Ultra Reliability: 5x9s (99.999%) in 3GPP Release-15 vs 6x9s (99.9999%) in 3GPP Release-16

We made a tutorial some time back explaining how to calculate reliability and what is the difference between 5x9s in 3GPP Release-15 5G vs 6x9s in 3GPP Release-16. Slides and video below

Beginners: Reliability - 5x9s vs 6x9s from 3G4G

Related posts:

• Updated 5G Terminology Presentation (Feb 2019)
• Prof. Andy Sutton: 5G Radio Access Network Architecture Evolution - Jan 2019
• Theoretical Throughput Calculation of FDD 5G New Radio (NR)
• Can Augmented & Mixed Reality be the Killer App 5G needs?
• What is Industrial IoT (IIoT) and how is it different from IoT?

Prof. Andy Sutton: 5G Radio Access Network Architecture Evolution - Jan 2019

Prof. Andy Sutton delivered his annual IET talk last month which was held the 6th Annual 5G conference. You can watch the videos for that event here (not all have been uploaded at the time of writing this post). His talks have always been very popular on this blog with the last year talk being 2nd most popular while the one in 2017 was the most popular one. Thanks also to IET for hosting this annual event and IET Tv for making this videos available for free.

The slides and video is embedded below but for new starters, before jumping to this, you may want to check out about 5G Network Architecture options in our tutorial here.

Prof. Andy Sutton: 5G RAN Architecture Evolution - Jan 2019 from 3G4G

As always, this is full of useful information with insight into how BT/EE is thinking about deploying 5G in UK.

Related Posts:

• Dr. Yue Wang: AI in 5G – the why and how - The 3G4G Blog
• CWHeritage Talk by Prof. Andy Sutton: The history of synchronisation in digital cellular networks - The 3G4G Blog
• Prof. Andy Sutton: 5G Network Architecture, Design and Optimisation - Jan 2018 - The 3G4G Blog
• 5G Network Architecture Options (Updated) - The 3G4G Blog
• 5G (IMT-2020) Wireless Resources - 3G4G Homepage

Nice short articles on 5G in 25th Anniversary Special NTT Docomo Technical Journal

5G has dominated the 3G4G blog for last few years. Top 10 posts for 2018 featured 6 posts on 5G while top 10 posts for 2017 featured 7. In makes sense to start 2019 posting with a 5G post.

A special 25th Anniversary edition of NTT Docomo Technical Journal features some nice short articles on 5G covering RAN, Core, Devices & Use cases. Here is some more details for anyone interested.

Radio Access Network in 5G Era introduces NTT Docomo's view of world regarding 5G, scenarios for the deployment of 5G and also prospects for further development of 5G in the future. The article looks at the main features in 5G RAN that will enable eMBB (Massive MIMO), URLLC (short TTI) and mMTC (eDRX).

Interested readers should also check out:

• Overview 3GPP 5G NR Physical Layer
• 5G NR Radio Protocols Overview
• 5G New Radio Standards and other Presentations

Core network for Social Infrastructure in 5G Era describes the principal 5G technologies required in the core network to realise new services and applications that will work through collaboration between various industries and businesses. It also introduces initiatives for more advanced operations, required for efficient operation of this increasingly complex network.

This article also goes in detail of the Services Based Architecture (SBA). In case you were wondering what UL CL and SSC above stands for; UpLink CLassifiers (UL CL) is a technology that identifies packets sent by a terminal to a specific IP address and routes them differently (Local Breakout) as can be seen above. It is generally to be used to connect to a MEC server. Session and Service Continuity (SSC) is used to decide if the IP address would be retained when the UE moves to a new area from the old one.

Interested readers should also check out:

• 5G Network Architecture Options (Updated)
• Tutorial: Service Based Architecture (SBA) for 5G Core (5GC)

Evolution of devices for the 5G Era discusses prospects for the high-speed, high-capacity, low-latency, and many-terminal connectivity features introduced with 5G, as well as advances in the network expected in the future, technologies that will be required for various types of terminal devices and the services, and a vision for devices in 2020 and thereafter.

According to the article, the medium term strategy of R&D division of NTT Docomo has three main themes: 5G, AI and Devices. In simple terms, devices will collect a lot of data which will become big data, 5G will be used to transport this data and the AI will process all the collected Big Data.

