Debugging Problem: Same Phones With Different Signal Levels?

I have discussed this problem in past, based on questions asked on various fora (example). Here is a video I made some weeks back. Will be interested to know what other reasons people can come up with 😊.

5G Core Network, System Architecture & Registration Procedure

The 5G System architecture (based on 3GPP TS 23.501: System Architecture for the 5G System; Stage 2) consists of the following network functions (NF). The functional description of these network functions is specified in clause 6.
- Authentication Server Function (AUSF)
- Core Access and Mobility Management Function (AMF)
- Data network (DN), e.g. operator services, Internet access or 3rd party services
- Structured Data Storage network function (SDSF)
- Unstructured Data Storage network function (UDSF)
- Network Exposure Function (NEF)
- NF Repository Function (NRF)
- Network Slice Selection Function (NSSF)
- Policy Control function (PCF)
- Session Management Function (SMF)
- Unified Data Management (UDM)
- Unified Data Repository (UDR)
- User plane Function (UPF)
- Application Function (AF)
- User Equipment (UE)
- (Radio) Access Network ((R)AN)

As you can see, this is slightly more complex than the 2G/3G/4G Core Network Architecture.

Alan Carlton, Vice President, InterDigital and Head of InterDigital International Labs Organization spanning Europe and Asia provided a concise summary of the changes in 5G core network in ComputerWorld:

Session management is all about the establishment, maintenance and tear down of data connections. In 2G and 3G this manifested as the standalone General Packet Radio Service (GPRS). 4G introduced a fully integrated data only system optimized for mobile broadband inside which basic telephony is supported as just one profile.

Mobility management as the name suggests deals with everything that needs doing to support the movement of users in a mobile network. This encompasses such functions as system registration, location tracking and handover. The principles of these functions have changed relatively little through the generations beyond optimizations to reduce the heavy signaling load they impose on the system.

The 4G core network’s main function today is to deliver an efficient data pipe. The existence of the service management function as a dedicated entity has been largely surrendered to the “applications” new world order. Session management and mobility management are now the two main functions that provide the raison d’etre for the core network.

Session management in 4G is all about enabling data connectivity and opening up a tunnel to the world of applications in the internet as quickly as possible. This is enabled by two core network functions, the Serving Gateway (SGW) and Packet Data Gateway (PGW). Mobility management ensures that these data sessions can be maintained as the user moves about the network. Mobility management functions are centralized within a network node referred to as Mobility Management Entity (MME). Services, including voice, are provided as an “app” running on top of this 4G data pipe. The keyword in this mix, however, is “function”. It is useful to highlight that the distinctive nature of the session and mobility management functions enables modularization of these software functions in a manner that they can be easily deployed on any Commercial-Off-The-Shelf (COTS) hardware.

The biggest change in 5G is perhaps that services will actually be making a bit of a return...the plan is now to deliver the whole Network as a Service. The approach to this being taken in 3GPP is to re-architect the whole core based on a service-oriented architecture approach. This entails breaking everything down into even more detailed functions and sub-functions. The MME is gone but not forgotten. Its former functionality has been redistributed into precise families of mobility and session management network functions. As such, registration, reachability, mobility management and connection management are all now new services offered by a new general network function dubbed Access and Mobility Management Function (AMF). Session establishment and session management, also formerly part of the MME, will now be new services offered by a new network function called the Session Management Function (SMF). Furthermore, packet routing and forwarding functions, currently performed by the SGW and PGW in 4G, will now be realized as services rendered through a new network function called the User Plane Function (UPF).

The whole point of this new architectural approach is to enable a flexible Network as a Service solution. By standardizing a modularized set of services, this enables deployment on the fly in centralized, distributed or mixed configurations to enable target network configurations for different users. This very act of dynamically chaining together different services is what lies at the very heart of creating the magical network slices that will be so important in 5G to satisfy the diverse user demands expected. The bottom line in all this is that the emphasis is now entirely on software. The physical boxes where these software services are instantiated could be in the cloud or on any targeted COTS hardware in the system. It is this intangibility of physicality that is behind the notion that the core network might disappear in 5G.

