Stress Testing of LTE devices

Another interesting presentation from R&S LTE Summit 2013 embedded below:

Stressing a LTE device with Typical User Behaviors from Zahid Ghadialy

C-RAN Architecture and Challenges

I have blogged about Cloud RAN or C-RAN in the Metrocells blog here and am looking forward to more discussions on this topic in the SON conference later this year.


I came across this interesting presentation from Orange in the LTE World Summit this year where the authors have detailed the C-RAN architecture and also discussing the fronthaul challenges faced by C-RAN. The presentation is embedded as follows. Please feel free to add your comments with your opinions.

C-RAN architecture and fronthaul challenges from Zahid Ghadialy

2 Factor and 3 Factor Authentication (2FA / 3FA)

Found an interesting slide showing 2 Factor Authentication in picture from a presentation in LTE World Summit

You can also read more about this and Multi-factor Authentication (MFA) on Wikipedia here.

M2M, Cellular and Small Cells

I have written a post on this topic in the Cisco Service Provide Mobility blog here. The article is embedded as follows:

Feel free to add any comments you may have on the blog post here.

Mobile Relay Nodes (MRN) in Rel-12

Interesting article in IEEE Comms Magazine (embedded below) about the Moving Relay Node (MRN). 3GPP has done a study on a similar topic available in 3GPP TR 36.836. To make the case for the MRN they provide a reference scenario of high speed train

The TGV Eurostar in Europe is 393 m long, moves at speed reaching 300 km/h. The Shinkansen in Japan has similar characteristics, with 480 m long, 300 km/h of commercial speed. The high speed train in China is 432 m long moving at speed reaching 350 km/h.

Due to fast moving and well shield carriage, the network in high speed train scenario faces severe Doppler frequency shift and high penetration loss, reduced handover success rate and increased power consumption of UEs.

To improve the coverage of the train deployment, access devices can be mounted on the high speed train, providing a wireless backhaul connection via the eNBs along the railway by outer antenna e.g. installed on top of the train, and wireless connectivity to the UEs inside carriages by inner antenna installed inside.

MRN is a good solution but when it has to operate alongside with many other technologies can pose challenges. The IEEE article summarises it as follows:

Furthermore, new challenges regarding interference management arise due to the use of MRNs. As the distance between an MRN and the vehicular UE served by it is very short, the MRN and the vehicular UE can communicate with each other using very low power. In addition, the VPL can further help to dampen the signal of the MRN access link that propagates out from the vehicle. Thus, compared to direct transmission, the use of MRNs generates less interference from the access link, for both downlink and uplink, to UE outside the vehicles. This is appreciated in a densely deployed urban scenario where link availabilities are usually dependent on interference rather than coverage. For the backhaul link, however, the problem becomes complicated, as interference is expected both between different MRN backhaul links, and between MRN backhaul links and macro UE. The use of predictor antennas can improve CSI accuracy to enable the use of advanced interference avoidance and cancellation schemes for the backhaul links. Nevertheless, whether enhancements on the current intercell interference coordination (ICIC) framework in LTE are needed to support the use of MRNs still requires further investigation.

I have been thinking of possible use of 8x8 MIMO, this can be one possible scenario where the network may use 8x8 or even 4x4. Anyway, the complete article is embedded below:

Making LTE fit for the IoT

Another presentation from the #FWIC2013. This presentation by Vodafone covers some of the areas where the LTE standards are being tweaked for making M2M work with them without issues.

Another area is the access barring that I have blogged about before here. This will become important when we have loads of devices trying to access the network at the same time.

The presentation is embedded below and you can also listen to the audio here.

Making LTE fit for the IoT - Vodafone from Zahid Ghadialy

Big Data and Vulnerability of Cellular Systems

I am sure most of you are aware of Big Data, if not watch this video on my old post here. Moray Rumney from Agilent recently gave a talk in #FWIC on how Big Data techniques can be used to exploit the vulnerabilities in a cellular system. Though the talk focussed on GSM and 3G, it is always a good intro. The presentation embedded below:

Collecting Big Data in an Increasingly Complex Mobile World from Zahid Ghadialy

You can also listen to the audio of his presentation here.

