Different flavours of SRVCC (Single Radio Voice Call Continuity)

Single Radio Voice Call Continuity (SRVCC) has been quietly evolving with the different 3GPP releases. Here is a quick summary of these different flavors

In its simplest form, SRVCC comes into picture when an IMS based VoLTE call is handed over to the existing 2G/3G network as a normal CS call. SRVCC is particularly important when LTE is rolled out in small islands and the operator decided to provide VoLTE based call when in LTE. An alternative (used widely in practice) is to use CS Fallback (CSFB) as the voice option until LTE is rolled out in a wider area. The main problem with CSFB is that the data rates would drop to the 2G/3G rates when the UE falls back to the 2G/3G network during the voice call.

The book "LTE-Advanced: A Practical Systems Approach to Understanding 3GPP LTE Releases 10 and 11 Radio Access Technologies" by Sassan Ahmadi has some detailed information on SRVCC, the following is an edited version from the book:

SRVCC is built on the IMS centralized services (ICS) framework for delivering voice and messaging services to the users regardless of the type of network to which they are attached, and for maintaining service continuity for moving terminals.

To support GSM and UMTS, some modifications in the MSC server are required. When the E-UTRAN selects a target cell for SRVCC handover, it needs to indicate to the MME that this handover procedure requires SRVCC. Upon receiving the handover request, the MME triggers the SRVCC procedure with the MSC server. The MSC then initiates the session transfer procedure to IMS and coordinates it with the circuit-switched handover procedure to the target cell.

Handling of any non-voice packet-switched bearer is by the packet-switched bearer splitting function in the MME. The handover of non-voice packet-switched bearers, if performed, is according to a regular inter-RAT packet-switched handover procedure.

When SRVCC is enacted, the downlink flow of voice packets is switched toward the target circuit-switched network. The call is moved from the packet-switched to the circuit-switched domain, and the UE switches from VoIP to circuit-switched voice.

3GPP Rel-10 architecture has been recommended by GSMA for SRVCC because it reduces both voice interruption time during handover and the dropped call rate compared to earlier configurations. The network controls and moves the UE from E-UTRAN to UTRAN/GERAN as the user moves out of the LTE network coverage area. The SRVCC handover mechanism is entirely network-controlled and calls remain under the control of the IMS core network, which maintains access to subscribed services implemented in the IMS service engine throughout the handover process. 3GPP Rel-10 configuration includes all components needed to manage the time-critical signaling between the user’s device and the network, and between network elements within the serving network, including visited networks during roaming. As a result, signaling follows the shortest possible path and is as robust as possible, minimizing voice interruption time caused by switching from the packet-switched core network to the circuit-switched core network, whether the UE is in its home network or roaming. With the industry aligned around the 3GPP standard and GSMA recommendations, SRVCC-enabled user devices and networks will be interoperable, ensuring that solutions work in many scenarios of interest.

Along with the introduction of the LTE radio access network, 3GPP also standardized SRVCC in Rel-8 specifications to provide seamless service continuity when a UE performs a handover from the E-UTRAN to UTRAN/GERAN. With SRVCC, calls are anchored in the IMS network while the UE is capable of transmitting/ receiving on only one of those access networks at a given time, where a call anchored in the IMS core can continue in UMTS/GSM networks and outside of the LTE coverage area. Since its introduction in Rel-8, the SRVCC has evolved with each new release, a brief summary of SRVCC capability and enhancements are noted below

3GPP Rel-8: Introduces SRVCC for voice calls that are anchored in the IMS core network from E-UTRAN to CDMA2000 and from E-UTRAN/UTRAN (HSPA) to UTRAN/GERAN circuit-switched. To support this functionality, 3GPP introduced new protocol interface and procedures between MME and MSC for SRVCC from E-UTRAN to UTRAN/GERAN, between SGSN and MSC for SRVCC from UTRAN (HSPA) to UTRAN/GERAN, and between the MME and a 3GPP2-defined interworking function for SRVCC from E-UTRAN to CDMA 2000.

• 3GPP Rel-9: Introduces the SRVCC support for emergency calls that are anchored in the IMS core network. IMS emergency calls, placed via LTE access, need to continue when SRVCC handover occurs from the LTE network to GSM/UMTS/CDMA2000 networks. This evolution resolves a key regulatory exception. This enhancement supports IMS emergency call continuity from E-UTRAN to CDMA2000 and from E-UTRAN/UTRAN (HSPA) to UTRAN/ GERAN circuit-switched network. Functional and interface evolution of EPS entities were needed to support IMS emergency calls with SRVCC.