3GPP TS 23.502: Procedures for the 5G System; Stage 2, provides examples of signalling for different scenarios. The MSC above shows the example of registration procedure. If you want a quick refresher of LTE registration procedure, see here.

I dont plan to expand on this procedure here. Checkout section "4.2.2 Registration Management procedures" in 23.502 for details. There are still a lot of FFS (For further studies 😉) in the specs that will get updated in the coming months.


Further Reading:

• 3GPP TR 23.799: Study on Architecture for Next Generation System
• 3GPP TS 23.501: System Architecture for the 5G System; Stage 2
• 3GPP TS 23.502: Procedures for the 5G System; Stage 2

Nokia Bell Labs - Future Impossible Series Videos

Picture Source: Cnet

Bell Labs, which has played a significant role in telecoms history and has a very glorious list of achievements created a collection of short films highlighting the brilliant minds who created the invisible nervous system of our society. Some of you may be aware that Bell Labs is now a part of Nokia but was previously part of Alcatel-Lucent, Lucent and AT&T before that.

The playlist with 5 videos is embedded below and short details of the videos follows that.


Video 1: Introduction

Introducing 'Future Impossible', a collection of short films highlighting the brilliant minds who created the invisible nervous system of our society, a fantastic intelligent network of wires and cables undergirding and infiltrating every aspect of modern life.


Video 2: The Shannon Limit

In 1948, father of communications theory Claude Shannon developed the law that dictated just how much information could ever be communicated down any path, anywhere, using any technology. The maximum rate of this transmission would come to be known as the Shannon Limit.  Researchers have spent the following decades trying to achieve this limit and to try to go beyond it.


Video 3: The Many Lives of Copper

In the rush to find the next generation of optical communications, much of our attention has moved away from that old standby, copper cabling. But we already have miles and miles of the stuff under our feet and over our heads. What if instead of laying down new optical fiber cable everywhere, we could figure out a way to breathe new life into copper and drive the digital future that way?


Video 4: The Network of You

In the future, every human will be connected to every other human on the planet by a wireless network. But that’s just the beginning. 

Soon the stuff of modern life will all be part of the network, and it will unlock infinite opportunities for new ways of talking, making and being. The network will be our sixth sense, connecting us to our digital lives. In this film, we ponder that existence and how it is enabled by inventions and technologies developed over the past 30 years, and the innovations that still lie ahead of us.


Video 5: Story of Light

When Alexander Graham Bell discovered that sound could be carried by light, he never could have imagined the millions of written text and audio and video communications that would one day be transmitted around the world every second on a single strand of fiber with the dimensions of a human hair.

Follow the journey of a single text message zipping around the globe at the speed of light, then meet the researchers that have taken up Bell’s charge.


For anyone interested, Wikipedia has a good detailed info on Bell Labs history here.

Bluetooth 5 for IoT

Bluetooth 5 (not 5.0 - to simplify marketing messages and communication) was released last year. The main features being 2x Faster, 4x Range (Bluetooth 4 - 50m outdoors, 10m Indoors; Bluetooth 5 - 200m outdoors, 40m indoors) & 8x Data.

I like this above slide by Robin Heydon, Qualcomm from a presentation he gave in CW (Cambridge Wireless) earlier this year. What is highlights is that Bluetooth 5 is Low Energy (LE) like its predecessor 4.0.For anyone interested, a good comparison of 5 vs 4.2 is available here.

In addition, Mesh support is now available for Bluetooth. I assume that this will work with Bluetooth 4.0 onwards but it would probably only make sense from Bluetooth 5 due to support for reasonable range.

The Bluetooth blog has a few posts on Mesh (see here, here and here). I like this simple introductory video below.


This recent article by Geoff Varral on RTT says the following (picture from another source):

Long distance Bluetooth can also be extended with the newly supported mesh protocol.

This brings Bluetooth into direct competition with a number of other radio systems including 802.15,4 based protocols such as Zigbee, LoRa, Wireless-M (for meter reading), Thread and 6 LowPAN (IPV6 over local area networks. 802.11 also has a mesh protocol and long distance ambitions including 802.11ah Wi-Fi in the 900 MHz ISM band. It also moves Bluetooth into the application space targeted by LTE NB IOT and LTE M though with range limitations.

