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Monday, 19 June 2017

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:



Sunday, 11 June 2017

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:

Thursday, 1 June 2017

Smartphones, Internet Trends, etc

Every few years I add Mary Meeker's Internet Trends slides on the blog. Interested people can refer to 2011 and  2014 slide pack to see how world has changed.


One of the initial slide highlights that the number of smartphones are reached nearly 3 billion by end of 2016. If we looked at this excellent recent post by Tomi Ahonen, there were 3.2 billion smartphones at the end of Q1 2017. Here is a bit of extract from that.

SMARTPHONE INSTALLED BASE AT END OF MARCH 2017 BY OPERATING SYSTEM

Rank . OS Platform . . . . Units . . . . Market share  Was Q4 2016
1 . . . . All Android . . . . . . . . . . . . 2,584 M . . . 81 % . . . . . . ( 79 %)  
a . . . . . . Pure Android/Play . . . . 1,757 M . . . 55%
b . . . . . . Forked Anroid/AOSP . . . 827 M . . . 26%
2 . . . . iOS  . . . . . . . . . . . . . . . . . . 603 M . . . 19 % . . . . . . ( 19 %) 
Others . . . . . . . . . . . . . . . . . . . . . . 24 M  . . . . 1 % . . . . . . (   1 %)
TOTAL Installed Base . 3,211 M smartphones (ie 3.2 Billion) in use at end of Q1, 2017

Source: TomiAhonen Consulting Analysis 25 May 2017, based on manufacturer and industry data


BIGGEST SMARTPHONE MANUFACTURERS BY UNIT SALES IN Q1 2017

Rank . . . Manufacturer . Units . . . Market Share . Was Q4 2016 
1 (2) . . . Samsung . . . .  79.4 M . . 22.7% . . . . . . . ( 17.9% ) 
2 (1) . . . Apple  . . . . . . . 50.8 M . . 14.5% . . . . . . . ( 18.0% ) 
3 (3) . . . Huawei  . . . . . . 34.6 M . . . 9.9% . . . . . . . (10.4% ) 
4 (4) . . . Oppo . . . . . . . . 28.0 M . . . 8.0% . . . . . . . (   7.1% ) 
5 (5) . . . Vivo . . . . . . . . . 22.0 M . . . 6.3% . . . . . . . (   5.6% ) 
6 (9) . . . LG  . . . . . . . .  . 14.8 M . . . 4.2% . . . . . . . (   3.3% ) 
7 (7) . . . Lenovo .  . . . . . 13.2 M . . . 3.8% . . . . . . . (   3.8% )
8 (8) . . . Gionee . . . . . . . .9.6 M . . . 2.7% . . . . . . .  (   3.5% )
9 (6) . . . ZTE  . . . . . . . . . 9.2 M . . . 2.6% . . . . . . . (   5.2% ) 
10 (10) . TCL/Alcatel . . .  8.7 M . . . 2.5% . . . . . . . (  2.4% ) 
Others . . . . . . . . . . . . . . 80.2 MTOTAL . . . . . . . . . . . . . 350.4 M

Source: TomiAhonen Consulting Analysis 25 May 2017, based on manufacturer and industry data


This year, the number of slides have gone up to 355 and there are some interesting sections like China Internet, India Internet, Healthcare, Interactive games, etc. The presentation is embedded below and can be downloaded from slideshare



Sunday, 21 May 2017

Research on Unvoiced Speech Communications using Smartphones and Mobiles

A startup on kickstarter is touting world's first voice mask for smartphones. Having said that Hushme has been compared to Bane from Batman and Dr. Hannibal Lecter. Good detail of Hushme at Engadget here.

This is an interesting concept and has come back in the news after a long gap. Even though we are well past the point of 'Peak Telephony' because we now use text messages and OTT apps for non-urgent communications. Voice will always be around though for not only urgent communications but for things like audio/video conference calls.


Back in 2003 NTT Docomo generated a lot of news on this topic. Their research paper "Unvoiced speech recognition using EMG - mime speech recognition" was the first step in trying to find a way to speak silently while the other party can hear voice. This is probably the most quoted paper on this topic. (picture source).