NTT Docomo has also redefined the devices as connecting through various technologies including cellular, Wi-Fi, Bluetooth & Fixed communications.

Interested readers should also check out:

• Benefits and Challenges of Applying Device-Level AI to 5G networks
• Short summary of #CWFDT event 'Smart Devices of 2025'

The final article on 5G, Views of the Future Pioneered by 5G: A World Converging the Strengths of Partners looks at field trials, partnerships, etc. In fact here the embedded video playlist below shows some of these use cases described in the article



In addition there are other articles too, but in this post I have focused on 5G only.

Nice article in 25th Anniversary special NTT Docomo technical journal - "History of Mobile Communications with a Look Back at NTT DOCOMO R&D and Outlook for the Future" - https://t.co/DolDIm15jL featuring @seizo_onoe pic.twitter.com/QVlpPXvFQS

— 3G4G (@3g4gUK) January 3, 2019

The 25th Anniversary Special Edition of NTT Docomo Technical Journal is available here.

5G Top-10 Misconceptions

Here is a video we did a few weeks back to clear the misconceptions about 5G. The list above summarizes the topics covered.



The video is nearly 29 minutes long. If you prefer a shorter version or are bored of hearing me 😜 then a summary version (just over 3 minutes) is in 3G4G tweet below.

Based on the comments received, here is our shorter version of "5G: Top 10 Misconceptions" video #UK5G #HWMBBFhttps://t.co/7lxE3ekDPM

— 3G4G (@3g4gUK) November 21, 2018

The slides can be downloaded from our Slideshare channel as always.

As always, we love your feedback, even when you strongly disagree.

Other interesting recent posts on 5G:

• 5G NR Radio Protocols Overview
• Overview 3GPP 5G NR Physical Layer
• 5G Development and Progress in Singapore
• 5G Network Architecture Options (Updated)
• Automated 4G / 5G HetNet Design
• Optus launching commercial 5G Fixed Wireless Access services in January 2019
• Benefits and Challenges of Applying Device-Level AI to 5G networks
• 5G New Radio Standards and other Presentations
• Base Station Antenna Considerations for 5G
• End-to-end Network Slicing in 5G
• ITU 'Network 2030': Initiative to support Emerging Technologies and Innovation looking beyond 5G advances

5G NR Radio Protocols Overview

3GPP held a workshop on 5G NR submission towards IMT-2020 last week. You can access all the agenda, documents, etc. on the 3GPP website here. You can also get a combined version of all presentations from the 3G4G website here. I also wrote a slightly detailed article on this workshop on 3G4G website here.

The following is nice overview of the 5G Radio Interface protocol as defined by 3GPP in NR Rel.15 by Sudeep Palat, Intel. The document was submitted to the 3GPP workshop on ITU submission in Brussels on Oct 24, 2018.

Overview 5G NR Radio Protocols by Intel from Eiko Seidel

The presentation discusses NR radio interface architecture and protocols for control and user plane; covering RRC, SDAP, PDCP, RLC and MAC, focussing on differences and performance benefits compared to LTE.  RRC states and state transitions with reduced transition delays are also discussed.

Related Posts:

• 3G4G: Workshop on 3GPP 5G NR submission towards IMT-2020
• 3GPP 5G – Briefing for Evaluation Groups
• 3G4G Blog: Overview 3GPP 5G NR Physical Layer

MAMS (Multi Access Management Services) at MEC integrating LTE and Wi-Fi networks

Came across Multi Access Management Services (MAMS) a few times recently so here is a quick short post on the topic. At present MAMS is under review in IETF and is being supported by Nokia, Intel, Broadcom, Huawei, AT&T, KT.

I heard about MAMS for the first time at a Small Cell Forum event in Mumbai, slides are here for this particular presentation from Nokia.

As you can see from the slide above, MAMS can optimise inter-working of different access domains, particularly at the Edge. A recent presentation from Nokia (here) on this topic provides much more detailed insight.