• 3GPP Rel-10: Introduces procedures of enhanced SRVCC including support of mid-call feature during SRVCC handover (eSRVCC); support of SRVCC packet-switched to circuit-switched transfer of a call in alerting phase (aSRVCC); MSC server-assisted mid-call feature enables packet-switched/ circuit-switched access transfer for the UEs not using IMS centralized service capabilities, while preserving the provision of mid-call services (inactive sessions or sessions using the conference service). The SRVCC in alerting phase feature adds the ability to perform access transfer of media of an instant message session in packet-switched to circuit-switched direction in alerting phase for access transfers.

• 3GPP Rel-11: Introduces two new capabilities: single radio video call continuity for 3G-circuit-switched network (vSRVCC); and SRVCC from UTRAN/GERAN to E-UTRAN/HSPA (rSRVCC). The vSRVCC feature provides support of video call handover from E-UTRAN to UTRAN-circuitswitched network for service continuity when the video call is anchored in IMS and the UE is capable of transmitting/receiving on only one of those access networks at a given time. Service continuity from UTRAN/GERAN circuitswitched access to E-UTRAN/HSPA was not specified in 3GPP Rel-8/9/10. To overcome this drawback, 3GPP Rel-11 provided support of voice call continuity from UTRAN/GERAN to E-UTRAN/HSPA. To enable video call transfer from E-UTRAN to UTRAN-circuit-switched network, IMS/EPC is evolved to pass relevant information to the EPC side and S5/S11/Sv/Gx/Gxx interfaces are enhanced for video bearer-related information transfer. To support SRVCC from GERAN to E-UTRAN/HSPA, GERAN specifications are evolved to enable a mobile station and base station sub-system to support seamless service continuity when a mobile station hands over from GERAN circuit-switched access to EUTRAN/ HSPA for a voice call. To support SRVCC from UTRAN to EUTRAN/ HSPA, UTRAN specifications are evolved to enable the RNC to perform rSRVCC handover and to provide relative UE capability information to the RNC.

NTT Docomo has a presentation on SRVCC and eSRVCC which is embedded below:

Improvement of VoLTE Domain HO with Operators Vision from Zahid Ghadialy

3GPP Rel-12 and Future Security Work

Here is the 3GPP presentation from the 9th ETSI Security workshop. Quite a few bits on IMS and IMS Services and also good to see new Authentication algorithm TUAK as an alternative to the widely used Milenage algorithm.

3GPP Rel-12 Security, and Future 3GPP Security Work from Zahid Ghadialy

My observations on Mobiles and OTT Apps in India

What a change 2 years can make. The last time I was in India, people were reluctant to use data, smartphones were far and few and even those smartphones were just status symbols rather than for actual 'smart' use.

This time a lot of things were very different. I found that there was a Phablet craze going on. No sooner were people starting to get used to these big screen devices they realised how many things they could do. The well to do were buying Samsung devices and the people who did not want to spend big bucks were content with the little known brands.

The Domo phablet on the left in the picture above costs around ₹8000 (£80/$130) and the Maxx on the right is roughly ₹5500 (£55/$90). Both these come with 1 year warranty.

There were also quite a few ads using celebrities promoting Phablets. Its good to see people spending on these devices. Unlike UK where most of these devices are subsidised on a contract, people in India prefer pre-paid option and buying the phone outright.

I have to admit that even though I am a fan of these big screen devices, I find the Samsung Galaxy Tab just a bit too big for the use as a phone (see pic above).

It was also good to see that people have embraced the 3G data usage as well. I got a 6GB package for roughly ₹1000 (£10/$16). I found that people complained about the speeds and were prepared to pay more for 4G (faster data rates). I also noticed that a few people were not aware of Wi-Fi and the fixed broadband. I was told that the fixed broadband was capped, offered similar prices and could be quite unreliable. I guess Wireless is helping in India where the fixed Infrastructure may still be an issue in many places.

I have to mention here that I did not meet anyone who was using an iPhone. This could be due to iPhone being ridiculously expensive and people may be thinking why pay a high price for such a small screen. A comparison of iPhone prices worldwide showed that the price of iPhone 5S as % of GDP per capita (PPP) is the highest in India. See here.