NASA was working on this area around the same time. They referred to this approach as 'Subvocal Speech'. While the original intention of this approach was for astronauts suits, the intention was that it could also be available for other commercial use. Also, NASA was effectively working on limited number of words using this approach (picture source).

For both the approaches above, there isn't a lot of recent updated information. While it has been easy to recognize certain characters, it takes a lot of effort to do the whole speech. Its also a challenge to play your voice rather than a robotic voice to the other party.

To give a comparison of how big a challenge this is, look at the Youtube videos where they do an automatic captions generation. Even though you can understand what the person is speaking, its always a challenge for the machine. You can read more about the challenge here.

A lot of research in similar areas has been done is France and is available here.


Motorola has gone a step further and patented an e-Tattoo that can be emblazoned over your vocal cords to intercept subtle voice commands — perhaps even subvocal commands, or even the fully internal whisperings that fail to pluck the vocal cords when not given full cerebral approval. One might even conclude that they are not just patenting device communications from a patch of smartskin, but communications from your soul. Read more here.


Another term used for research has been 'lip reading'. While the initial approaches to lip reading was the same as other approaches of attaching sensors to facial muscles (see here), the newer approaches are looking at exploiting smartphone camera for this.

Many researchers have achieved reasonable success using cameras for lip reading (see here and here) but researchers from Google’s AI division DeepMind and the University of Oxford have used artificial intelligence to create the most accurate lip-reading software ever.
Now the challenge with smartphones for using camera for speech recognition will be high speed data connectivity and ability to see lip movement clearly. While in indoor environment this can be solved with Wi-Fi connectivity and looking at the camera, it may be a bit tricky outdoors or not looking at the camera while driving. Who knows, this may be a killer use-case for 5G.

By the way, this is not complete research in this area. If you have additional info, please help others by adding it in the comments section.

Related links:



Friday, 12 May 2017

5G – Beyond the Hype

Dan Warren, former GSMA Technology Director who created VoLTE and coined the term 'Phablet' has been busy with his new role as Head of 5G Research at Samsung R&D in UK. In a presentation delivered couple of days back at Wi-Fi Global Congress he set out a realistic vision of 5G really means.

A brief summary of the presentation in his own words below, followed by the actual presentation:
"I started with a comment I have made before – I really hate the term 5G.  It doesn’t allow us to have a proper discussion about the multiplicity of technologies that have been throw under the common umbrella of the term, and hence blurs the rationale for one why each technology is important in its own right.  What I have tried to do in these slides is talk more about the technology, then look at the 5G requirements, and consider how each technology helps or hinders the drive to meet those requirements, and then to consider what that enables in practical terms.

The session was titled ‘5G – beyond the hype’ so in the first three slides I cut straight to the technology that is being brought in to 5G.  Building from the Air Interface enhancements, then the changes in topology in the RAN and then looking at the ‘softwarisation’ on the Core Network.  This last group of technologies sets up the friction in the network between the desire to change the CapEx model of network build by placing functions in a Cloud (both C-RAN and an NFV-based Core, as well as the virtualisation of transport network functions) and the need to push functions to the network edge by employing MEC to reduce latency.  You end up with every function existing everywhere, data breaking out of the network at many different points and some really hard management issues.

On slide 5 I then look at how these technologies line up to meeting 5G requirements.  It becomes clear that the RAN innovations are all about performance enhancement, but the core changes are about enabling new business models from flexibility in topology and network slicing.  There is also a hidden part of the equation that I call out, which is that while technology enables the central five requirements to be met, they also require massive investment by the Operator.  For example you won’t reach 100% coverage if you don’t build a network that has total coverage, so you need to put base stations in all the places that they don’t exist today.