There are some interesting design challenges implied by 5.0. The BLE specification is inherently less resilient to interference than Classic or EDR Bluetooth. This is because the legacy seventy eight X 1 MHz channels within the 20 MHz 2.4 GHz pass band are replaced with thirty nine two MHz channels with three fixed non hopping advertising channels in the middle and edge of the pass band.

These have to withstand high power 20 MHz LTE TDD in Band 40 (below the 2.4 GHz pass band) and high power 20 MHz LTE TDD in band 41 above the pass band (and Band 7 LTE FDD). This includes 26 dBm high power user equipment.

The coexistence of Bluetooth, Wi-Fi and LTE has been intensively studied and worked on for over ten years and is now managed with surprising effectiveness within a smart phone through a combination of optimised analogue and digital filtering (SAW and FBAR filters) and time domain interference mitigation based on a set of  industry standard wireless coexistence protocols.

The introduction of high power Bluetooth however implies that this is no longer just a colocation issue but potentially a close location issue. Even managing Bluetooth to Bluetooth coexistence becomes a non-trivial task when you consider that +20 dBm transmissions will be closely proximate to -20 dBm or whisper mode -30 dBm transmissions and RX sensitivity of -93 dBm, potentially a dynamic range of 120dB. Though Bluetooth is a TDD system this isolation requirement will be challenging and vulnerable to ISI distortion. 

More broadly there is a need to consider how ‘5G Bluetooth’ couples technically and commercially with 5G including 5G IOT

Ericsson has a whitepaper on Bluetooth Mesh Networking. The conclusion of that agrees that Bluetooth may become a relevant player in IoT:

Bluetooth mesh is a scalable, short-range IoT technology that provides flexible and robust performance. The Bluetooth Mesh Profile is an essential addition to the Bluetooth ecosystem that enhances the applicability of Bluetooth technology to a wide range of new IoT use cases. Considering the large Bluetooth footprint, it has the potential to be quickly adopted by the market. 

With proper deployment and configuration of relevant parameters of the protocol stack, Bluetooth mesh is able to support the operation of dense networks with thousands of devices. The building automation use case presented in this white paper shows that Bluetooth mesh can live up to high expectations and provide the necessary robustness and service ratio. Furthermore, the network design of Bluetooth mesh is flexible enough to handle the introduction of managed operations on top of flooding, to further optimize behavior and automate the relay selection process.

Moreover, another Ericsson article says that "smartphones with built-in Bluetooth support can be part of the mesh, may be used to configure devices and act as capillary gateways."

A capillary network is a LAN that uses short-range radio-access technologies to provide groups of devices with wide area connectivity. Capillary networks therefore extend the range of the wide area mobile networks to constraint devices. Figure above illustrates the Bluetooth capillary gateway concept.

Once there are enough smartphones and Bluetooth devices with Bluetooth 5 and Mesh support, It would be interesting to see how developers use it. Would also be interesting to see if it will start encroaching LoRa and Sigfox markets as well.

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

AT&T Blog: "Providing Connectivity from Inside a Cactus"

A recent AT&T blog post looks at how the fake cactus antennas are manufactured. I also took a closeup of a fake cactus antenna when I went to a Cambridge Wireless Heritage SIG event as can be seen in tweet below.

I also spotted a fake base station at @sciencemuseum 👀📶😎 #CWWH pic.twitter.com/avyiIqte64

— Zahid Ghadialy (@zahidtg) April 29, 2017

The blog says:

To make a stealth site look as real as possible, our teams use several layers of putty and paint. Our goal is to get the texture and color just right, but also ensure it can withstand natural elements – from snowy Colorado to blistering Arizona. 

Tower production takes 6-8 weeks and starts with constructing a particular mold. The molds quickly become 30-foot tall saguaro cacti or 80-foot tall redwood trees.But these aren’t just steel giants. 

The materials that cover the stealth antennas, like paint or faux-leaves, must be radio frequency-friendly. Stealth antennas designed to look like church steeples or water towers are mostly made of fiberglass. This lets the signal from the antennas penetrate through the casing. 