From the presentation:

•        MAMS (Multi Access Management Services) is a framework for

-            Integrating different access network domains based on user plane (e.g. IP layer) interworking,

-            with ability to select access and core network paths independently

-            and user plane treatment based on traffic types

-            that can dynamically adapt to changing network conditions

-            based on negotiation between client and network

•        The technical content is available as the following drafts*

-            Multi Access Management Services (MAMS) Framework – https://datatracker.ietf.org/doc/draft-kanugovi-intarea-mams-framework/

-            MAMS JSON definitions of Control Plane Messages: https://www.ietf.org/id/draft-agarwal-intarea-mams-protocol-json-00.txt

-            MAMS User Plane Specification: https://tools.ietf.org/html/draft-zhu-intarea-mams-user-protocol-02

*Currently under review, Co-authors: Nokia, Intel, Broadcom, Huawei, AT&T, KT,

The slides provide much more details, including the different use cases (pic below) for integrating LTE and Wi-Fi at the Edge.

Here are the references for anyone wishing to look at this in more detail:

• Multi Access Management Services (MAMS) Framework – https://datatracker.ietf.org/doc/draft-kanugovi-intarea-mams-framework/
• MAMS JSON definitions of Control Plane Messages: https://tools.ietf.org/html/draft-agarwal-intarea-mams-protocol-json-00
• MAMS User Plane Specification: https://tools.ietf.org/html/draft-zhu-intarea-mams-user-protocol-02

#CWHeritage Talk: The History of Synchronization in Digital Cellular Networks

CW (a.k.a. Cambridge Wireless) held a very interesting event titled 'Time for Telecoms' at the Science Museum in London. I managed to record this one talk by Prof. Andy Sutton, who has also kindly shared slides and some other papers that he mentions in his presentation. You can also see the tweets from the event on Twitter.

The video playlist and the presentation is embedded below.

The history of synchronisation in digital cellular networks from 3G4G

The papers referred to in the presentation/video available as follows:

• Martin Kingston: The need for Synchronisation in Telecommunications
• Charles Curry: Time from the Sky
• Sébastien Jobert & Kenneth Hann: Synchronisation and Time Distribution in Modern Telecommunications Networks
• Tommy Cook & Tim Frost: Stepping up to the Challenge on Tighter Time Accuracy.
• Andy Sutton: The history of synchronisation in digital cellular networks

5G Security Updates - March 2018

Its been a while since I wrote about 5G security in this fast changing 5G world. If you are new to 3GPP security, you may want to start with my tutorial here.

3GPP SA3 Chairman, Anand R. Prasad recently mentioned in his LinkedIn post:

5G security specification finalized! Paving path for new business & worry less connected technology use.

3GPP SA3 delegates worked long hours diligently to conclude the specification for 5G security standard during 26 Feb.-2 Mar. Several obstacles were overcome by focussed effort of individuals & companies from around the globe. Thanks and congrats to everyone!

All together 1000s of hours of work with millions of miles of travel were spent in 1 week to get the work done. This took 8 meetings (kicked off Feb. 2017) numerous on-line meetings and conference calls.

Excited to declare that this tremendous effort led to timely completion of 5G security specification (TS 33.501) providing secure services to everyone and everything!

The latest version of specs is on 3GPP website here.

ITU also held a workshop on 5G Security in Geneva, Switzerland on 19 March 2018 (link). There were quite a few interesting presentations. Below are some slides that caught my attention.

Major 5G Security Issues via Min Zuo, China Mobile #RANSplit #NetworkSlicing #SBA #NFV #SDN #CloudComputing #MEC pic.twitter.com/GD8EMNP1Fk

— 3G4G (@3g4gUK) March 20, 2018

The picture in the tweet above from China Mobile summarises the major 5G security issues very well. 5G security is going to be far more challenging than previous generations.

The presentation by Haiguang Wang, Huawei contained a lot of good technical information. The picture at the top is from that presentation and highlights the difference between 4G & 5G Security Architecture.

New entities have been introduced to make 5G more open.

EPS-AKA vs 5G-AKA (AKA = Authentication and Key Agreement) for trusted nodes

EAP-AKA' for untrusted nodes.

Slice security is an important topic that multiple speakers touched upon and I think it would continue to be discussed for a foreseeable future.

Dr. Stan Wing S. Wong from King’s College London has some good slides on 5G security issues arising out of Multi-Tenancy and Multi-Network Slicing.