New RRC message in Rel-11: In-device coexistence indication

I have blogged about about IDC here and here. If the eNB is interested in knowing if the device is having an interference issue it can ask the UE to send this message in the RRC Conn Reconfiguration message. The UE would send the message if it has interference issues.

Inter-frequency handover is a good solution in case the UE is experiencing interference.

From the Rel-11 whitepaper posted last week here:

To assist the base station in selecting an appropriate solution, all necessary/available assistance information for both time and frequency domain solutions is sent together in the IDC indication. The IDC assistance information contains the list of carrier frequencies suffering from on-going interference and the direction of the interference. Additionally it may also contain time domain patterns or parameters to enable appropriate DRX configuration for time domain solutions on the serving LTE carrier frequency.

Note that the network is in the control of whether or not to activate this interference avoidance mechanism. The InDeviceCoexIndication message from the UE may only be sent if a measurement object for this frequency has been established. This is the case, when the RRCConnectionReconfiguration message from the eNB contains the information element idc-Config. The existence of this message declares that an InDeviceCoexIndication message may be sent. The IDC message indicates which frequencies of which technologies are interfered and gives assistance to possible time domain solutions. These comprise DRX assistance information and a list of IDC subframes, which indicate which HARQ processes E-UTRAN is requested to abstain from using. This information describes only proposals, it is completely up to the network to do the decisions.

Connectivity in 'Connected Vehicles'

An interesting presentation from the Future of Wireless International conference about the evolution and options for connected cars and other vehicles

Connected Vehicle - Accenture from Zahid Ghadialy

3GPP Rel.11 Technology Introduction whitepaper

Another excellent summary whitepaper by R&S, embedded below:

LTE- Advanced (3GPP Rel.11) Technology Introduction from Zahid Ghadialy

Nice way of showing HetNets, by Cisco #LTEWS

This is from a presentation by Akram Awad of Cisco in the LTE World Summit 2013 in Amsterdam. I really like the way HetNets are explained

Our World Without Mobile :-)

Decision Tree of Transmission Modes (TM) for LTE

4G Americas have recently published whitepaper titled "MIMO and Smart Antennas for Mobile Broadband Systems" (available here). The above picture and the following is from that whitepaper:

Figure 3 above shows the taxonomy of antenna configurations supported in Release-10 of the LTE standard (as described in 3GPP Technical Specification TS 36.211, 36.300). The LTE standard supports 1, 2, 4 or 8 base station transmit antennas and 2, 4 or 8 receive antennas in the User Equipment (UE), designated as: 1x2, 1x4, 1x8, 2x2, 2x4, 2x8, 4x2, 4x4, 4x8, and 8x2, 8x4, and 8x8 MIMO, where the first digit is the number of antennas per sector in the transmitter and the second number is the number of antennas in the receiver. The cases where the base station transmits from a single antenna or a single dedicated beam are shown in the left of the figure. The most commonly used MIMO Transmission Mode (TM4) is in the lower right corner, Closed Loop Spatial Multiplexing (CLSM), when multiple streams can be transmitted in a channel with rank 2 or more.

Beyond the single antenna or beamforming array cases diagrammed above, the LTE standard supports Multiple Input Multiple Output (MIMO) antenna configurations as shown on the right of Figure 3. This includes Single User (SU-MIMO) protocols using either open loop or closed loop modes as well as transmit diversity and Multi-User MIMO (MU-MIMO). In the closed loop MIMO mode, the terminals provide channel feedback to the eNodeB with Channel Quality Information (CQI), Rank Indications (RI) and Precoder Matrix Indications (PMI). These mechanisms enable channel state information at the transmitter which improves the peak data rates, and is the most commonly used scheme in current deployments. However, this scheme provides the best performance only when the channel information is accurate and when there is a rich multi-path environment. Thus, closed loop MIMO is most appropriate in low mobility environments such as with fixed terminals or at pedestrian speeds.

In the case of high vehicular speeds, Open Loop MIMO may be used, but because the channel state information is not timely, the PMI is not considered reliable and is typically not used. In TDD networks, the channel is reciprocal and thus the DL channel can be more accurately known based on the uplink transmissions from the terminal (the forward link’s multipath channel signature is the same as the reverse link’s – both paths use the same frequency block). Thus, MIMO improves TDD networks under wider channel conditions than in FDD networks.