On the next slide I look at how network slicing will be sold.  There are three ways in which a network might be sliced – by SLA or topology, by enterprise customer and by MVNO.  The SLA or topology option is key to allowing the co-existence of MEC and Cloud based CN.  The enterprise or sector based option is important for operators to address large vertical industry players, but each enterprise may want a range of SLA’s for different applications and devices, so you end up with an enterprise slice being made up of sub-slices of differing SLA and topology.  Then, an MVNO may take a slice of the network, but will have it’s own enterprise customers that will take a sub-slice of the MVNO slice, which may in turn be made of sub-sub-slices of differing SLAs.  Somewhere all of this has be stitched back together, so my suggestion is that ‘Network Splicing’ will be as important as network slicing.

Slide illustrates all of this again and notes that there will also be other networks that have been sliced as well, be that 2G, 3G, 4G, WiFi, fixed, LPWA or anything else.  There is also going to be an overarching orchestration requirement both within a network and in the Enterprise customer (or more likely in System Integrator networks who take on the ‘Splicing’ role).  The red flags are showing that Orchestration is both really difficult and expensive, but the challenge for the MNO will also exist in the RAN.  The RRC will be a pinch point that has to sort out all of these device sitting in disparate network topologies with varying demands on the sliced RAN.

Then, in the next four slides I look at the business model around this.  Operators will need to deal with the realities of B2B or B2B2C business models, where they are the first B. The first ‘B’s price is the second ‘B’s cost, so the operator should expect considerable pressure on what it charges, and to be held contractually accountable for the performance of the network.  If 5G is going to claim 100% coverage, 5 9’s reliability, 50Mbps everywhere and be sold to enterprise customers on that basis, it is going to have to deliver it else there will be penalties to pay.  On the flip side to this, if all operators do meet the 5G targets, then they will become very much the same so the only true differentiation option will be on price.  With the focus on large scale B2B contracts, this has all the hallmarks of a race downwards and commoditisation of connectivity, which will also lead to disintermediation of operators from the value chain on applications.

So to conclude I pondered on what the real 5G justification is.  Maybe operators shouldn’t be promising everything, since there will be healthy competition on speed, coverage and reliability while those remain as differentiators.  Equally, it could just be that operators will fight out the consumer market share on 5G, but then that doesn’t offer any real uplift in market size, certainly not in mature developed world markets.  The one thing that is sure is that there is a lot of money to be spent getting there."



Let me know what do you think?

Sunday, 7 May 2017

10 years battery life calculation for Cellular IoT

I made an attempt to place the different cellular and non-cellular LPWA technologies together in a picture in my last post here. Someone pointed out that these pictures above, from LoRa alliance whitepaper are even better and I agree.

Most IoT technologies lists their battery life as 10 years. There is an article in Medium rightly pointing out that in Verizon's LTE-M network, IoT devices battery may not last very long.

The problem is that 10 years battery life is headline figure and in real world its sometimes not that critical. It all depends on the application. For example this Iota Pet Tracker uses Bluetooth but only claims battery life of  "weeks". I guess ztrack based on LoRa would give similar results. I have to admit that non-cellular based technologies should have longer battery life but it all depends on applications and use cases. An IoT device in the car may not have to worry too much about power consumption. Similarly a fleet tracker that may have solar power or one that is expected to last more than the fleet duration, etc.


So coming back to the power consumption. Martin Sauter in his excellent Wireless Moves blog post, provided the calculation that I am copying below with some additions:

The calculation can be found in 3GPP TR 45.820, for NB-IoT in Chapter 7.3.6.4 on ‘Energy consumption evaluation’.

The battery capacity used for the evaluation was 5 Wh. That’s about half or even only a third of the battery capacity that is in a smartphone today. So yes, that is quite a small battery indeed. The chapter also contains an assumption on how much power the device draws in different states. In the ‘idle’ state the device is in most often, power consumption is assumed to be 0.015 mW.

How long would the battery be able to power the device if it were always in the idle state? The calculation is easy and you end up with 38 years. That doesn’t include battery self-discharge and I wondered how much that would be over 10 years. According to the Varta handbook of primary lithium cells, self-discharge of a non-rechargable lithium battery is less than 1% per year. So subtract roughly 4 years from that number.