Peter Schneider from Nokia-Bell Labs had good slides on 5G Security Overview for Programmable Cloud-Based Mobile Networks

Sander Kievit from TNO, a regular participant of working group SA3 of 3GPP on behalf of the Dutch operator KPN presented a view from 3GPP SA3 on the Security work item progress (slides). The slide above highlights the changes in 5G key hierarchy.

The ITU 5G Security Workshop Outcomes is available here.

ETSI Security Week 2018 will be held 11-15 June 2018. 5G security/privacy is one of the topics.

There is also 5GPPP Workshop on 5G Networks Security (5G-NS 2018), being held in Hamburg, Germany on August 27-30, 2018.

In the meantime, please feel free to add your comments & suggestions below.


Related Posts & Further Reading:

• Introduction to 3GPP Security in Mobile Cellular Networks - 3G4G
• 5G Security Updates - July 2017 - 3G4G
• 3GPP 5G Specifications - 3G4G
• Tutorial: Service Based Architecture (SBA) for 5G Core (5GC) - 3G4G

Control and User Plane Separation of EPC nodes (CUPS) in 3GPP Release-14

One of the items in 3GPP Rel-14 is Control and User Plane Separation of EPC nodes (CUPS). I have made a video explaining this concept that is embedded below.

In 3G networks (just considering PS domain), the SGSN and GGSN handles the control plane that is responsible for signalling as well as the user plane which is responsible for the user data. This is not a very efficient approach for deployment.

You can have networks that have a lot of signalling (remember signaling storm?) due to a lot of smartphone users but not necessarily consuming a lot of data (mainly due to price reasons). On the other hand you can have networks where there is not a lot of signalling but lot of data consumption. An example of this would be lots of data dongles or MiFi devices where users are also consuming a lot of data, because it’s cheap.

To cater for these different scenarios, the control plane and user plane was separated to an extent in the Evolved Packet Core (EPC). MME handles the control plane signalling while S-GW & P-GW handles the user plane

CUPS goes one step further by separating control & user plane from S-GW, P-GW & TDF. TDF is Traffic Detection Function which was introduced together with Sd reference point as means for traffic management in the Release 11. The Sd reference point is used for Deep Packet Inspections (DPI) purposes. TDF also provides the operators with the opportunity to capitalize on analytics for traffic optimization, charging and content manipulation and it works very closely with Policy and charging rules function, PCRF.

As mentioned, CUPS provides the architecture enhancements for the separation of S-GW, P-GW & TDF functionality in the EPC. This enables flexible network deployment and operation, by using either distributed or centralized deployment. It also allows independent scaling between control plane and user plane functions - while not affecting the functionality of the existing nodes subject to this split.

As the 3GPP article mentions, CUPS allows for:

• Reducing Latency on application service, e.g. by selecting User plane nodes which are closer to the RAN or more appropriate for the intended UE usage type without increasing the number of control plane nodes.
• Supporting Increase of Data Traffic, by enabling to add user plane nodes without changing the number of SGW-C, PGW-C and TDF-C in the network.
• Locating and Scaling the CP and UP resources of the EPC nodes independently.
• Independent evolution of the CP and UP functions.
• Enabling Software Defined Networking to deliver user plane data more efficiently.

The following high-level principles were also adopted for the CUPS:

• The CP function terminates the Control Plane protocols: GTP-C, Diameter (Gx, Gy, Gz).
• A CP function can interface multiple UP functions, and a UP function can be shared by multiple CP functions.
• An UE is served by a single SGW-CP but multiple SGW-UPs can be selected for different PDN connections. A user plane data packet may traverse multiple UP functions.
• The CP function controls the processing of the packets in the UP function by provisioning a set of rules in Sx sessions, i.e. Packet Detection Rules for packets inspection, Forwarding Action Rules for packets handling (e.g. forward, duplicate, buffer, drop), Qos Enforcement Rules to enforce QoS policing on the packets, Usage Reporting Rules for measuring the traffic usage.
• All the 3GPP features impacting the UP function (PCC, Charging, Lawful Interception, etc) are supported, while the UP function is designed as much as possible 3GPP agnostic. For example, the UPF is not aware of bearer concept.
• Charging and Usage Monitoring are supported by instructing the UP function to measure and report traffic usage, using Usage Reporting Rule(s). No impact is expected to OFCS, OCS and the PCRF.
• The CP or UP function is responsible for GTP-u F-TEID allocation.
• A legacy SGW, PGW and TDF can be replaced by a split node without effecting connected legacy nodes.