Another area of observation was SMS and OTT apps. I remember spending a lot of time trying to convince people to use OTT apps for messaging as it would be cheaper for International messages. Well, now it seems everyone has adopted it whole heartedly. One of the problems with SMS in India is that you get too much Spam SMS and sometimes the operators are the culprits. There is no way to send a stop for these SMS messages. With OTT Apps, you know who is sending you messages and you can block the offenders.

There are many OTT Apps which are popular like Hike, Line, WeChat, WhatsApp, etc. The winner though is undoubtedly WhatsApp. I met an acquaintance whose has stopped using emails for business and now relies completely on WhatsApp. Then there were others who loved it because of Group chat facility.

There were many reasons why WhatsApp is a winner. Along with a simple interface and Group chat facility, one of the other reasons pointed out was that the facility to see when the person was last online was very useful. Recently WhatsApp introduced facility to send Voice messages. This helped it acquire some of the WeChat users.

It was good to see the beginnings of the mobile revolution in India. Wonder what my next trip will show me.

Please note that this article is based on what I observed in Mumbai among friends and family. In no way should this be treated as  detailed research.

LTE-Broadcast (eMBMS) may fail again

I recently wrote a blog post for the Cisco SP Mobility blog on why the Cellular Broadcast may fail again (complete article embedded below). My main point is that small screen devices are not really suitable for mobile TV kind of applications. The larger devices like tablets are but since they do not contain the (U)SIM card, its not possible for them to receive cellular broadcast signals.

Anyway, I came across this picture below from the recent Ericsson Mobility report:

This highlights my point that more people are now preferring to watch videos over the tablets as compared to the smaller smartphone screens. Even though the other diagrams in the article does show a significant amount of users using their smartphones for viewing movies and long clips, my belief is that this will reduce over the time as the tablet share increases

A recent Business Insider article says that "One In Every 5 People In The World Own A Smartphone, One In Every 17 Own A Tablet". Once the users move to using bigger screens, their preferences on how they watch videos will definitely change.

A real interesting chart would be to show users viewing habits based on the screen size. Phablets are generally classified as smartphones but can be substitutes for tablets in many scenarios. They could definitely help the Mobile TV viewing habits on the smartphones.

Anyway, here is the complete article:

2014 Mobile Internet Prediction Survey

Interesting presentation by Chetan Sharma listing what we can expect in 2014. Slide 9 as shown in the picture above highlights the breakthrough categories. Good to see that LTE-B ('B' for broadcast) has not made it into this list. My guess is that connected cars and wearable computing will be in the news constantly throughout the year.

The complete presentation as follows:

The futuristic concept of 'Smart Batteries'

I did a presentation in the Cambridge Wireless Future technology SIG about what we call 'Smart Batteries'. The presentation is self-explanatory and is embedded below. I would be interested in hearing your thoughts about this idea.

Smart Batteries from eXplanoTech

Other links if you want to dig further on batteries:

• Li-Ion vs Li-Poly, plus how do Lithium batteries work anyway?
• Lithium-ion Batteries - Apple
• Battle of the smartphone batteries - Daily Mail
• New battery alternative emerges for hybrid cars
• Technology companies charge towards next generation battery future
• Light-weight body parts will be the battery of future cars
• These transparent solar cells provide 50% more battery life for your phone — and ‘infinite’ standby time
• Smartphone battery life: 2 problems, 4 fixes (Smartphones Unlocked)
• New lithium-ion battery design that’s 2,000 times more powerful, recharges 1,000 times faster
• The Power Treadmill

Top 15 blog posts from 2013

Here is a list of most popular blog posts from 2013. In descending order:

1. VoLTE Bearers
2. C-RAN Architecture and Challenges
3. What is WebRTC and where does it fit with LTE and IMS
4. 5G: Your Questions Answered
5. LTE-A: Downlink Transmission Mode 9 (TM-9)
6. 3GPP Rel.11 Technology Introduction whitepaper
7. New Carrier Type (NCT) in Release-12 and Band 29
8. Key challenges with automatic Wi-Fi / Cellular handover
9. The Relentless Rise of Mobile Technology
10. Access Class Barring in LTE using System Information Block Type 2
11. LTE-B, LTE-C, ... , LTE-X
12. China Mobile: A peek at 5G
13. Summary of Network Security Conference (#NetworkSecurity) 2013
14. Quick summary on LTE and UMTS / HSPA Release-12 evolution by 3GPP
15. Introduction to M2M and its developments in LTE