These stealth deployments are just one of the many unique ways we provide coverage to our customers. So take a look outside, your connection may be closer than you think—hidden in plain sight!

This videos gives a good idea


If this is a topic of interest, then have a look at this collection of around 100 antennas:

Antennas: A Collection from 3G4G

See also:

• Different types of Mobile Masts
• The Art of Disguising Cellular Antennas
• Disguising Small Cells in Rural areas

Mobile can help with United Nations SDGs, only if prices go down

I came across this interesting article in WSJ, courtesy of the Benedict Evans newsletter, which discusses how Indians are using their smartphones even more and consuming far more data than they previously did. Due to low incomes, spending money on mobile top-up is to the detriment of other sectors. To quote the article:

“There was a time when kids would come here and blow their pocket money on chips and chocolate,” said Anup Kapoor, who runs a mom-and-pop grocery shop in New Delhi. These days, “they spend every last rupee on a data recharge instead.”

United Nations have created 17 very ambitious Sustainable Development Goals (SDGs) that universally apply to all, countries will mobilize efforts to end all forms of poverty, fight inequalities and tackle climate change, while ensuring that no one is left behind.

The SDGs, also known as Global Goals, build on the success of the Millennium Development Goals (MDGs) and aim to go further to end all forms of poverty. The new Goals are unique in that they call for action by all countries, poor, rich and middle-income to promote prosperity while protecting the planet. They recognize that ending poverty must go hand-in-hand with strategies that build economic growth and addresses a range of social needs including education, health, social protection, and job opportunities, while tackling climate change and environmental protection.

I have talked about Rural connectivity on this blog and a lot more on small cells blog. In fact the heart touching end user story from Rural England was shared multiple times on different platforms. GSMA has done a good amount of work with the rural communities with their mobile for development team and have some interesting videos showing positive impacts of bringing connectivity to rural communities in Tanzania (see here and here).

While you will always hear about the challenges in bringing connectivity to these rural communities, all technological challenges can be solved. There are many highly ambitious projects using balloons, drones, creating droneways, Helikites, Satellite backhaul, drone based backhaul, mmWave backhaul, etc. The real problem to solve here are the costs (spectrum, infrastructure, etc.) and the end-user pricing.

Coming back to the first story of this post about India, when given an option about selecting mobile data or shampoo, people will probably choose mobile data. What about mobile data vs food? While there are some innovative young companies that can help bring the costs down, there is still a big hurdle to leap in terms of convincing the operators mindsets, bureaucracy, etc.

To help explain my point lets look at an excerpt from this article in Wired:

It’s the kind of problem that Vanu Bose, the founder of the small cell network provider CoverageCo, has been trying to solve with a new, ultra-energy-efficient mobile technology. Bose chose two places to pilot this tech: Vermont and Rwanda. “We picked these two locations because we knew they would be challenging in terrain and population density,” he says. “What we didn’t expect was that many of the problems were the same in Rwanda and Vermont—and in fact the rollout has been much easier in Africa.”

The good news is that things are changing. Parallel Wireless (see disclosure at the bottom) is one such company trying to simplify network deployment and at the same time bring the costs down. In a recent deployment with Ice Wireless in Canada, this was one of the benefit to the operator. To quote from MobileSyrup:

A radio access network is one of the key components in the architecture of any wireless network. RANs sit between consumer-facing devices like smartphones and computers and the core network, helping connect those devices to the larger network.  

Essentially where the likes of Nokia and Huawei ask clients to buy an expensive hardware component for their RAN needs, Parallel Wireless offers allows companies like Ice Wireless to use off-the-shelf computer and server components to emulate a RAN. The company also sells wireless base stations like the two pictured above that are smaller than the average cell tower one sees in cities and less remote parts of the country.  

Besides reducing the overall price of a network deployment, Parallel’s components present several other advantages for a company like Ice Wireless.  

For instance, small base stations make it easier for the company to build redundancies into its network, something that’s especially important when a single arctic snowstorm can knock out wireless service for thousands of people.

These kind of benefits allow operators to pass on the cost reduction thereby allowing the price reduction for end users. In case of Ice Wireless, they have already got rid of roaming charges and have started offering unlimited data plans for the communities in Canada's North.