Obviously, the device is not always in idle and when transmitting the device is assumed to use 500 mW of power. Yes, with this power consumption, the battery would not last 34 years but less than 10 hours. But we are talking about NB-IoT so the device doesn’t transmit for most of the time. The study looked at different transmission patterns. If 200 bytes are sent once every 2 hours, the device would run on that 5 Wh battery for 1.7 years. If the device only transmits 50 bytes once a day the battery would last 18.1 years.

So yes, the 10 years are quite feasible for devices that collect very little data and only transmit them once or twice a day.

The conclusions from the report clearly state:

The achievable battery life for a MS using the NB-CIoT solution for Cellular IoT has been estimated as a function of reporting frequency and coupling loss. 

It is important to note that these battery life estimates are achieved with a system design that has been intentionally constrained in two key respects:

  • The NB-CIoT solution has a frequency re-use assumption that is compatible with a stand-alone deployment in a minimum system bandwidth for the entire IoT network of just 200 kHz (FDD), plus guard bands if needed.
  • The NB-CIoT solution uses a MS transmit power of only +23 dBm (200 mW), resulting in a peak current requirement that is compatible with a wider range of battery technologies, whilst still achieving the 20 dB coverage extension objective.  

The key conclusions are as follows:

  • For all coupling losses (so up to 20 dB coverage extension compared with legacy GPRS), a 10 year battery life is achievable with a reporting interval of one day for both 50 bytes and 200 bytes application payloads.
  • For a coupling loss of 144 dB (so equal to the MCL for legacy GPRS), a 10 year battery life is achievable with a two hour reporting interval for both 50 bytes and 200 bytes application payloads. 
  • For a coupling loss of 154 dB, a 10 year battery life is achievable with a 2 hour reporting interval for a 50 byte application payload. 
  • For a coupling loss of 154 dB with 200 byte application payload, or a coupling loss of 164 dB with 50 or 200 byte application payload, a 10 year battery life is not achievable for a 2 hour reporting interval. This is a consequence of the transmit energy per data bit (integrated over the number of repetitions) that is required to overcome the coupling loss and so provide an adequate SNR at the receiver. 
  • Use of an integrated PA only has a small negative impact on battery life, based on the assumption of a 5% reduction in PA efficiency compared with an external PA.

Further improvements in battery life, especially for the case of high coupling loss, could be obtained if the common assumption that the downlink PSD will not exceed that of legacy GPRS was either relaxed to allow PSD boosting, or defined more precisely to allow adaptive power allocation with frequency hopping.

I will look at the technology aspects in a future post how 3GPP made enhancements in Rel-13 to reduce power consumption in CIoT.

Also have a look this GSMA whitepaper on 3GPP LPWA lists the applications requirements that are quite handy.

Monday, 1 May 2017

Variety of 3GPP IoT technologies and Market Status - May 2017



I have seen many people wondering if so many different types of IoT technologies are needed, 3GPP or otherwise. The story behind that is that for many years 3GPP did not focus too much on creating an IoT variant of the standards. Their hope was that users will make use of LTE Cat 1 for IoT and then later on they created LTE Cat 0 (see here and here).

The problem with this approach was that the market was ripe for a solution to a different types of IoT technologies that 3GPP could not satisfy. The table below is just an indication of the different types of technologies, but there are many others not listed in here.


The most popular IoT (or M2M) technology to date is the humble 2G GSM/GPRS. Couple of weeks back Vodafone announced that it has reached a milestone of 50 million IoT connections worldwide. They are also adding roughly 1 million new connections every month. The majority of these are GSM/GPRS.

Different operators have been assessing their strategy for IoT devices. Some operators have either switched off or are planning to switch off they 2G networks. Others have a long term plan for 2G networks and would rather switch off their 3G networks to refarm the spectrum to more efficient 4G. A small chunk of 2G on the other hand would be a good option for voice & existing IoT devices with small amount of data transfer.

In fact this is one of the reasons that in Release-13 GSM is being enhanced for IoT. This new version is known as Extended Coverage – GSM – Internet of Things (EC-GSM-IoT ). According to GSMA, "It is based on eGPRS and designed as a high capacity, long range, low energy and low complexity cellular system for IoT communications. The optimisations made in EC-GSM-IoT that need to be made to existing GSM networks can be made as a software upgrade, ensuring coverage and accelerated time to-market. Battery life of up to 10 years can be supported for a wide range use cases."

