

5G - Peak Complexity from 3G4G

As Dan says in his tweet, "It is hard to implement AI to optimise a point solution without potentially degrading the things around it.  Constantly being pushed to a bigger picture view => more data => more complexity"

Let me know what you think.

Related Posts:

• Tutorial: Service Based Architecture (SBA) for 5G Core (5GC)
• Exploring Network Convergence of Mobile, Broadband and Wi-Fi
• Prof. Andy Sutton: Backhauling the 5G Experience - Jan 2020
• 5G Core Architecture Webinar from Apis
• 5G and Fixed-Mobile Convergence (FMC)
• Updated 5G Terminology Presentation