One may visualize spatial multiplexing MIMO operation as subtracting the strongest received stream from the total received signal so that the next strongest signal can be decoded and then the next strongest, somewhat like a multi-user detection scheme. However, to solve these simultaneous equations for multiple unknowns, the MIMO algorithms must have relatively large Signal to Interference plus Noise ratios (SINR), say 15 dB or better. With many users active in a base station’s coverage area, and multiple base stations contributing interference to adjacent cells, the SINR is often in the realm of a few dB. This is particularly true for frequency reuse 1 systems, where only users very close to the cell site experience SINRs high enough to benefit from spatial multiplexing SU-MIMO. Consequently, SU-MIMO works to serve the single user (or few users) very well, and is primarily used to increase the peak data rates rather than the median data rate in a network operating at full capacity.

Angle of Arrival (AoA) beamforming schemes form beams which work well when the base station is clearly above the clutter and when the angular spread of the arrival is small, corresponding to users that are well localized in the field of view of the sector; in rural areas, for example. To form a beam, one uses co-polarized antenna elements spaced rather closely together, typically lamda/2, while the spatial diversity required of MIMO requires either cross-polarized antenna columns or columns that are relatively far apart. Path diversity will couple more when the antennas columns are farther apart, often about 10 wavelengths (1.5m or 5’ at 2 GHz). That is why most 2G and 3G tower sites have two receive antennas located at far ends of the sector’s platform, as seen in the photo to the right. The signals to be transmitted are multiplied by complex-valued precoding weights from standardized codebooks to form the antenna patterns with their beam-like main lobes and their nulls that can be directed toward sources of interference. The beamforming can be created, for example, by the UE PMI feedback pointing out the preferred precoder (fixed beam) to use when operating in the closed loop MIMO mode TM4.

For more details, see the whitepaper available here.

Related posts:

• LTE-A: Downlink Transmission Mode 9 (TM-9)
• R&S Whitepaper: LTE Transmission Modes and Beamforming

What's next with 802.11!

From another brilliant presentation by R&S from their LTE Summit 2013. Last year I had a similar overview from Agilent here. This one is much more detailed on what's coming next for WiFi.

802.11: a jet plane window’s view from Zahid Ghadialy

Introduction to M2M and its developments in LTE

LTE Innovation Summit 2013 - Anandamoy Sen from Rohde & Schwarz on Vimeo.

An interesting video on Introduction to M2M and its developments in LTE from Rohde&Schwarz LTE Innovation Summit 2013.

The presentation is also embedded below and can be downloaded from Slideshare.

Introduction to M2M by Sierra Wireless from Zahid Ghadialy

Present and Future Technologies for Internet of Things (IoT)

An Interesting presentation from our Future of Wireless Conference (#FWIC2013) in Cambridge earlier this month. A question being asked is what technology will be used for Internet of Things (IoT) or Internet of Everything (IoE) as its also referred to nowadays. These 3 slides below summarises what technologies are see applicable to which scenarios.

Complete slides are embedded below and if you like to see the video, its available here.

Mapping the Future of the Internet of (Every)Thing(s) from Zahid Ghadialy

Small Cells Enhancements for 3GPP Release-12

The following presentation is by 3GPP in the not so long ago, Small Cells World Summit 2013.

Enhancements for Small Cells in 3GPP Release-12 from Zahid Ghadialy

Related Post:

• Small cell standardization in 3GPP Release 12

Adaptive Video Streaming: Principles, Improvements and Innovation

An Interdigital presentation from last year explains the principle of adaptive streaming very well for those who would not know how it worked.

This process of adaptation could be improved based on the quality of coverage at any particular time.

Interdigital are proposing a further enhancement of improving the adaptation further based on the User behaviour. If for example the user is far away then the quality need not be great on the device. On the other hand if the user is very close-by, the quality should be as good as it can get. They have explained it in a whitepaper for whoever is interested here.