The most popular of the non-3GPP IoT technologies are Sigfox and LoRa. Both these technologies have gained significant ground and many backers in the market. This, along with the gap in the market and the need for low power IoT technologies that transfer just a little amount of data and has a long battery life motivated 3GPP to create new IoT technologies that were standardised as part of Rel-13 and are being further enhanced in Rel-14. A summary of these technologies can be seen below


If you look at the first picture on the top (modified from Qualcomm's original here), you will see that these different IoT technologies, 3GPP or otherwise address different needs. No wonder many operators are using the unlicensed LPWA IoT technologies as a starting point, hoping to complement them by 3GPP technologies when ready.

Finally, looks like there is a difference in understanding of standards between Ericsson and Huawei and as a result their implementation is incompatible. Hopefully this will be sorted out soon.


Market Status:

Telefonica has publicly said that Sigfox is the best way forward for the time being. No news about any 3GPP IoT technologies.

Orange has rolled out LoRa network but has said that when NB-IoT is ready, they will switch the customers on to that.

KPN deployed LoRa throughout the Netherlands thereby making it the first country across the world with complete coverage. Haven't ruled out NB-IoT when available.

SK Telecom completed nationwide LoRa IoT network deployment in South Korea last year. It sees LTE-M and LoRa as Its 'Two Main IoT Pillars'.

Deutsche Telekom has rolled out NarrowBand-IoT (NB-IoT) Network across eight countries in Europe (Germany, the Netherlands, Greece, Poland, Hungary, Austria, Slovakia, Croatia)

Vodafone is fully committed to NB-IoT. Their network is already operational in Spain and will be launching in Ireland and Netherlands later on this year.

Telecom Italia is in process of launching NB-IoT. Water meters in Turin are already sending their readings using NB-IoT.

China Telecom, in conjunction with Shenzhen Water and Huawei launched 'World's First' Commercial NB-IoT-based Smart Water Project on World Water Day.

SoftBank is deploying LTE-M (Cat-M1) and NB-IoT networks nationwide, powered by Ericsson.

Orange Belgium plans to roll-out nationwide NB-IoT & LTE-M IoT Networks in 2017

China Mobile is committed to 3GPP based IoT technologies. It has conducted outdoor trials of NB-IoT with Huawei and ZTE and is also trialing LTE-M with Ericsson and Qualcomm.

Verizon has launched Industry’s first LTE-M Nationwide IoT Network.

AT&T will be launching LTE-M network later on this year in US as well as Mexico.

Sprint said it plans to deploy LTE Cat 1 technology in support of the Internet of Things (IoT) across its network by the end of July.

Further reading:

Thursday, 20 April 2017

5G: Architecture, QoS, gNB, Specifications - April 2017 Update


The 5G NR (New Radio) plan was finalised in March (3GPP press release) and as a result Non-StandAlone (NSA) 5G NR will be finalised by March 2018. The final 3GPP Release-15 will nevertheless include NR StandAlone (SA) mode as well.

NSA is based on Option 3 (proposed by DT). If you dont know much about this, then I suggest listening to Andy Sutton's lecture here.


3GPP TR 38.804: Technical Specification Group Radio Access Network; Study on New Radio Access Technology; Radio Interface Protocol Aspects provides the overall architecture as shown above

Compared to LTE the big differences are:

  • Core network control plane split into AMF and SMF nodes (Access and Session Management Functions). A given device is assigned a single AMF to handle mobility and AAA roles but can then have multiple SMF each dedicated to a given network slice
  • Core network user plane handled by single node UPF (User Plane Function) with support for multiple UPF serving the same device and hence we avoid need for a common SGW used in LTE. UPF nodes may be daisy chained to offer local breakout and may have parallel nodes serving the same APN to assist seamless mobility.

Hat tip Alistair Urie.
Notice that like eNodeB (eNB) in case of LTE, the new radio access network is called gNodeB (gNB). Martin Sauter points out in his excellent blog that 'g' stands for next generation.