CUPS forms the basis of EPC architecture evolution for Service-Based Architecture for 5G Core Networks. More in another post soon.

A short video on CUPS below, slides available here.



Further reading:

• 3GPP: Control and User Plane Separation of EPC nodes (CUPS)
• ITU: 5G Network Architecture and FMC - Joe Wilke, Ericsson
• Heavy Reading: Service-Based Architecture for 5G Core Networks

Quick tutorial on Mobile Network Sharing Options

Here is a quick tutorial on mobile network sharing approaches, looking at site/mast sharing, MORAN, MOCN and GWCN. Slides and video embedded below. If for some reason you prefer direct link to video, its here.

Mobile Network Sharing from 3G4G

See also:

• Telecoms Infrastructure Blog: Passive and Active Infrastructure Sharing
• Telecoms Infrastructure Blog: Small Cells Network Sharing
• The 3G4G Blog: Network Sharing is becoming more relevant with 5G
• The 3G4G Blog: A practical use of MOCN in ESN

A quick starter on 4G voice (for beginners)

I recently did a 4G voice presentation for beginners after realizing that even though so many years have passed after VoLTE was launched, people are still unsure how it works or how its different from CS Fallback.

There are many other posts that discuss these topics in detail on this blog (follow the label) or on 3G4G website. Anyway, here is the video:

The slides are available on 3G4G Slideshare account here. More similar training videos are available here.

Enhanced 5G Security via IMSI Encryption

Source: North Star Post

IMSI Catchers can be a real threat. It doesn't generally affect anyone unless someone is out to get them. Nevertheless its a security flaw that is even present in LTE. This presentation here is a good starting point on learning about IMSI Catcher and the one here about privacy and availability attacks.

This article by Ericsson is a good starting point on how 5G will enhance security by IMSI encryption. From the article:

The concept we propose builds on an old idea that the mobile device encrypts its IMSI using home network’s asymmetric key before it is transmitted over the air-interface. By using probabilistic asymmetric encryption scheme – one that uses randomness – the same IMSI encrypted multiple times results in different values of encrypted IMSIs. This makes it infeasible for an active or passive attacker over the air-interface to identify the subscriber. Above is a simplified illustration of how a mobile device encrypts its IMSI. 

Each mobile operator (called the ‘home network’ here) has a public/private pair of asymmetric keys. The home network’s private asymmetric key is kept secret by the home network, while the home network’s public asymmetric key is pre-provisioned in mobile devices along with subscriber-specific IMSIs (Step 0). Note that the home network’s public asymmetric key is not subscriber-specific. 

For every encryption, the mobile device generates a fresh pair of its own public/private asymmetric keys (Step 1). This key pair is used only once, hence called ephemeral, and therefore provide probabilistic property to the encryption scheme. As shown in the figure, the mobile device then generates a new key (Step 2), e.g., using Diffie–Hellman key exchange. This new key is also ephemeral and is used only once to encrypt the mobile device’s IMSI (Step 3) using symmetric algorithm like AES. The use of asymmetric and symmetric crypto primitives as described above is commonly known as integrated/hybrid encryption scheme. The Elliptic Curve Integrated Encryption Scheme (ECIES) is a popular scheme of such kind and is very suitable to the use case of IMSI encryption because of low impact on radio bandwidth and mobile device’s battery. 

The nicest thing about the described concept is that no public key infrastructure is necessary, which significantly reduces deployment complexity, meaning that mobile operators can start deploying IMSI encryption for their subscribers without having to rely on any external party or other mobile operators.

'3GPP TR 33.899: Study on the security aspects of the next generation system' lists one such approach.