Finally, to quote David Nabarro, Special Adviser of the United Nations Secretary-General on the 2030 Agenda for Sustainable Development from the GSMA 2016 Mobile Industry Impact Report: Sustainable Development Goals:

Achieving the SDGs demands new technologies, innovations, and data collection that can integrate and complement traditional statistics. A driving force behind this data revolution is mobile technology. 

Mobile phone technology has already transformed societies around the globe, even the poorest countries and communities. It is helping to empower women, create jobs, spur financial independence, improve education, boost agriculture production, and promote better health. Mobile phones have enabled communities to monitor elections, hold governments accountable, and save lives in natural disasters. 

As we focus on implementing the Sustainable Development Goals, the mobile industry has a critical role in working with governments and the international community to expand connectivity, to lower barriers to access, and to ensure that tools and applications are developed with vulnerable communities in mind. 

With 5G just round the corner, I hope that the operators and vendors will be able to get their costs down, resulting in lower end-user prices. That would be a win-win for everyone.

*Full Disclosure: I work for Parallel Wireless as a Senior Director, Strategic Marketing. 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.

5G Security Updates - July 2017

Its been nearly 2 years since I last blogged about ETSI Security workshop. A lot has changed since then, especially as 5G is already in the process of being standardised. This is in addition to NFV / SDN that also applied to 4G networks.

ETSI Security Week (12 - 16 June) covered lot more than 5G, NFV, SDN, etc. Security specialists can follow the link to get all the details (if they were not already aware of).

I want to quickly provide 3 links so people can find all the useful information:

NFV Security Tutorial, designed to educate attendees on security concerns facing operators and providers as they move forward with implementing NFV. While the topics are focused on security and are technical in nature we believe any individual responsible for designing, implementing or operating a NFV system in an organization will benefit from this session. Slides here.

NFV Security: Network Functions Virtualization (NFV), leveraging cloud computing, is set to radically change the architecture, security, and implementation of telecommunications networks globally. The NFV Security day will have a sharp focus on the NFV security and will bring together the world-wide community of the NFV security leaders from the industry, academia, and regulators. If you want to meet the movers and shakers in this field, get a clear understanding of the NFV security problems, challenges, opportunities, and the state of the art development of security solutions, this day is for you. Slides here.

5G Security: The objectives of this event are to:

• Gather different actors involved in the development of 5G, not only telecom, and discuss together how all their views will shape together in order to understand the challenges, threats and the security requirements that the 5G scenarios will be bringing.
• Give an update of what is happening in:
• 5G security research: Lot of research is on-going on 5G security and several projects exist on the topic.
• 5G security standards: Standardization bodies have already started working 5G security and their work progress will be reviewed. Also any gap or additional standardization requirements will be discussed.
• Verticals and business (non-technical) 5G security requirements: 5G is playground where different verticals besides the telecom industry is playing a role and their requirements will be key for the design of 5G security. In addition 5G is where "security" will become the business driver.
• Debate about hot topics such as: IoT security, Advances in lightweight cryptography, Slicing security. Privacy. Secure storage and processing. Security of the interconnection network (DIAMETER security). Relevance of Quantum Safe Cryptography for 5G, Authorization concepts....

Slides for 5G Security here.

In addition, Jaya Baloo, CISO, KPN Telecom talks about 5G network security at TechXLR8 2017. Embedded is a video of that:

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

Different types of Mobile Masts

Today's post is inspired by two things. One of them being my most popular answer on Quora. As you can see, its gathered over 19K upvotes.

@MarcAlleraEE @ee #EEGoldenSIM killinghall mast? pic.twitter.com/eadBmZoJdd

— Sheree Barker (@SHEREEBEE) June 2, 2017

The other being #EEGoldenSIM competition started by Marc Allera, CEO of UK mobile operator, EE,. The users were required to find a mast, take a picture and share it. This led to a lot of people asking how do masts look like but also generated lots of interesting pictures. You can search #EEGoldenSIM on twitter to see them.

Below is a presentation prepared by my 3G4G colleagues on how different types of antennas and mobile masts look like. Hope you like it.

Antennas: A Collection from 3G4G