Advancements in Congestion control technology for M2M

NTT Docomo recently published a new article (embedded below) on congestion control approaches for M2M. In their own words:

Since 3GPP Release 10 (Rel. 10) in 2010, there has been active study of technical specifications to develop M2M communications further, and NTT DOCOMO has been contributing proactively to creating these technical specifications. In this article, we describe two of the most significant functions standardized between 3GPP Rel. 10 and Rel. 11: the M2M Core network communications infrastructure, which enables M2M service operators to introduce solutions more easily, and congestion handling technologies, which improve reliability on networks accommodating a large number of terminals.

Complete article as follows:

Core Network Infrastructure and Congestion Control Technology for M2M Communications from Zahid Ghadialy

Other related posts:

• Rise of the "Thing"
• Access Class Barring in LTE using System Information Block Type 2
• Extended Access Barring (EAB) in Release 11 to avoid MTC overload
• RAN mechanisms to avoid CN overload due to MTC
• Service Specific Access Control (SSAC) in 3GPP Release 9

Rise of the "Thing"

Light Reading carried an interesting cartoon on how M2M works. I wouldnt be surprised if some of the M2M applications at present do work like this. Jokes apart, last week the UK operator EE did a very interesting presentation on Scaling the network for the Rise of the Thing.

A question often asked is "What is the difference between the 'Internet of Things' (IoT) and 'Machine to Machine' (M2M)?". This can generate big discussions and can be a lecture on its own. Quora has a discussion on the same topic here. The picture above from the EE presentation is a good way of showing that M2M is a subset of IoT. 

Its also interesting to note how these 'things' will affect the signalling. I often come across people who tell me that since most M2M devices just use small amounts of data transfer, why is there a need to move from GPRS to LTE. The 2G and 3G networks were designed primarily for Voice with Data secondary function. These networks may work well now but what happens when the predicted 50 Billion connected devices are here by 2020 (or 500 Billion by 2030). The current networks would drown in the control signalling that would often result in congested networks. Congestion control is just one of the things 3GPP is working on for M2M type devices as blogged earlier here. In fact the Qualcomm presentation blogged about before does a decent job of comparing various technologies for IoT, see here.

The EE presentation is embedded as follows:

Scaling the Network - Rise of the Thing from Zahid Ghadialy

Another good example website I was recently made aware of is http://postscapes.com/internet-of-things-examples/ - worth checking how IoT would help us in the future.

Quick summary on LTE and UMTS / HSPA Release-12 evolution by 3GPP

A quick summary from 3GPP about the Release-12 progress (Jun. 2014 release planned) from the recent ETSI Future Mobile Summit. Presentation and video embedded below

ETSI Summit on Future Mobile and Standards for 5G

Edited from the original in 3GPP News:

The ETSI Future Mobile Summit has heard how the mobile internet will evolve over the next ten to fifteen years, and how 3GPP systems will ensure future stability as the network copes with an explosive growth in complexity and usage.

With 3GPP providing the evolutionary framework for mobility, via its Releases of new functionality and features, the more radical thinking, at the Summit, came in the form of Research projects and some future focused industry initiatives, such as the WWRF, the METIS Project and the DVB Project.

In his keynote address, Mario Campolargo - of the European Commission - introduced a new initiative on research & innovation that will provide momentum to funded work on research. The 5G Public Private Partnership is being launched as a blueprint for the deployment of 5G, in the years after 2020. 

In summing up the Summit’s main themes, the ETSI CTO, Adrian Scrase identified some certainties; “...traffic will continue to increase, connected devices will increase dramatically over time, new device types will significantly contribute to that increase (e.g., probes, sensors, meters, machines etc) and new sectors will bring new priorities (e.g, critical infrastructures).”

On the concept of 5G, Mr. Scrase reported that ultra-reliable 5G networks should, among other things, enable the tactile internet, the perception of infinite capacity and bring in augmented reality.