The Key steps are as follows:

1. UE is configured with 5G (e)UICC with ‘K’ key, the Home Network ID, and its associated public key.
2. SEAF send Identity Request message to NG-UE. NG-UE considers this as an indication to initiate Initial Authentication.
3. NG-UE performs the following:
1. Request the (e)UICC application to generate required security material for initial authentication, RANDUE, , COUNTER, KIARenc, and KIARInt.
2. NG-UE builds IAR as per MASA. In this step NG-UE includes NG-UE Security Capabilities inside the IAR message. It also may include its IMEI. 
3. NG-UE encrypts the whole IAR including the MAC with the home network public key.
4. NG-UE sends IAR to SEAF.
4. Optionally, gNB-CP node adds its Security Capabilities to the transposrt message between the gNB-CP and the SEAF (e.g., inside S1AP message as per 4G).
5. gNB-CP sends the respective S1AP message that carries the NG-UE IAR message to the SEAF.
6. SEAF acquirs the gNB-CP security capabilities as per the listed options in clause 5.2.4.12.4.3and save them as part of the temporary context for the NG-UE.
7. SEAF follows MASA and forward the Authentication and Data Request message to the AUSF/ARPF.
8. When AUSF/ARPF receives the Authentication and Data Request message, authenticates the NG-UE as per MASA and generates the IAS respective keys. AUSF/ARPF may recover the NG-UE IMSI and validate the NG-UE security capabilities.
9. AUSF/ARPF sends Authentication and Data Response to the SEAF as per MASA with NG-UE Security Capabilities included.
10. SEAF recovers the Subscriber IMSI, UE security Capabilities, IAS keys, RANDHN, COUNTER and does the following:
1. Examine the UE Security Capabilities and decides on the Security parameters.
2. SEAF may acquire the UP-GW security capabilities at this point after receiving the UP-GW identity from AUSF/ARPF or allocate it dynamically through provisioning and load balancing.
11. SEAF builds IAS and send to the NG-UE following MASA. In addition, SEAF include the gNB-CP protocol agreed upon security parameters in the S1AP message being sent to the gNB-CP node.
12. gNB-CP recovers gNB-CP protocol agreed upon security parameters and save it as part of the NG-UE current context.
13. gNB-CP forwards the IAS message to the NG-UE.
14. NG-UE validates the authenticity of the IAS and authenticates the network as per MASA. In addition, the UE saves all protocols agreed upon security parameters as part of its context. NG-UE sends the Security and Authentication Complete message to the SEAF.
15. SEAF communicates the agreed upon UP-GW security parameters to the UP-GW during the NG-UE bearer setup.

ARPF - Authentication Credential Repository and Processing Function 
AUSF - Authentication Server Function 
SCMF - Security Context Management Function
SEAF - Security Anchor Function
NG-UE - NG UE
UP - User Plane 
CP - Control Plane
IAR - Initial Authentication Request 
IAS - Initial Authentication Response
gNB - Next Generation NodeB

You may also want to refer to the 5G Network Architecture presentation by Andy Sutton for details.

See also:

• 5G Security Updates - July 2017
• 5G: Architecture, QoS, gNB, Specifications - April 2017 Update
• 5G – Beyond the Hype
• 5G Network Architecture and Design Update - Jan 2017

Second thoughts about LTE-U / LAA

Its been a while since I wrote about LTE-U / LAA on this blog. I have written a few posts on the small cells blog but they seem to be dated as well. For anyone needing a quick refresher on LTE-U / LAA, please head over to IoTforAll or ShareTechNote. This post is not about the technology per se but the overall ecosystem with LTE-U / LAA (and even Multefire) being part of that.

Lets recap the market status quickly. T-Mobile US has already got LTE-U active and LAA was tested recently. SK Telecom achieved 1Gbps in LAA trials with Ericsson. AT&T has decided to skip the non-standard LTE-U and go to standards based LAA. MTN & Huawei have trialled LAA for in-building in South Africa. All these sound good and inspires confidence in the technology however some observations are worrying me.

Couple of years back when LTE-U idea was conceived, followed by LAA, the 5GHz channels were relatively empty. Recently I have started to see that they are all filling up.

The 5GHz spectrum is already getting congested, how will #MulteFire fit in this? #WGCLon pic.twitter.com/cqNkBwJZN4

— Zahid Ghadialy (@zahidtg) May 10, 2017

Any malls, hotels, service stations or even big buildings I go to, they all seem to be occupied. While supplemental downlink channels are 20MHz each, the Wi-Fi channels could be 20MHz, 40MHz, 80MHz or even 160MHz.

