Showing posts with label 4G. Show all posts
Showing posts with label 4G. Show all posts

Wednesday, 7 July 2021

Different Types of RAN Architectures - Distributed, Centralized & Cloud


I come across a question relating to the different type of RAN architectures once per month on an average. Even though we have covered the topic as part of some or the other tutorial, we decided to do a dedicated tutorial on this.

The video and slides are embedded below

As always, feedback and comments welcome.

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Wednesday, 30 June 2021

Open RAN Terminology and Players


When we made our little Open RAN explainer, couple of years back, we never imagined this day when so many people in the industry will be talking about Open RAN. I have lost track of the virtual events taking place and Open RAN whitepapers that have been made available just in the last month.

One of the whitepapers just released was from NTT Docomo, just in time for MWC 2021. You can see the link in the Tweet

Even after so much information being available, many people still have basic questions about Open RAN and O-RAN. I helped make an Open RAN explainer series and blogged about it here. Just last week, I blogged about the O-RAN explainer series that I am currently working on, here.

There were some other topics that I couldn't cover elsewhere so made some short videos on them for the 3G4G YouTube channel. The first video/presentation explains Open RAN terminology that different people, companies and organizations use. It starts with open interfaces and then looks at radio hardware disaggregation and compute disaggregation. Moving from 2G/3G/4G to 5G, it also explains the Open RAN approach to a decomposed architecture with RAN functional splits.

If you look at the Telecom Infra Project (TIP) OpenRAN group or O-RAN Alliance, the organizations driving the Open RAN vision and mission, you will notice many new small RAN players are joining one or both of them. In addition, you hear about other Open RAN consortiums that again include small innovative vendors that may not be very well known. 

The second video is an opinion piece looking at what is driving these companies to invest in Open RAN and what can they expect as return in future.

As always, all 3G4G videos' slides are available on our SlideShare channel.

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Thursday, 24 June 2021

O-RAN Introduction for Beginners


Having been writing about Open RAN for a while, I thought it was important to make simple beginners tutorials for O-RAN. As my full time job* is with a company that is heavily involved in Open RAN and O-RAN, I had an insiders view for doing this project. 

I am making a series of videos for Parallel Wireless to help the industry become familiar with the technology and terminology. The playlist is embedded below:

Four of these are ready and more will be added as and when I get some time. Here is a summary of the videos available. Some of them also have a corresponding blog that I am linking below.

  1. Introduction to O-RAN Philosophy: This explains the basics of O-RAN and how O-RAN is transforming the mobile networks industry towards open, intelligent, virtualized and fully interoperable RAN.
  2. Introduction to O-RAN Timeline and Releases: This part looks at important timelines from the O-RAN Alliance, understand the O-RAN Software Community (OSC) and the role it plays in O-RAN, and finally, looks at the O-RAN Open-Source Software releases.
  3. Introduction to O-RAN Architecture: This part looks at how the basic OpenRAN architecture is evolving into the O-RAN Alliance based Intelligent, Virtualized and Fully Interoperable RAN. It starts with a high-level ORAN architecture and then delves into details of Service Management and Orchestration (SMO), Non-Real-Time (Non-RT) RAN Intelligent Controller (RIC), Near-RT RIC and O-Cloud.
  4. O-RAN Technical Steering Committee (TSC) & Workgroups: This part looks at O-RAN Technical Steering Committee (TSC) & Workgroups (WGs). The O-RAN TSC decides or gives guidance on O-RAN technical topics and approves O-RAN specifications prior to the Board approval and publication. The TSC consists of Member representatives and the technical workgroup co-chairs, representing both Members and Contributors. Within the TSC, there are 10 work groups, 4 focus groups, Open-Source Community and Minimum Viable Plan Committee. These have all been discussed within the video.

I am hoping that I will be able to do a few more parts and add a lot more information to the basics so a handy resource is available for anyone interested. Feel free to add links, suggestions, etc. in the comments below. 

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*Full Disclosure: I work for Parallel Wireless as a Senior Director, Technology & Innovation Strategy. This blog is maintained in my personal capacity and expresses my own views, not the views of my employer or anyone else. Anyone who knows me well would know this.

Monday, 29 March 2021

5G RAN Functional Splits

I have been meaning to write a post on RAN functional splits and even make a video. Recently I came across multiple of these things so I am taking a shortcut by posting them here. 