ETSI Future Mobile Summit: Key Messages from Zahid Ghadialy

Download the presentations:

5G, the way forward! Mario Campolargo, Director, Net Futures, DG Connect, European Commission	A new initiative 5GPPP, to accelerate and structure research & innovation."...Industry to co-create the "vision" and build global convergence by end 2015.
Who needs 5G? Hans D. Schotten, University of Kaiserslautern	Long Term Evolution of LTE (linear evolution) or Something new (5G)?
Why 5G? Rahim Tafazolli, Director of CCSR and 5GIC, The university of Surrey	Perceived infinite capacity, a new communication paradigm for 5G and Beyond
The 5G mobile and wireless communications system  Afif Osseiran, Project Coordinator of METIS	Explanation of 5G scenarios (selected) and examples of 5G technology components
Next generation wireless for a cognitive & energy-efficient future Nigel Jefferies, Wireless World Research Forum Chairman	"New technology challenges: huge number of nodes, latency , energy efficiency, backhaul and over the air signaling design...May require a whole new approach to: physical layer, air interface and spectrum usage, resources management & optimization..."
3GPP Radio Access Network : Rel-12 and beyond Dino Flore, 3GPP RAN Chairman	3GPP RAN has started a new innovation cycle which will be shaping next generation cellular systems
Spectrum for 5G, a big deal? Jens Zander, KTH, Royal Institute of Technology	A World Divided - The coverage world versus the capacity world
Opportunities for TV services over future mobile networks Nick Wells, Chairman Technical Module, DVB	Can broadcasters and mobile industry cooperate to define a new worldwide standard that will benefit both broadcasters and mobile industry?
3GPP core network & services evolution Atle Monrad, 3GPP CT Chairman	Architecture evolution, More new nodes, CS-domain removal?, new ways of design of networks?
The impact of NFV on future mobile Uwe Janssen, Deutsche Telekom, lead delegate to Network Functions Virtualisation ISG	The challenge for Operators, Suppliers and Standards Bodies
The tactile internet - Driving 5G Gerhard Fettweis, Technical University of Dresden	3D Chip-Stacks & High-Rate Inter-Chip Communications, Monitoring / Sensing, Tactile internet - Latency Goals
Summit conclusions Adrian Scrase, ETSI CTO, Head of 3GPP MCC	Includes the 'Standardization Challenges' raised by the Summit.

Bandwidth is not the answer – it’s stationarity

Martin Geddes did an interesting presentation in Future of Broadband workshop. The ITU has the following write-up on that workshop

Eye-opening, evangelical and extremely well attended: this afternoon’s Future of Broadband workshop was all about exploding established concepts on how telcos should go about improving both customer experience and their bottom line.

Ranking broadband in terms of speed is the standard approach, but speed is not the only thing that matters in this business, according to Martin Geddes of Geddes Consulting, running the workshop in conjunction with Neill Davies of Predictable Network Solutions.  He illustrated his point with a series of examples drawn from customers accessing broadband at different speeds – but with unexpectedly different experiences.

Slower broadband, whether over cable, satellite or fibre, in many cases offered a better quality of customer experience than the faster variant. Why? Variability, or rather lack of variability, is the key. A stable service, even it is slower, enables POTS-quality VoiP, whereas a highly-variable, faster service delivers a less satisfactory customer experience – and, by definition, an unhappier customer.

“The hidden secret of networking is that the network delivers loss and delay between packets,” said Geddes, “There is more to broadband than speed or capacity: with many customers wanting lots of different things at once, we also need an absence of variability, and that is what we call stationarity.”

Looked at from the network operator side, there are two key areas to consider: what is driving the cost of broadband and pushing capex sky high, and how to retain and increase your customer base to bring in the revenue. The answers, it seems, are not immediately obvious.

To start with, the knee-jerk telco reaction of pouring capex into infrastructure upgrades and increased capacity is simply not the way to ensure good quality of service and happy customers.  Demand for broadband is highly elastic, expanding to consume whatever supply is on offer and creating a “jack-hammer effect” – which produces variability. Paradoxically, increased investment in bandwidth may be behind that very poor service which leads to customer churn and the panicked assumption that another upgrade is necessary – an “investment cycle of doom.”

This is a deep systemic problem in the industry investment machine. Rushing to premature upgrades masks the real core issue, that of quality of service.  The presenters demonstrated this in heaven-hell model, where full network capacity and happy customers is telco heaven – and the converse, unhappy customers and underused network, is of course telco hell.  Getting the balance is not easy, as increasing local networks pushes down the quality of experience for applications with strong stationarity requirements – exactly what the customer is after.