3GPP TS 23.501: Technical Specification Group Services and System Aspects; System Architecture for the 5G System; Stage 2 provides architecture model and concepts including roaming and non-roaming architecture. I will probably have to revisit as its got so much information. The QoS table is shown above. You will notice the terms QFI (QoS Flow Identity) & 5QI (5G QoS Indicator). I have a feeling that there will be a lot of new additions, especially due to URLLC.

Finally, here are the specifications (hat tip Eiko Seidel for his excellent Linkedin posts - references below):
5G NR will use 38 series (like 25 series for 3G & 36 series for 4G).

RAN3 TR 38.801 v2.0.0 on Study on New Radio Access Technology; Radio Access Architecture and Interfaces

RAN1 TR 38.802 v2.0.0 on Study on New Radio (NR) Access Technology; Physical Layer Aspects

RAN4 TR 38.803 v2.0.0 on Study on New Radio Access Technology: RF and co-existence aspects

RAN2 TR 38.804 v1.0.0 on Study on New Radio Access Technology; Radio Interface Protocol Aspects

38.201 TS Physical layer; General description
38.211 TS Physical channels and modulation
38.212 TS Multiplexing and channel coding
38.213 TS Physical layer procedures
38.214 TS Physical layer measurements
38.21X TS Physical layer services provided to upper layer
38.300 TS Overall description; Stage-2
38.304 TS User Equipment (UE) procedures in idle mode
38.306 TS User Equipment (UE) radio access capabilities
38.321 TS Medium Access Control (MAC) protocol specification
38.322 TS Radio Link Control (RLC) protocol specification
38.323 TS Packet Data Convergence Protocol (PDCP) specification
38.331 TS Radio Resource Control (RRC); Protocol specification
37.3XX TS [TBD for new QoS]
37.3XX TS Multi-Connectivity; Overall description; Stage-2
38.401 TS Architecture description
38.410 TS NG general aspects and principles
38.411 TS NG layer 1
38.412 TS NG signalling transport
38.413 TS NG Application Protocol (NGAP)
38.414 TS NG data transport
38.420 TS Xn general aspects and principles
38.421 TS Xn layer 1
38.422 TS Xn signalling transport
38.423 TS Xn Application Protocol (XnAP)
38.424 TS Xn data transport
38.425 TS Xn interface user plane protocol
38.101 TS User Equipment (UE) radio transmission and reception
38.133 TS Requirements for support of radio resource management
38.104 TS Base Station (BS) radio transmission and reception
38.307 TS Requirements on User Equipments (UEs) supporting a release-independent frequency band
38.113 TS Base Station (BS) and repeater ElectroMagnetic Compatibility (EMC)
38.124 TS Electromagnetic compatibility (EMC) requirements for mobile terminals and ancillary equipment
38.101 TS User Equipment (UE) radio transmission and reception
38.133 TS Requirements for support of radio resource management
38.104 TS Base Station (BS) radio transmission and reception
38.141 TS Base Station (BS) conformance testing

Note that all specifications are not in place yet. Use this link to navigate 3GPP specs: http://www.3gpp.org/ftp/Specs/archive/38_series/

Further reading:



Saturday, 15 April 2017

Self-backhauling: Integrated access and backhaul links for 5G


One of the items that was proposed during the 3GPP RAN Plenary #75 held in Dubrovnik, Croatia, was Study on Integrated Access and Backhaul for NR (NR = New Radio). RP-17148 provides more details as follows:

One of the potential technologies targeted to enable future cellular network deployment scenarios and applications is the support for wireless backhaul and relay links enabling flexible and very dense deployment of NR cells without the need for densifying the transport network proportionately. 

Due to the expected larger bandwidth available for NR compared to LTE (e.g. mmWave spectrum) along with the native deployment of massive MIMO or multi-beam systems in NR creates an opportunity to develop and deploy integrated access and backhaul links. This may allow easier deployment of a dense network of self-backhauled NR cells in a more integrated manner by building upon many of the control and data channels/procedures defined for providing access to UEs. An example illustration of a network with such integrated access and backhaul links is shown in Figure 1, where relay nodes (rTRPs) can multiplex access and backhaul links in time, frequency, or space (e.g. beam-based operation).