A video showing this method is embedded below:

500 Billion devices by 2030, etc...

Few weeks back in the LTE World Summit 2013, I heard someone from Ericsson mention that internally they think that by 2030 there will be 500 Billion Connected devices on the planet. The population projections for 2030 is somewhere around 8.5 Billion people worldwide. As a result the figure does not come much as a surprise to me.

John Cunliffe from Ericsson is widely credited for making the statement 50 Billion connected devices by 2020. Recently he spoke in the Cambridge Wireless and defended his forecast on the connected devices. He also provided us with the traffic exploration tool to see how the devices market would look up till 2018. Here is one of the pictures using the tool:

In terms of Cellular connectivity, we are looking at 9 Billion devices by 2018. The interesting thing to notice is that in 2017, there are still some 4 Billion feature phones. While in the developed world our focus is completely on Smartphones, its interesting to see new and existing SMS/USSD based services are still popular in the developing world. Some months back I heard about Facebook developing SMS/USSD based experience for Feature phones, I am sure that would attract a lot of users from the developing world.

One thing missing from the above is non-cellular connections which will make bulk of connectivity. Wi-Fi for example is a major connectivity medium for tablets. In fact 90% of the tablets have only WiFi connectivity. Bluetooth is another popular method of connectivity. While its mostly used in conjunction with phones, it is going to be a popular way of connecting devices in the Personal Area Network's (PAN's). So its no surprise that we will see 50 Billion connected devices but maybe not by 2020. My guess would be around 2022-23.

Is it too early to talk '5G'

While LTE/LTE-A (or 4G) is being rolled out, there is already a talk about 5G. Last week in the LTE World Summit in Amsterdam, there was a whole track on what should 5G be without much technical details. Couple of months back Samsung had announced that they have reached 5G breakthrough. In my talk back in May, I had suggested that 5G would be an evolution on the Radio Access but the core will evolve just little. Anyway, its too early to speculate what the access technology for 5G would be.

Ericsson has published a '5G' whitepaper where they talk about the vision and why and what of 5G rather than going into any technical details. It is embedded below:

5G: What is it? from Ericsson

Multi-RAT mobile backhaul for Het-Nets

Recently got another opportunity to hear from Andy Sutton, Principal Network Architect, Network Strategy, EE. His earlier presentation from our Cambridge Wireless event is here. There were many interesting bits in this presentation and some of the ones I found interesting is as follows:

Interesting to see in the above that the LTE traffic in the backhaul is separated by the QCI (QoS Class Identifiers - see here) as opposed to the 2G/3G traffic.

This is EE's implementation. As you may notice 2G and 4G use SRAN (Single RAN) while 3G is separate. As I mentioned a few times, I think 3G networks will probably be switched off before the 2G networks, mainly because there are a lot more 2G M2M devices that requires little data to be sent and not consume lots of energy (which is an issue in 3G), so this architecture may be suited well.

Finally, a practical network implementation which looks different from the text book picture and the often touted 'flat' architecture. Andy did mention that they see a ping latency of 30-50ms in the LTE network as opposed to around 100ms in the UMTS networks.

Mark Gilmour was able to prove this point practically.

Here is the complete presentation:

Timing Accuracy and Phase Performance Requirements in LTE/LTE-A/4G

Nice quick summary videos from Chronos.



If you are interested in learning more on this topic or discussions, I would recommend joining the Phase Ready Linkedin group.

3 Band Carrier Aggregation in Release-12

So it looks like in the latest 3GPP RAN meeting finally more than 2 carriers have been proposed for Carrier Aggregation. The TDoclist has a few items on 3 carriers for CA. In some cases its been specified that there is 1 uplink component carrier (1UL CC) but in other cases its not specified and I have not looked into details. Its good to finally see more than 2 carriers being discussed.

Rohde&Schwarz have explained in one of their whitepapers about the numbering of CA bands.

Now there is a possibility that we may have 2 contiguous bands and 1 band from an Inter-band so the naming would be accordingly. There are also going to be new carrier types (NCT), Band 29 for example. See details here.

Finally, If you want to learn more about Carrier Aggregation (CA) or other LTE-Advanced features, my article from last year, here, would be useful.