For Martin, there is a tiny root cause of this: all current packet-based infrastructure relies on it being idle and keeping queues empty to ensure good quality. So your assets must stay idle to keep your customer. The solution lies in thinking about how to reframe both this problem, and the exact nature of the resource the operators are selling.

“Don’t make packets move for their own sake, but focus on customer experience. Change the resource model,” urged Martin. “Throw away the bandwidth model and thought process.” Efficiently allocating resources to customers is more important than bandwidth. Increase capacity, but only in a very targeted way.  In other words, meet heterogeneous  demand with a differentiated product.

This, then, is how to ensure a future of broadband heaven: understand that quality of experience is a function of loss and delay. Characterize your supply requirements properly. Work out what customers are after, certifying fitness of purpose for a particular, actual customer demand rather than a generalised one-size-fits-all concept. And, in the words of the workshop presenters: “Don’t sell bandwidth – sell differential experiences.”

His presentation is embedded as follows:

SON Periodical table

Came across this in a presentation from the SON Conference back in Oct. 2013.

Agile IMS for the All-IP Era

Presentation by Oracle in the LTE Asia Summit 2013

Agile IMS for the All-IP Era from Zahid Ghadialy

Mobile Video Offload using Wi-Fi is the only solution in the coming years

A very interesting infographic from Skyfire some months back highlighted some very valid issues about Video on mobiles.

Personally, I do watch quite a bit of video on my phone and tablet but only when connected using Wi-Fi. Occasionally when I am out, if someone sends me video clip on Whatsapp or some link to watch Video on youtube, I do try and see it. Most of the time the quality is too disappointing. It could be because my operator has been rated as the worst operator in UK. Anyway, as the infographic above suggests, there needs to be some kind of an optimisation done to make sure that end users are happy. OR, the users cn offload to Wi-Fi when possible to get a better experience.

This is one of the main reasons why operators are actively considering offloading to Wi-Fi and have carrier WiFi solutions in place. The standards are actively working in the same direction. Two of my recent posts on the topic of 'roaming using ANDSF' and 'challenges with seamless cellular/Wi-Fi handover' have been quite popular.

Recently I attended a webinar on the topic of 'Video Offload'. While the webinar reinforced my beliefs about why offload should be done, it did teach me a thing or two (like when is a Hotspot called a Homespot - see here). The presentation and the Video is embedded below. Before that, I want to show the result of a poll conducted during the webinar where the people present (and I would imagine there were quite a few people) were asked about how they think MNO will approach the WiFi solution in their network. Result as follows:

Here is the presentation:

Video Offload -Six trends you NEED to understand! from Zahid Ghadialy

Here is the video of the event:

SIPTO Evolution

Couple of years back I did a post on SIPTO (Selected IP Traffic Offload) and related technologies coming as part of Rel-10. I also put up a comparison for SIPTO, LIPA and IFOM here. Having left it for couple of years, I found that there have been some enhancements to the architecture from the basic one described here.

I have embedded the NEC paper below for someone wanting to investigate further the different options shown in the picture above. I think that even though the operator may offload certain type of traffic locally, they would still consider that data as part of the bundle and would like to charge for it. At the same time there would be a requirement on the operator for lawful interception, so not sure how this will be managed for different architectures. Anyway, feel free to leave comments if you have any additional info.

NEC: Mobile Traffic Offload from Zahid Ghadialy

The Relentless Rise of Mobile Technology

Mobiles have been rising and rising. Couple of weeks back I read 'Mobile is considered the first and most important screen by nearly half of the 18- to 34-year-old demographic, according to research commissioned by Weve.'

The finding placed mobile ahead of laptops or PCs (chosen by 30.6 per cent) and way ahead of TV (12.4 per cent) as the first and most important screen in the lives of people between the ages of 18 and 34. 

Just 5.8 per cent of those surveyed in the age group chose a tablet as their "first screen".
The research also found that 45 per cent of 18- to 34-year-olds consider their mobile their first choice of device when interacting with online content, placing the platform just ahead of laptops and PCs, which scored 43 per cent. 

Among the wider 18 to 55 age group surveyed, a PC or laptop was seen as the "first screen" with 39.8 per cent naming either computer as their most important screen, while smartphones came second on 28 per cent. 

TV was in third place with 27 per cent of people naming it as their most important screen. Five per cent of the total group said they considered a tablet their "first screen". 