The operation of the different links may be on the same or different frequencies (also termed ‘in-band’ and ‘out-band’ relays). While efficient support of out-band relays is important for some NR deployment scenarios, it is critically important to understand the requirements of in-band operation which imply tighter interworking with the access links operating on the same frequency to accommodate duplex constraints and avoid/mitigate interference. 

In addition, operating NR systems in mmWave spectrum presents some unique challenges including experiencing severe short-term blocking that cannot be readily mitigated by present RRC-based handover mechanisms due to the larger time-scales required for completion of the procedures compared to short-term blocking. Overcoming short-term blocking in mmWave systems may require fast L2-based switching between rTRPs, much like dynamic point selection, or modified L3-based solutions. The above described need to mitigate short-term blocking for NR operation in mmWave spectrum along with the desire for easier deployment of self-backhauled NR cells creates a need for the development of an integrated framework that allows fast switching of access and backhaul links. Over-the-air (OTA) coordination between rTRPs can also be considered to mitigate interference and support end-to-end route selection and optimization.

The benefits of integrated access and backhaul (IAB) are crucial during network rollout and the initial network growth phase. To leverage these benefits, IAB needs to be available when NR rollout occurs. Consequently, postponing IAB-related work to a later stage may have adverse impact on the timely deployment of NR access.


There is also an interesting presentation on this topic from Interdigital on the 5G Crosshaul group here. I found the following points worth noting:

  • This will create a new type of interference (access-backhaul interference) to mitigate and will require sophisticated (complex) scheduling of the channel resources (across two domains, access and backhaul).
  • One of the main drivers is Small cells densification calling for cost-effective and low latency backhauling
  • The goal would be to maximize efficiency through joint optimization/integration of access and backhaul resources
  • The existing approach of Fronthaul using CPRI will not scale for 5G, self-backhaul may be an alternative in the shape of wireless fronthaul

Let me know what you think.

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Saturday, 8 April 2017

The Iconic British Red Phone Boxes

Source: BBC

Brits love their red phone boxes. Even with mobiles prevalent today, we don't want to get rid of the phone boxes. The BBC estimates that there are 46,000 phones boxes in use today, including 8,000 red ones.

Some of these phone boxes are being put to other interesting uses too. One of them has become 'world's smallest museum', another has been converted into a coffee shop, yet another one is a salad bar and another one in Cumbria is hosting life saving medical equipment. This is all thanks to BT that has encouraged adoption of some of these much loved icons for as little as £1.



Two British Phonebox enthusiasts, Prof. Nigel Linge and Prof. Andy Sutton have written a very well researched and comprehensive book on this topic looking at the history and evolution of the humble phone boxes through all of its major models, including those that were introduced by organisations such as the emergency services. The British Phonebox is available to purchase from Amazon and other popular bookshops.


In addition to the book, they have also written an article in 'The Journal' that gives a taster of whats in the book. Its available to download here.

5 interesting facts from the little reading that I did on this topic:

  • The model K1 (K stand for Kiosk) was very unpopular and hence a competition was held to find the best possible design. The winning design by Sir Giles Gilbert Scott became K2 that was rolled out in 1926
  • Sir Giles had suggested silver colour with blue and green interior. This was changed to red for making it easy to spot
  • The latest model is called KX100+
  • The most popular and loved model is the K6 that was designed to celebrate King George V’s Silver Jubilee, though he died before any of them were actually installed.
  • Before Queen Elizabeth came along, a vague representation of the Tudor crown was used on the telephone boxes. Wanting to put her stamp on things after she ascended to the throne in 1952, QEII had all of the crowns changed to St. Edward's Crown, the crown actually used in coronations. Scotland opted to keep the Crown of Scotland on theirs, and so all K6 boxes manufactured after 1955 had to be made with a slot in the top to insert the plate with the correct crown depending on the location of the booth.

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