Economical M2M using LTE - #LTEWS

In the upcoming LTE World Summit 2013 (programme here), I will be doing a briefing on the topic 'Economical M2M using LTE'. I have some ideas but I would like to hear more on what you think? In fact, is LTE the right technology from the M2M device point of view? Or do they better stick to 2G (I dont think 3G is good enough generally from low data M2M point of view). What other issues can be foreseen? Security? Roaming?

A recent presentation from Telefonica shows how they are partnering with other operators worldwide to create universal solutions. Will this help? Why not use these solutions for everything, not just LTE? LTE is data only technology isn't it?

The presentation is embedded below to draw your own conclusion but I an interested in hearing your thoughts on Twitter or here on the blog.

Telefónica - M2M Global Operator – Strategy of Alliances from Zahid Ghadialy

Five Future Technologies (#FutureTech) we may see soon in our devices!

Remember 'Internet of Everything' rather than 'Internet of Things', here is a recent Cisco video explaining this vision:

You can read more on these topics on Cisco blogs.


Next is the self-healing technology:



Spray-on clothes
These will go very well with phones where you can spray paint phone covers and maybe if its possible to dissolve the skin and re-use it, it would be an added bonus.


Just think how the technology used to design Robots can enable flexible phones and other devices.




With sensors becoming smaller and cheaper, more of them are being put in our devices. Many years back people were saying that breath analysers could be available in mobiles but I guess there wasnt a business case for that. Also many of these sensors have come as part of Bluetooth add-ons to keep the cost/weight/size of the device down. Now there is a possibility of whole new range of sensors coming to our devices.

You can read more details on this here.


Finally, there is always one user who would ask me why is there no mention of LTE in the videos above so here is a **bonus** video.

I have to mention that this didnt sound very convincing to me as a selling point. Its like back in the year 2000, 3G was being sold as an enabler to the must have 'Video calling'.

Summary of Network Security Conference (#NetworkSecurity) 2013

Summary of Network Security Conference (#NetworkSecurity) from 3G4GLtd

3GPP Public Safety focus in Rel-12

Public Safety is still a hot topic in the standards discussion and on this blog as well. Two recent posts containing presentations have been viewed and downloaded like hotcakes. See here and here.

3GPP presented on this topic in the Critical Communications World that took place last month. The following is from the 3GPP press release:

The ’Critical Communications World’ conference, held recently in Paris, has focused largely on the case for LTE standardized equipment to bring broadband access to professional users, by meeting their high demands for reliability and resilience.

Balazs Bertenyi, the 3GPP SA Chair, reported on the latest status of the first 3GPP features for public safety, in particular those covering Proximity services (Direct mode) and Group call. He spoke of the need to strike a balance between more or less customisation, to make use of commercial products while meeting the specific requirements for Public Protection and Disaster Relief (PPDR).

To ensure that these needs are met, Balazs Bertenyi called for the wholehearted participation of the critical communications community in 3GPP groups, by sending the right people to address the technical questions and obstacles that arise during the creation of work items.

A presentation and video from that event is embedded below:

LTE Standards for Public Safety – 3GPP view from Zahid Ghadialy

For more details see here.

New Carrier Type (NCT) in Release-12 and Band 29

One of the changes being worked on and is already available in Release-11 is the Band 29. Band 29 is a special FDD band which only has a downlink component and no uplink component. The intention is that this band is available an an SCell (Secondary cell) in CA (Carrier Aggregation). 

What this means is that if this is only available as an SCell, any UE that is pre-Rel-11 should not try to use this band. It should not read the system information, reference information, etc. In fact the System Information serves little or no purpose as in CA, the PCell will provide the necessary information for this SCell when adding it using the RRC Reconfiguration message. This gives rise to what 3GPP terms as New Carrier Type for LTE as defined here. An IEEE paper published not long back is embedded below that also describes this feature in detail. 

The main thing to note from the IEEE paper is what they have shown as the unnecessary information being removed to make the carrier lean.

China Mobile, in their Rel-12 workshop presentation, have suggested 3 different types/possibilities for the NCT for what they call as LTE-Hi (Hi = Hotspot and Indoor).

