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

Wireless Smart Ubiquitous Network (Wi-SUN) - Another IoT Standard

While we have been discussing IoT these last few weeks, here is another one that I came across. This picture above from a recent Rethink research shows that Wi-SUN is going to enjoy more growth than LoRaWAN or Sigfox. Another recent report by Mobile Experts also makes a mention of this IoT technology.

I am sure most of the readers have not heard of Wi-SUN, so what exactly is Wi-SUN technology?

From Rethink Research, The Wi-SUN Alliance was formed in 2011 to form an organization to push adoption of the IEEE 802.15.4g standard, which aimed to improve utility networks using a narrowband wireless technology. The peer-to-peer self-healing mesh has moved from its initial grid focus to encompass smart city applications (especially street lighting), and we spoke to its Chairman, Phil Beecher, to learn more.

Beecher explained that the non-profit Alliance set about defining subsets of the open standards, testing for interoperability, and certifying compatible products, and soon developed both a Field Area Network (FAN) and a Home Area Network (HAN), which allowed it to move into Home Energy Management Systems (HEMS) in Japan – a country that is leading the curve in HEMS deployments and developments.

As can be seen in the picture above:

• Develops technical specifications of Physical Layer (PHY) and Medium Access Control (MAC) layers, with Network layer as required
• Develop Interoperability test programs to ensure implementations are interoperable
• Physical layer specification is based on IEEE802.15.4g/4u/4v
• MAC layer may use different options depending on the application
• Profile specifications are categorized based on application types

Picture source for the last three pics, Wi-SUN presentation here.

A new whitepaper from Wi-SUN Alliance provides comparison of Wi-SUN, LoRaWAN and NB-IoT.

A recent presentation by Dr. Simon Dunkley in Cambridge Wireless is embedded below:

Critical networking using mesh Wi-SUN technology from 3G4G

Further reading:

• Wi-SUN Alliance: Whitepapers
• Wi-SUN Alliance: Presentations
• Wi-SUN Alliance Advances Smart Cities, IoT In India After Completing First Interoperability Event Of IEEE802.15.4u PHY
• WiSUN: A Proven Solution Delivering Ubiquitous Connectivity
• Wi-SUN Alliance releases smart city and metering protocol standard

MNO Internet of Things (IoT) Rollouts Tracker

We have just created a (nearly) live IoT tracker for anyone interested in tracking the IoT deployments. The updated version will be available on Slideshare on a regular basis

MNO IoT Rollout Tracker from 3G4G

Further reading:

• An Introduction to IoT: Connectivity & Case Studies
• Variety of 3GPP IoT technologies and Market Status - May 2017
• New whitepaper on Narrowband Internet of Things
• 3GPP Rel-14 IoT Enhancements
• 10 years battery life calculation for Cellular IoT

Mission Critical Services update from 3GPP - June 2017

3GPP has published an overview of what has been achieved so far in the Mission Critical and also provides an outlook of what can be expected in the near future. A more detailed paper summarizing the use cases and functional aspects of Rel-13, Rel-14 and upcoming Rel-15 will be published later this year.

Mission Critical Services – Detailed List of Rel-13, Rel-14 and Rel-15 Functionalities

Rel-13 MCPTT (completed 2016)

• User authentication and service authorization
• Configuration
• Affiliation and de-affiliation
• Group calls on-network and off-network (within one system or multiple systems, pre-arranged or chat model, late entry, broadcast group calls, emergency group calls, imminent peril group calls, emergency alerts)
• Private calls on-network and off-network (automatic or manual commencement modes, emergency private calls)
• MCPTT security
• Encryption (media and control signalling)
• Simultaneous sessions for call
• Dynamic group management (group regrouping)
• Floor control in on-network (within one system or across systems) and in off-network
• Pre-established sessions
• Resource management (unicast, multicast, modification, shared priority)
• Multicast/Unicast bearer control, MBMS (Multimedia Broadcast/Multicast Service) bearers
• Location configuration, reporting and triggering
• Use of UE-to-network relays

Rel-14 MC Services (completed 2017)

MC Services Common Functionalities:

• User authentication and service authorization
• Service configuration
• Affiliation and de-affiliation
• Extended Location Features
• (Dynamic) Group Management
• Identity management
• MC Security framework
• Encryption (media and control signalling)

MCPTT Enhancements:

• First-to-answer call setup (with and without floor control)
• Floor control for audio cut-in enabled group
• Updating the selected MC Service user profile for an MC Service
• Ambient listening call
• MCPTT private call-back request
• Remote change of selected group

MCVideo, Common Functions plus:

• Group Call (including emergency group calls, imminent peril group calls, emergency alerts)
• Private Call (off-network)
• Transmission Control

MCData, Common Functions plus:

• Short Data Service (SDS)
• File Distribution (FD) (on-network)
• Transmission and Reception Control
• Handling of Disposition Notifications
• Communication Release

Rel-15 MC Services (in progress)

MC Services Common Functionalities Enhancements:

• Enhanced MCPTT group call setup procedure with MBMS bearer
• Enhanced Location management, information and triggers
• Interconnection between 3GPP defined MC systems
• Interworking with legacy systems

MCPTT Enhancements:

• Remotely initiated MCPTT call
• Enhanced handling of MCPTT Emergency Alerts
• Enhanced Broadcast group call
• Updating pre-selected MC Service user profile
• Temporary group call - user regroup
• Functional alias identity for user and equipment
• Multiple simultaneous users

MCVideo Additions:

• Video push
• Video pull
• Private call (on-network)
• Broadcast Group Call
• Ambient Viewing Call
• Capability information sharing
• Simultaneous Sessions
• Use of MBMS transmission
• Emergency and imminent peril private communications
• Primary and Partner MC system interactions for MCVideo communications
• Remote video parameters control capabilities

MCData Additions:

• MCData specific Location
• Enhanced Status
• Accessing list of deferred communications
• Usage of MBMS
• Emergency Alert
• Data streaming
• File Distribution (FD) (off-network)
• IP connectivity

Release-14 features will be available by end of September 2017 and many Release-15 features, that is being hurried due to 5G will be available by June 2018.

For more details, follow the links below:

• Mission Critical Services in 3GPP
• 3GPP TSG-SA WG6 Meeting #17 - Agenda, Documents and Reports

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