Only a quarter of the 18 to 55 age group said mobile would be their first choice platform if they wanted to access the internet, while nearly two thirds preferred to use a PC or laptop.

Tomi Ahonen has always been referring to Mobile as the 7th Mass Media.

So when I saw this above picture (and there are more of them) in Ben Evaans slide deck (embedded below), it just reiterated my belief that Mobile will take over the world sooner or later. Anyway, the slides are interesting to go through.

Key challenges with automatic Wi-Fi / Cellular handover

Recently in a conference I mentioned that the 3GPP standards are working on standards that will allow automatic and seamless handovers between Cellular and Wi-Fi. At the same time operators may want to have a control where they can automatically switch on a users Wi-Fi radio (if switched off) and offload to Wi-Fi whenever possible. It upset quite a few people who were reasoning against the problems this could cause and the issues that need to be solved.

I have been meaning to list the possible issues which could be present in this scenario of automatically handing over between Wi-Fi and cellular, luckily I found that they have been listed very well in the recent 4G Americas whitepaper. The whitepaper is embedded below but here are the issues I had been wanting to discuss:

In particular, many of the challenges facing Wi-Fi/Cellular integration have to do with realizing a complete intelligent network selection solution that allows operators to steer traffic in a manner that maximizes user experience and addresses some of the challenges at the boundaries between RATs (2G, 3G, LTE and Wi-Fi).
Figure 1 (see above) below illustrates four of the key challenges at the Wi-Fi/Cellular boundary.
1) Premature Wi-Fi Selection: As devices with Wi-Fi enabled move into Wi-Fi coverage, they reselect to Wi-Fi without comparative evaluation of existing cellular and incoming Wi-Fi capabilities. This can result in degradation of end user experience due to premature reselection to Wi-Fi. Real time throughput based traffic steering can be used to mitigate this.
2) Unhealthy choices: In a mixed wireless network of LTE, HSPA and Wi-Fi, reselection may occur to a strong Wi-Fi network, which is under heavy load. The resulting ‘unhealthy’ choice results in a degradation of end user experience as performance on the cell edge of a lightly loaded cellular network may be superior to performance close to a heavily loaded Wi-Fi AP. Real time load based traffic steering can be used to mitigate this.
3) Lower capabilities: In some cases, reselection to a strong Wi-Fi AP may result in reduced performance (e.g. if the Wi-Fi AP is served by lower bandwidth in the backhaul than the cellular base station presently serving the device). Evaluation of criteria beyond wireless capabilities prior to access selection can be used to mitigate this.
4) Ping-Pong: This is an example of reduced end user experience due to ping-ponging between Wi-Fi and cellular accesses. This could be a result of premature Wi-Fi selection and mobility in a cellular environment with signal strengths very similar in both access types. Hysteresis concepts used in access selection similar to cellular IRAT, applied between Wi-Fi and cellular accesses can be used to mitigate this.

Here is the paper:

Integration of Cellular and Wi-Fi Networks from Zahid Ghadialy

ANDSF: Evolution and Roaming with Hotspot 2.0

Access Network Discovery and Selection Function (ANDSF) is still evolving and with the introduction of Hotspot 2.0 (HS 2), there is a good possibility to provide seamless roaming from Cellular to Wi-Fi, Wi-Fi to Wi-Fi and Wi-Fi to Cellular.

There is a good paper (not very recent) by Alcatel-Lucent and BT that explains these roaming scenarios and other ANDSF policies related information very well. Its embedded below:

TDD-FDD Joint CA

From a recent NTT Docomo presentation (embedded below). Whereas right now 3GPP has only been working on FDD or TDD scenarios, this proposal is a combination of FDD as P-Cell and TDD as S-Cell. Inter-Technology carrier aggregation is another possible option. Anyway, the complete presentation is below.

LTE-Advanced Enhancements and Future Radio Access Toward 2020 and Beyond from Zahid Ghadialy

Updated on 29/10/2013

3GPP has already started working on this work item. See RP-131399 for details.

Korea Telecom ‘Route Decision System’ for midnight buses

Interesting presentation from Korea Telecom in LTE Asia 2013 about how they use Big Data to decide the night bus routes. Here are two pics which are self explanatory

We will soon start seeing operators using the data being collected from users and this can also be a nice little earner for them.