Ericsson, in their Rel-12 whitepaper mention the following with regards to NCT:

Network energy efficiency is to a large extent an implementation issue. However, specific features of the LTE technical specifications may improve energy efficiency. This is especially true for higher-power macro sites, where a substantial part of the energy consumption of the cell site is directly or indirectly caused by the power amplifier.

The energy consumption of the power amplifiers currently available is far from proportional to the power-amplifier output power. On the contrary, the power amplifier consumes a non-negligible amount of energy even at low output power, for example when only limited control signaling is being transmitted within an “empty” cell.

Minimizing the transmission activity of such “always-on” signals is essential, as it allows base stations to turn off transmission circuitry when there is no data to transmit. Eliminating unnecessary transmissions also reduces interference, leading to improved data rates at low to medium load in both homogeneous as well as heterogeneous deployments.

A new carrier type is considered for Release 12 to address these issues. Part of the design has already taken place within 3GPP, with transmission of cell-specific reference signals being removed in four out of five sub frames. Network energy consumption can be further improved by enhancements to idle-mode support.

The IEEE paper I mentioned above is as follows:

Everything you wanted to know on Cloud Encryption

Cloud has been in the news recently for not the right reasons. The main worry with cloud is not just where your data is located and who can have access to it but also if some rogue person or institution gets access what they will do with your data. Then there is also an issue of which third party programs are allowed to access your data and they may not be as strict in complying with the security requiremenys as the original cloud platform.

I like Dropbox (even though I am still a free user) but it is used as an example in many case studies for security related to cloud. A quick search on Google and some useful links summarising the issues with Dropbox security here, here and here.

A user on slideshare recently uploaded many presentations from the Cloud Asia 2013 in Singapore here. One of the presentations that I really liked is embedded below.

The two main things from the presentation that I really want to highlight is the Worldwide compliance which can be a bit of an issue once you want to offer your service universally and the other is the different level of encryption that is required to keep the data secure. Pictures of both as follows:

Enjoy the presentation:

Friday rant: OTT, Viber, Roaming, etc.

The same old story, mobile operators are seeing that their revenue is not growing, even though they are upgrading their networks and introducing new features / technologies. The following is from Total Telecom:

The global telecom services market generated revenue of €1.12 trillion in 2012, although at 2.7% growth was slower than in the previous year, according to the 2013 DigiWorld Yearbook published by IDATE on Thursday.

The "DigiWorld" as a whole - which also includes telecoms hardware, software and computer services, computer hardware, TV services, consumer electronics and Internet services – recorded revenues of €3.17 trillion last year, up 2.8% on 2011. By 2016 that figure will have risen to €3.66 trillion, IDATE predicts, with telecoms services contributing €1.25 trillion (see chart).

Telecoms operators are experiencing flat growth, while over-the-top (OTT) providers are seeing revenues increase by 15% a year, Vincent Bonneau, head of IDATE's Internet business unit, told attendees at the DigiWorld Yearbook launch in London earlier this month.

Another interesting piece of news was that Viber has launched a desktop application which means it can now rival Skype fully.

Guess what, I would think that operators have more to worry from this news than Skype. I have stopped using Skype for some time now due to many issues I have with it and have moved to Viber for a few months.   If you are a regular reader to this blog then you would have read my recent post complaining about the global roaming rates. When I am travelling abroad, I make sure there is WiFi and use Viber as a substitute for Voice and SMS. In fact I can send MMS and emoticons using Viber which would cost a fortune over cellular otherwise.

Sometimes it feels like the operators are sleepwalking into their own destruction by not innovating enough and fast to be a challenge for these OTT services. Not entirely sure what the solutions are but there are quite a few ideas around to start thinking in that direction. An interesting presentation by Dean Bubley I posted here is a good starting point. Another one from him and Martin Geddes is embedded below, which is quite interesting and intutive.

Enough of my rants, what do you think about this?

Internet Trends by Mary Meeker at #D11

The last time I posted the presentation by Mary Meeker was back in 2011 but the things have moved on and its amazing to see some of the things that have changed. I think the slide that summarises what I mean is as follows:

Nomophobia and FOMO are a big problem and I see this day in day out working in this industry.

The slide pack which was actually posted yesterday has already crossed 550K as I write this, in just 1 day. So you can understand how eagerly awaited event this has become every year.