The first is this basic introductory video from Parallel Wireless where they explain why you need RAN splits providing examples of various functional splits for 4G and 5G mobile networks. It is embedded below:

The next one is slightly detailed video from the book "5G Radio Access Network Architecture: The Dark Side of 5G" by Sasha Sirotkin (Editor). I wrote a review of the book here and Sasha kindly made a video for our channel which is embedded below:

Finally, RCR Wireless published an article looking at the 5G functional splits in detail, by Ankur Sharma, Associate Vice President, Product Management and Strategy, Radisys. The article 'Exploring functional splits in 5G RAN: Tradeoffs and use cases' is available here.

Feel free to suggest other videos, articles, etc. in comments.

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Monday, 15 February 2021

Open RAN Explanation, Videos, White papers and Other Resources


Couple of years back, just before MWC 2019, we made what I would like to think of as the first proper explanation of Open RAN. I posted it on this blog here and the video has been viewed nearly 45,000 times. At that time, the concept of Open RAN was still quite new and in my day job with Parallel Wireless*, I was spending quite some time explaining what it really means.

Anyway, I think it made the concept of Open RAN so easy to understand that I have seen tens, if not hundreds, of people copy it, but only a few kind people give credit. 

With the Telecom Infra Project (TIP) and O-RAN driving the ecosystem further, I along with my Parallel Wireless colleagues, created a series of videos to explain the concept a bit more in detail. As expected, the introductory videos have been extremely popular while the others have been reasonably popular as well. The concept from these videos have been copied even far and wider than the original one. 

Embedded below is the playlist of all the videos (6 currently but 1 more in works):

In addition to these, I maintain a list of Open RAN whitepapers (publicly available without registration), some good articles, etc. on the 3G4G website here. I try and update the site on a regular basis so feel free to put any resources in the comments of this post and I will add them on the site during the next update.

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*Full Disclosure: I work for Parallel Wireless as a Senior Director, Technology & Innovation Strategy. This blog is maintained in my personal capacity and expresses my own views, not the views of my employer or anyone else. Anyone who knows me well would know this. 

Friday, 15 January 2021

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

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

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

Release 16 RACS does not apply to NB-IoT.

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

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

The components of this new ID are:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Monday, 23 November 2020

Radio Design Webinar: Optimising Your 700 MHz Deployments

 


Radio Design, the award-winning market leader in the provision of wireless infrastructure sharing solutions and RF filter systems, hosted a webinar last week focused on the deployment of the 700 MHz frequency band. This new 700 MHz spectrum is in great demand across the world, mainly due to its long anticipated use as low band 5G spectrum. The webinar explores the potential of this band, as well as how to prepare for potential challenges when deploying.

For people who are familiar with our trainings, we divide the spectrum into three layers, the coverage layer, the capacity layer and the high-throughput layer. 700 MHz is the most popular coverage layer spectrum worldwide.

The slide above from the webinar talks of the recent Austrian 5G Spectrum auction that we blogged about. See tweet below for details

In the webinar, slides and video embedded below, Radio Design’s founder – Eric Hawthorn – kicks things off by analysing the benefits of deploying the 700 MHz band in the real world, before passing over to Global Engineering Director – Steve Shaw – who explores some of the technical problems which can arise, as well as some of the solutions. Last but not least, COO and co-owner of Keima – Iris Barcia – provides her insight into the benefits of deploying the 700 MHz band.

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Tuesday, 17 November 2020

5G Non IP Data Delivery and Lightweight M2M (LwM2M) over NIDD

Earlier this year, MediaTek had announced that its MT2625 NB-IoT chip has been validated for LwM2M over NIDD on SoftBank Corp.’s cellular network across Japan. This achievement marks the first global commercial readiness of LwM2M over NIDD; a secure, ultra-efficient IoT communications technique that is being adopted by operators worldwide. The benefits of LwM2M over NIDD include security improvements, cost-efficient scalability and reduced power consumption.

LwM2M over NIDD is a combination of the communication technology "NIDD (Non-IP Data Delivery)" that does not use an IP address in LTE communication NB-IoT for IoT and the device management protocol "LwM2M (Lightweight M2M)" advocated by the Open Mobile Alliance. It's been a while since I wrote about Open Mobile Alliance on this blog. OMA SpecWorks is the successor brand to the Open Mobile Alliance. You can read all about it here.


OMA SpecWorks’ LightweightM2M is a device management protocol designed for sensor networks and the demands of a machine-to-machine (M2M) environment. With LwM2M, OMA  SpecWorks has responded to demand in the market for a common standard for managing lightweight and low power devices on a variety of networks necessary to realize the potential of IoT. The LwM2M protocol, designed for remote management of M2M devices and related service enablement, features a modern architectural design based on REST, defines an extensible resource and data model and builds on an efficient secure data transfer standard called the Constrained Application Protocol (CoAP). LwM2M has been specified by a group of industry experts at the OMA SpecWorks Device Management Working Group and is based on protocol and security standards from the IETF.

You can get all the LwM2M resources here and the basic specs of 'Lightweight M2M 1.1: Managing Non-IP Devices in Cellular IoT Networks' here.
The 5G Americas whitepaper 'Wireless Technology Evolution Towards 5G: 3GPP Release 13 to Release 15 and Beyond' details how Current Architecture for 3GPP Systems for IOT Service Provision and Connectivity to External Application Servers. It also talks about Rel-13 Cellular IoT EPS Optimizations which provide improved support of small data transfer over control plane and user plane. Control Plane CIoT EPS Optimization transports user data (measurements, ID, status, etc.) via MME by encapsulating user data in NAS PDUs and reduces the total number of control plane messages when handling a short data transaction. Control Plane CIoT EPS optimization, designed for small infrequent data packets, can also be used for larger data bursts depending in UE Radio capability.

User data transported using the Control Plane CIoT EPS Optimization, has special characteristics, as different mobility anchor and termination nodes.

Therefore, the Preferred Network Behavior signaling must include information on:
  • Whether Control Plane CIoT EPS optimization is supported
  • Whether User Plane CIoT EPS optimization is supported
  • Whether Control Plane CIoT EPS optimization is preferred or whether User Plane CIoT EPS optimization is preferred
These optimizations have enabled:
  • Non-IP Data Delivery (NIDD) for both: mobile originated and mobile terminated communications, by using SCEF (Service Capability Exposure Function) or SGi tunneling. However, it has to be taken into account that Non-IP PDUs may be lost and its sequence is not guaranteed
  • For IP data, the UE and MME may perform header compression based on Robust Header Compression (ROHC) framework
  • NB-IoT UE can attach but not activate any PDN connection
  • High latency communication handled by the buffering of downlink data (in the Serving GW or the MME)
  • SMS transfer
  • EPS Attach, TA Update and EPS Detach procedures for NB-IoT only UEs, with SMS service request
  • Procedures for connection suspend and resume are added
  • Support for transfer of user plane data without the need for using the Service Request procedure to establish Access Stratum context in the serving eNodeB and UE
When selecting an MME for a UE that is using the NB-IoT RAT, and/or for a UE that signals support for CIoT EPS Optimizations in RRC signaling, the eNodeB’s MME selection algorithm shall select an MME taking into account its Release 13 NAS signaling protocol.

Mpirical has a nice short video explaining 5G Non IP Data Delivery. It is embedded below.

IoT has not taken off as expected and prophesised for years. While the OMASpecWorks is doing some fantastic work by defining simplified approach for IoT deployment, its current member list doesn't have enough operators to drive the uptake required for its spec adoption. They would argue that it doesn't matter how many members there are as the NIDD approach is completely optional and over-the-top. Let's wait and see how it progresses.

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Thursday, 3 September 2020

Two Types of SMS in 5G


GSMA recently published updated "5G Implementation Guidelines: SA Option 2". It explains the two types of SMS in 5G, the same way there were 2 types of SMS in LTE.

Within 5GC, SMS Function (SMSF) supports SMS over NAS (SMSoNAS) defined in 3GPP TS 23.501. Besides, SMSoIP can also be considered as IMS based SMS solution under 5G network. SMSoIP can be deployed simultaneously with voice service over IMS to provide both voice and short message service. It is recommended to use SMSoNAS solution if voice services over IMS is not supported or for a 5G data card/Machine Type Communications (MTC)/Non-IMS device without voice service. The network architecture of SMSoIP and SMSoNAS is shown in Figure.
Mpirical explains it in the video as embedded below:


You may also find "5G SMS is Very Real and Here to Stay" by William Dudley useful. It covers a lot of technical details and signalling. It's available here.

Related  posts:

Monday, 27 July 2020

Key Technology Aspects of 5G Security by Rohde & Schwarz


The 3G4G page contains a lot of useful papers and links to security here but we have also looked at evolution of security from 4G to 5G here. Rohde & Schwarz has a short 8-minute video in which wireless technology manager, Reiner Stuhlfauth, explains the key technology aspects ensuring 5G security. The video is embedded below.



Related Links:

Saturday, 4 July 2020

An Introduction to Vehicle to Everything (V2X) and Cellular V2X (C-V2X)


We made an introductory tutorial explaining vehicle to everything. There are 2 different favours of V2X as shown in this tweet below


One is based on IEEE 802.11p (802.11bd in future). It is known by different names, DSRC, ITS-G5, etc. The other is the cellular V2X or C-V2X. It started as basic D2D but has evolved over the time. The slides and video are embedded below but this topic will need revisiting with more details.







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Monday, 22 June 2020

Carrier Aggregation (CA) and Dual Connectivity (DC)


This topic keeps coming up every few months with either someone asking me for clarifications or someone asking us to make a video. While I don't think I will mange to get round to making a video sometime soon, there are some excellent resources available that should help a new starter. Here they are in an order I think works best



The first resource that I think also works best is this webinar / training from Award Solutions. It covers this topic well and the image at the top of the post is a god summary for someone who already understands the technology.


It may also help to understand that in the 5G NSA can have 4G carrier aggregation as well as 5G carrier aggregation in addition to dual connectivity.


If you saw the video earlier, you noticed that DC actually came as part of LTE in Release-12. We covered it in our Telecom Infrastructure blog here. NTT Docomo Technical journal had a detailed article on 'Carrier Aggregation Enhancement and Dual Connectivity Promising Higher Throughput and Capacity' that covered DC in a lot more technical detail, albeit from LTE point of view only. The article is available here. A WWRF whitepaper from the same era can also provide more details on LTE Small Cell Enhancement by Dual Connectivity. An archived copy of the paper is available here.

Another fantastic resource is this presentation by Rapeepat Ratasuk and Amitava Ghosh from Mobile Radio Research Lab, Nokia Bell Labs. The presentation is available here and details the MCG (Master Cell Group) Split Bearer and SCG (Secondary Cell Group) Split Bearer, etc. This article from Ericsson also provides more detail on this topic while ShareTechNote takes it one level even deeper with technical details and signalling here and here.

So hopefully this is a good detailed starting point on this topic, until we manage to make a simple video someday.

Wednesday, 6 May 2020

Virve 2.0 - Finland's 4G/5G Public Safety Network

State Security Networks Group Finland (Erillisverkot) safeguards the Finnish society by offering authorities and critical operators engaged in critical infrastructure and services secure and reliable ICT services. Much like in the civilian world, communication between authorities includes transferring images and video material to an increasing degree, which results in ever-growing data transfer volumes and, subsequently, new kinds of demands for all communication networks. 


Virve is a means of ensuring communication and cooperation between authorities and other partners across organisational borders into the future. It also entails the introduction of a higher service standard, as the transfer to broadband, estimated to take place in 2022, will make it possible to transfer video material, images and data. This will mean that it will be possible to send video material in a reliable and secure way in the case of accidents, for example. The radio network Virve, based on Tetra technology, will reach the end of its lifecycle by the end of the 2020s. The current Virve network will be used simultaneously with the new Virve 2.0 network until, at least, 2025.


Erillisverkot will acquire the broadband Virve 2.0 radio access network as a service from Elisa and the core systems from Ericsson. Separate networks will ensure the continuity of critical communications and operational capability of public safety in all situations in the future.

I would assume this would be MOCN, similar to the UK deployment of ESN networks as shown here.

Virve 2.0 subcribers will use Elisa’s public radio network, which the operator is expanding to become Finland’s largest data and voice network.

About 80 million messages pass through the Virve system every week. Elisa is committed to increasing the coverage, capacity and verification of its mobile network to meet the requirements of Virve 2.0.

The new online services will provide support for critical communication between public authorities and other parties.

The addition of image, video, and other wireless broadband services alongside existing Virve services will enable a better and more up-to-date view of the day-to-day operations of authorities and other actors.

The IoT enables automatic monitoring of rescue personnel and mobile use of surveillance cameras and drones.

The Virve 2.0 radio network service will be in use from 2021 and will include the 4G and 5G technologies and the internet of things. The contract is for ten years.

Finally, a recent advert of Elisa explaining 5G to outside world



Further Study:
  • Erillisverkot: Obstacles for MCX Broadband and how to overcome them [PDF]
  • Erillisverkot: Virve Broadband Plans for the Future - Critical Communications Europe 2019 [PDF]
  • 5G-XCast Whitepaper: Rapidly Deployable Network System for Critical Communications in Remote Locations [PDF]
  • Erillisverkot: White paper - Virve 2.0 RFI Summary of responses [PDF]
  • Erillisverkot: Factsheet - What is Virve 2.0? [PDF]

Related Posts:

Monday, 9 March 2020

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.

Friday, 21 February 2020

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.

Sunday, 26 January 2020

NTT Docomo's Vision on 5G Evolution and 6G


NTT Docomo released a whitepaper on 5G Evolution and 6G. In a press release they announced:

NTT DOCOMO has released a white paper on the topic of 6G, the sixth-generation mobile communications system that the company aims to launch on a commercial basis by 2030. It incorporates DOCOMO's views in the field of 5G evolution and 6G communications technology, areas that the company has been researching since 2018. The white paper summarizes the related technical concepts and the expected diverse use cases of evolving 5G and new 6G communication technologies, as well as the technology components and performance targets.

Mobile communication systems typically evolve into the next generation over a period of roughly ten years; DOCOMO commenced its research into the commercial launch of 5G in 2010. In 2018, the company conducted successful radio wave propagation experiments at frequencies of up to 150 GHz, levels which are expected to enable the much faster and larger-capacity communications that 6G will require.

DOCOMO will continue to enhance the ultra-high-speed, large-capacity, ultra-reliable, low-latency and massive device-connectivity capabilities of 5G technology. It will continue its research into and development of 5G evolution and 6G technology, aiming to realize technological advances including:

  • the achievement of a combination of advances in connectivity, including ultra-high speed, large capacity and low latency
  • the pioneering of new frequency bands, including terahertz frequencies
  • the expansion of communication coverage in the sky, at sea and in space
  • the provision of ultra-low-energy and ultra-low-cost communications
  • the ensuring of highly reliable communications
  • the capability of massive device-connectivity and sensing

Visitors to DOCOMO Open House 2020 will be able to view conceptual displays incorporating DOCOMO's vision of the evolution of 5G technologies into 6G. The event will take place in the Tokyo Big Sight exhibition complex in Tokyo on January 23 and 24. DOCOMO also plans to hold a panel session entitled "5G Evolution and 6G" on January 24.

Videos from Docomo Open House are embedded below, along with a previous talk by Takehiro Nakamura from 6G Summit.


6G has become a hot topic, especially after China announced back in November that they are working on 6G. We have some interesting tweets on 6G as well.

This one from Stefan Pongratz, Dell'Oro group shows the timeline for 5G, Pre-6G and 6G



This one provides a timeline all the way from Release 99 up till 21



Finally, here is a tweet highlighting the 6G research



Finally, the paper acknowledges the 5G challenges and focus areas for 5G evolution, before focusing on 6G.
The mmWave coverage and mobility needs improvement, while the downlink is able to provide very high data rates, the uplink is struggling to be better than 4G. Also, there are some very extreme requirements for industrial use cases, 5G has yet to prove that it can meet them.

Finally, here is another view from iDate Digiworld comparing 5G vs 6G in terms of performance, spectrum and network.



Related Posts:

Tuesday, 21 January 2020

How MOCN RAN-Sharing Works

Shared RAN deployment scenarios are an excellent opportunity for mobile network operators to lower their investments on both, network hardware and operational costs by sharing resources.

The MORAN approach where each operator continues to have its dedicated spectrum (= radio network cells) is easy to understand.

However, the Multi-Operator Core Network (MOCN) is a bit more complex, especially if one of the involved operators asks for service assurance KPIs that apply to its - and only its - subscribers. In this case it is a prerequisite to find out which "call" belongs to which core network operator to enable further KPI correlation and aggregation.

The figure below illustrates how this works:

(click on picture for larger version)

In the System Information Block (SIB) 1 of the cell a list of PLMN-IDs is broadcasted followed by a single Tracking Area Code (which can be combined each of the PLMN-IDs to get multiple TAIs) and a single Cell Identity.

Encoding is specified in 3GPP 36.331 (RRC) as follows:

SystemInformationBlockType1 ::=     SEQUENCE {
    cellAccessRelatedInfo              SEQUENCE {
       plmn-IdentityList                 PLMN-IdentityList,
       trackingAreaCode                  TrackingAreaCode,
       cellIdentity                      CellIdentity,

The spec further defines that the ECGI is the CellIdentiy combined with the first (!!!) PLMN-ID from the PLMN-ID List:

CellGlobalIdEUTRA field descriptions
cellIdentity
Identity of the cell within the context of the PLMN.
plmn-Identity
Identifies the PLMN of the cell as given by the first PLMN entry in the plmn-IdentityList in SystemInformationBlockType1.

So there is one and only 1 ECGI per radio cell in the network, but multiple PLMN-IDs and hence, multiple TAI, one fore each core network operator, are broadcasted.

During RRC establishement a particular UE signals on behalf on the selected PLMN-ID information element in the RRC Connection Setup Complete message to which core network operator shall be used.

This information is "translated" by the eNB into ECGI and TAI with different PLMN-IDs. While the ECGI displays the PLMN-ID of the operator that owns the RAN equipment the TAI shows the selected PLMN-ID of the UE's core network operator. 

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