On many occasions I had to switch off my Wi-Fi as the speeds were so poor (due to high number of active users) and go back to using 4G. How will it impact the supplemental downlink in LTE-U / LAA? How will it impact the Wi-Fi users?

On my smartphone, most days I get 30/40Mbps download speeds and it works perfectly fine for all my needs. The only reason we would need higher speeds is to do tethering and use laptops for work, listen to music, play games or watch videos. Most people I know or work with dont require gigabit speeds at the moment.

Once a user that is receiving high speeds data on their device using LTE-U / LAA creates a Wi-Fi hotspot, it may use the same 5GHz channels as the ones that the network is using for supplemental downlink. How do you manage this interference? I am looking forward to discussions on technical fora where users will be asking why their download speeds fall as soon as they switch Wi-Fi hotspot on.

The fact is that in non-dense areas (rural, sub-urban or even general built-up areas), operators do not have to worry about the network being overloaded and can use their licensed spectrum. Nobody is planning to deploy LTE-U / LAA in these areas. In dense and ultra-dense areas, there are many users, many Wi-Fi access points, ad-hoc Wi-Fi networks and many other sources of interference. In theory LTE-U / LAA can help significantly but as there are many sources of interference,its uncertain if it would be a win-win for everyone or just more interference for everyone to deal with.

Further reading:

• Unlicensed LTE Explained – LTE-U vs. LAA vs. LWA vs. Multefire
• LTE-U(LTE-Unlicensed) / LAA / LWA / MultiPath / MulteFire /LTE-R (LTE-Railway)
• Ruckus Wireless LTE Operation in Unlicensed Spectrum [Video]
• 160 MHz channels in 802.11ac wave 2
• MulteFire: A double-edged sword

Network Sharing is becoming more relevant with 5G

5G is becoming a case of 'damned if you do damned if you don't'. Behind the headlines of new achievements and faster speeds lies the reality that many operators are struggling to keep afloat. Indian and Nigerian operators are struggling with heavy debt and it wont be a surprise if some of the operators fold in due course.

With increasing costs and decreasing revenues, its no surprise that operators are looking at ways of keeping costs down. Some operators are postponing their 5G plans in favour of Gigabit LTE. Other die hard operators are pushing ahead with 5G but looking at ways to keep the costs down. In Japan for example, NTT DOCOMO has suggested sharing 5G base stations with its two rivals to trim costs, particularly focusing efforts in urban areas.

In this post, I am looking to summarise an old but brilliant post by Dr. Kim Larsen here. While it is a very well written and in-depth post, I have a feeling that many readers may not have the patience to go through all of it. All pictures in this post are from the original post by Dr. Kim Larsen.

Before embarking on any Network sharing mission, its worthwhile asking the 5W's (Who, Why, What, Where, When) and 2H's (How, How much).

• Why do you want to share?
• Who to share with? (your equal, your better or your worse).
• What to share? (sites, passives, active, frequencies, new sites, old sites, towers, rooftops, organization, ,…).
• Where to share? (rural, sub-urban, urban, regional, all, etc..).
• When is a good time to start sharing? During rollout phase, steady phase or modernisation phase. See picture below. For 5G, it would make much more sense that network sharing is done from the beginning, i.e., Rollout Phase

• How to do sharing?. This may sound like a simple question but it should take account of regulatory complexity in a country. The picture below explains this well:

• How much will it cost and how much savings can be attained in the long term? This is in-fact a very important question because the end result after a lot of hard work and laying off many people may result in an insignificant amount of cost savings. Dr. Kim provides detailed insight on this topic that I find it difficult to summarise. Best option is to read it on his blog.

An alternative approach to network sharing is national roaming. Many European operators are dead against national roaming as this means the network loses its differentiation compared to rival operators. Having said that, its always worthwhile working out the savings and seeing if this can actually help.

National Roaming can be attractive for relative low traffic scenarios or in case were product of traffic units and national roaming unit cost remains manageable and lower than the Shared Network Cost.

The termination cost or restructuring cost, including write-off of existing telecom assets (i.e., radio nodes, passive site solutions, transmission, aggregation nodes, etc….) is likely to be a substantially financial burden to National Roaming Business Case in an area with existing telecom infrastructure. Certainly above and beyond that of a Network Sharing scenario where assets are being re-used and restructuring cost might be partially shared between the sharing partners.

Obviously, if National Roaming is established in an area that has no network coverage, restructuring and termination cost is not an issue and Network TCO will clearly be avoided, Albeit the above economical logic and P&L trade-offs on cost still applies.

If this has been useful to understand some of the basics of network sharing, I encourage you to read the original blog post as that contains many more details.

Futher Reading:

• Fundamentals of Mobile Network Sharing
• The ABC of Network Sharing – The Fundamentals (Part I).

Theoretical calculation of EE's announcement for 429Mbps throughput

The CEO of UK mobile network operator EE recently announced on twitter that they have achieved 429 Mbps in live network. The following is from their press release:

EE, the UK’s largest mobile network operator and part of the BT Group, has switched on the next generation of its 4G+ network and demonstrated live download speeds of 429Mbps in Cardiff city centre using Sony’s Xperia XZ Premium, which launched on Friday 2 June. 

The state of the art network capability has been switched on in Cardiff and the Tech City area of London today. Birmingham, Manchester and Edinburgh city centres will have sites upgraded during 2017, and the capability will be built across central London. Peak speeds can be above 400Mbps with the right device, and customers connected to these sites should be able to consistently experience speeds above 50Mbps. 

Sony’s Xperia XZ Premium is the UK’s first ‘Cat 16’ smartphone optimised for the EE network, and EE is the only mobile network upgrading its sites to be able to support the new device’s unique upload and download capabilities. All devices on the EE network will benefit from the additional capacity and technology that EE is building into its network. 

... 

The sites that are capable of delivering these maximum speeds are equipped with 30MHz of 1800MHz spectrum, and 35MHz of 2.6GHz spectrum. The 1800MHz carriers are delivered using 4x4 MIMO, which sends and receives four signals instead of just two, making the spectrum up to twice as efficient. The sites also broadcast 4G using 256QAM, or Quadrature Amplitude Modulation, which increases the efficiency of the spectrum.

Before proceeding further you may want to check out my posts 'Gigabit LTE?' and 'New LTE UE Categories (Downlink & Uplink) in Release-13'

If you read the press release carefully, EE are now using 65MHz of spectrum for 4G. I wanted to provide a calculation for whats possible in theory with this much bandwidth.

Going back to basics (detailed calculation for basics in slideshare below), in LTE/LTE-A, the maximum bandwidth possible is 20MHz. Any more bandwidth can be used with Carrier Aggregation. So as per the EE announcement, its 20 + 10 MHz in 1800 band and 20 + 15 MHz in 2600 band

So for 1800 MHz band:

50 resource blocks (RBs) per 10MHZ, 150 for 30MHz.
Each RB has 12x7x2=168 symbols per millisecond in case of normal modulation support cyclic prefix (CP).
For 150 RBs, 150 x 168 = 25200 symbols per ms or 25,200,000 symbols per second. This can also be written as 25.2 Msps (Mega symbols per second)
256 QAM means 8 bits per symbol. So the calculation changes to 25.2 x 8 = 201.6 Mbps. Using 4 x 4 MIMO, 201.6 x 4 = 806.4Mbps
Removing 25% overhead which is used for signalling, this gives 604.80 Mbps


Repeating the same exercise for 35MHz of 2600 MHz band, with 2x2 MIMO and 256 QAM:

175 x 168 = 29400 symbols per ms or 29,400,000 symbols per second. This can be written as 29.4 Msps
29.4 x 8 = 235.2 Mbps
Using 2x2 MIMO, 235.2 x 2 = 470.4 Mbps
Removing 25% overhead which is used for signalling, this gives 352.80 Mbps

The combined theoretical throughput for above is 957.60 Mbps

For those interested in revisiting the basic LTE calculations, here is an interesting document:

Further reading:

• 5G SpeedTests and Theoretical Max Speeds Calculations
• LTE Peak Capacity Explained: How to Calculate it? - Frank Rayal
• Gigabit LTE?
• New LTE UE Categories (Downlink & Uplink) in Release-13