To download the above, click on the Slideshare icon and then you can save from Slideshare site.

If you want to watch the video of her presentation, its available on All things digital website here.

NEC on 'Radio Access Network' (RAN) Sharing

Its been a while we looked at anything to do with Network Sharing. The last post with an embed from Dr. Kim Larsen presentation, has already crossed 11K+ views on slideshare. Over the last few years there has been a raft of announcements about various operators sharing their networks locally with the rivals to reduce their CAPEX as well as their OPEX. Even though I understand the reasons behind the network sharing I believe that the end consumers end up losing as they may not have a means of differentiating between the different operators on a macro cell.

Certain operators on the other hand offer differentiators like residential femtocells that can enhance indoor coverage or a tie up with WiFi hotspot providers which may provide them wi-fi access on the move. The following whitepaper from NEC is an interesting read to understanding how RAN sharing in the LTE would work.

“NEC’s Approach towards Active Radio Access Network Sharing” from Zahid Ghadialy

Future proofing with LTE-Advanced

Future Proofing With LTE-Advanced from Zahid Ghadialy

Is the Global Mobile Roaming model broken?

Yesterday, I noticed some heavyweights discussing roaming prices on Twitter. It is embedded below using the new Twitter embed feature:

I really don't understand why Google Maps still failsin this way twitter.com/BenedictEvans/…
— Benedict Evans (@BenedictEvans) May 18, 2013

@benedictevans it might be the Vodafone connectivity on your phone. Try O2 :)
— Carlos Domingo (@carlosdomingo) May 18, 2013

@carlosdomingo you'll have to match their roaming pricing first ;)
— Benedict Evans (@BenedictEvans) May 18, 2013

@benedictevans I am sure @ronandunneo2 will be interested in looking at it.
— Carlos Domingo (@carlosdomingo) May 18, 2013

@carlosdomingo @benedictevans ours is a fixed rate of just £1.99 a day for data and #TUGo for IP calling to anyone
— Ronan Dunne (@ronandunneo2) May 18, 2013

@ronandunneo2 @carlosdomingo not in New York, as far as I can see
— Benedict Evans (@BenedictEvans) May 18, 2013

@benedictevans @ronandunneo2 Hi Benedict, you can find our latest rates by selecting USA from the drop down list here j.mp/ML2Xzy
— O2 in the UK (@O2) May 18, 2013

@o2 @ronandunneo2 O2 in the USA: £6 per meg. Vodafone in the USA: £25 for 100 meg a day. Sorry, but that's an easy choice.
— Benedict Evans (@BenedictEvans) May 18, 2013

Those who follow me on Twitter may have noticed me ranting about the roaming prices recently so I thought that this is a perfect opportunity to put my thoughts down.

As being discussed above, I went on the websites of two UK operators and found out about their roaming rates to India and The USA and they are as follows:

 It should be noted that there is a better rate available with some kind of bundle opt-in from both the operators and I have not shown about the other UK operators but they offer a similar sort of rate so I am not trying to single out O2 and/or Vodafone.

Since LTE is 'All-IP' network my interest is more from Data point of view rather than the voice point of view. A colleague who went to India recently decided that enough is enough and he bought a SIM in India locally. Apparently is just a bit too difficult to get SIM in India if you are not an Indian resident, nevertheless he somehow managed it. The rates as shown below was INR 24 for 100 MB of data.

Rs. 24 is something like $0.50 or £0.35. You see my problem regarding the data rates? People may be quick to point out here that India has the cheapest data rates in the world. On the other hand we look at US, the rates are as follows:

Even if we assume $15 / 1GB data, its far cheaper than the roaming rate which may be something like,  £3/MB = £3000/GB or £6/MB = £6000/GB.

I blogged about all the interesting developments that have been happening in LTE World Summit regarding the roaming solutions but what is the point of having all these solutions if the operators cant work out a way to reduce these costs. Or is it that they do not want to reduce these costs as they are a good source of income?

The operators complain that the OTT services are taking business away from them and turning them into dumb data pipes but to a lot of extent its their fault. People like me who travel often dont want to spend loads of cash on data and have worked out a way around it. Most of the places I visit have WiFi, most of my work is not urgent enough and I can wait till I am in a WiFi coverage area. In some parts of the world, still I have to buy an expensive WiFi access but compared to the roaming rates, its still cheap so I have stopped complaining about it. My decision to book a hotel depends of reviews, free breakfast and free WiFi. Some of our clients who give us their phone to use abroad strictly inform us that data should not be turned on unless its a matter of life and death.

If the operators dont change their strategies and work out a better solution for the roaming rates I am afraid that their short term gains will only lead to long term pains.

Do you have an opinion? I am interested in hearing.

Access Class Barring in LTE using System Information Block Type 2

As per 3GPP TS 22.011 (Service accessibility):

All UEs are members of one out of ten randomly allocated mobile populations, defined as Access Classes (AC) 0 to 9. The population number is stored in the SIM/USIM. In addition, UEs may be members of one or more out of 5 special categories (Access Classes 11 to 15), also held in the SIM/USIM. These are allocated to specific high priority users as follows. (The enumeration is not meant as a priority sequence):
Class 15 - PLMN Staff;
 -"-  14 - Emergency Services;
 -"-  13 - Public Utilities (e.g. water/gas suppliers);
 -"-  12 - Security Services;
 -"-  11 - For PLMN Use.

Now, in case of an overload situation like emergency or congestion, the network may want to reduce the access overload in the cell. To reduce the access from the UE, the network modifies the SIB2 (SystemInformationBlockType2) that contains access barring related parameters as shown below:

For regular users with AC 0 – 9, their access is controlled by ac-BarringFactor and ac-BarringTime. The UE generates a random number
– “Rand” generated by the UE has to pass the “persistent” test in order for the UE to access. By setting ac-BarringFactor to a lower value, the access from regular user is restricted (UE must generate a “rand” that is lower than the threshold in order to access) while priority users with AC 11 – 15 can access without any restriction

For users initiating emergency calls (AC 10) their access is controlled by ac-BarringForEmergency – boolean value: barring or not

For UEs with AC 11- 15, their access is controlled by ac-BarringForSpecialAC - boolean value: barring or not.

The network (E-UTRAN) shall be able to support access control based on the type of access attempt (i.e. mobile originating data or mobile originating signalling), in which indications to the UEs are broadcasted to guide the behaviour of UE. E-UTRAN shall be able to form combinations of access control based on the type of access attempt e.g. mobile originating and mobile terminating, mobile originating, or location registration.  The ‘mean duration of access control’ and the barring rate are broadcasted for each type of access attempt (i.e. mobile originating data or mobile originating signalling).

Another type of Access Control is the Service Specific Access Control (SSAC) that we have seen here before. SSAC is used to apply independent access control for telephony services (MMTEL) for mobile originating session requests from idle-mode.

Access control for CSFB provides a mechanism to prohibit UEs to access E-UTRAN to perform CSFB. It minimizes service availability degradation (i.e. radio resource shortage, congestion of fallback network) caused by mass simultaneous mobile originating requests for CSFB and increases the availability of the E-UTRAN resources for UEs accessing other services.  When an operator determines that it is appropriate to apply access control for CSFB, the network may broadcast necessary information to provide access control for CSFB for each class to UEs in a specific area. The network shall be able to separately apply access control for CSFB, SSAC and enhanced Access control on E-UTRAN.

Finally, we have the Extended Access Barring (EAB) that I have already described here before.

Around the World with Mobile Global Insights - via @TomiAhonen

Next month we will reach the milestone where the number of active Mobile devices is equal to the number of people in the world. There are many people with more than one active mobile device and there are others who have no devices so the number of active devices will still keep rising for some time to come.

Embedded below is a presentation by Tomi Ahonen in MMAF 2013, you can see all the presentations from the event on Slideshare here.

eMBMS Physical layer aspects from T&M point of view

Based on the success of the recent posts on eMBMS, here and here, this final post on this topic is a look at physical layer perspective from Test and Measurement point of view. Slides kindly provided by R&S

eMBMS: Broadcast and Multicast in LTE from Zahid Ghadialy

A video of this is also available on Youtube, embedded below: