LTE Protocol Stack

Over the weekend, I was looking in the standards for an LTE Protocol stack and none of the diagrams seemed simple enough so I made one myself.
I also found a very detailed one on Nomor Research site.

I was also looking for some details on EMM (EPS Mobility Management) and ECM (EPS Connection Management) and found couple of (expected ;) blogs that had the required information. If interested have a look here and here.

Mobile Phone purchase, decision process...

Ajit has brought up an interesting topic in his blog and has cross referenced my presentation on "Killer Applications or Devices".

The post titled "Do single factors drives purchase of mobile devices? If so which ones?" is I would say quite important as sometimes it drives the decision process when someone is looking for a phone.

For the first time in my life I got myself a non-Nokia phone which is a Blackberry bold. My main motivation was, I can get my work emails in better format than on other phones. I am sure some of you can argue against this but when I was getting a new phone I had half an hour to make my decision and thats what I decided :)

Anyway, have a look at Ajit's post here.

Whitepaper: Voice over LTE via Generic Access (VoLGA)

Martin Sauter has published a whitepaper on VoLGA. I havent read it as of yet but I am sure it will be an interesting read for people who are interested in learning more about Voice options in LTE.

The whitepaper can be found here.

Feel free to post comments regarding the whitepaper on Martin's blog here.

Mobile Phones to replace Alarm Clocks

More than half of Brits are now using their mobile phones as alarm clocks, an alarming development for clock traditionalists.

They fear it could mean the end for dedicated alarm clocks, which have sat dutifully on our bedside tables for 150 years.

A survey of 1,500 people found that 52% had used their mobile as an alarm clock with 21% using it to get them up in the morning each day. Of course it also means you are likely to be woken up in the early hours when your do-it-all phone starts beeping because you've received an email about viagra.

A spokesperson for Rightmobilephone.co.uk - who commissioned the study - said: "The mobile phone now plays a larger more important role in our lives. "Handsets now provide us a wealth of information on the go, schedule our social occasions and as we found for many simply ensure we get out of bed each morning.



"The mobile phone is no longer for communication only, our independent handset reviews show signs of this with consumers often praising or berating the handsets camera or music quality, discounting its ability to make calls or text."

Security of Mobiles and Networks to be tested soon

Security researcher Karsten Nohl has issued a hacking challenge that could expose T-Mobile and AT&T cell phone users -- including Gphone and iPhone patrons -- to eavesdropping hacks within six months.

Nohl, a computer science Ph.D/ candidate from the University of Virginia, is calling for the global community of hackers to crack the encryption used on GSM phones. He plans to compile this work into a code book that can be used to decipher encrypted conversations and data that gets transmitted to and from GSM phones.

Nohl’s motive: he wants to compel the telecoms to address a security weakness that has been known for years. He estimates it will take 80 volunteer programmers six months to crunch the data to break the GSM encryption; 160 volunteers could cut that time to six weeks.“It looks like in a matter of months criminals world-wide will be able to intercept mobile phone conversations,” says Simon Bransfield-Garth, CEO of mobile security firm Cellcrypt. “The immediate impact is not just businesses and corporations, but potentially all of us who use mobile phones.”

The Chaos Computer Club has told the FT that in the couple of months it will be releasing code capable of cracking GSM with just a laptop and an antenna.

In comments made to the German edition of the Financial Times, the hacking group claims that governments, and criminals, are already using the technique which can break the encryption used to protect 2G GSM calls in near-real time using existing systems. The group says a public exposure of the technique will take place in the next month or two and allow anyone equipped with a laptop and an antenna to listen in to GSM phone calls.

GSM uses a range of algorithms for key generation, authentication, and encrypting connections. This latest crack is focused on the last element which relies on a range of algorithms known as A5 and numbered from zero to three. A5/0 indicates that no encryption is used, such as in countries still under ITAR* restrictions, A5/1 is the European standard that seems to be the target of this latest breach, A5/2 is used in the USA and generally considered weaker than A5/1, while A5/3 is the strongest of the lot and mandated by the 3G GSM standard.

GSM has been cracked before, the early algorithms used were weak and kept secret (and thus not exposed to public scrutiny), a situation made worse by network operators padding the keys with zeros to reduce the cost of SIM cards. This made a weak algorithm that relied on obscurity even weaker. But since then, the standard has proved surprisingly secure, and even today specialist equipment will take half an hour to break a call, so real-time listening to GSM calls has been restricted to James-Bond types with unlimited budgets.

But the Chaos Computer Club reckons they've found a way to share those super-spy eavesdropping capabilities with anyone, which should have implications for celebrities using mobile phones, but will probably have a more immediate impact on low-level drug dealers who've long relied on the security of GSM for their business.

All encryption breaks eventually, as computing power rises, and systems like GSM are designed with a specific lifetime during which the encryption is expected to remain secure. Changing the encryption is possible, but A5 is managed by the handset rather than the SIM and network operators have to support legacy handsets for long periods even if the latest models could be equipped with better encryption.

But the rest us will probably just hold tight until everyone is using 3G networks, at least in developed countries, where A5/3 is used and should remain secure for another decade or two.

Europe makes 'eCall' high priority

The European Commission has made a final call to the European governments to speed up the implementation of the 'eCall' technology that uses cellular networks to automatically alert emergency services when a road accident occurs.

Currently, the deployment of eCall is voluntary and is not being used in any EU country. The Commission warns, in a policy document, that if no significant progress is made in rolling out the system by the end of 2009 it could propose regulatory measures to make it mandatory.

The Commission has presented a policy document with a strategy for introducing an affordable in-car emergency call system in all new vehicles across Europe by 2014, starting next year. Triggered automatically, if the passengers cannot do so, eCall is claimed to be able to save up to 2,500 lives per year in the EU when fully deployed and reduce severity of injuries by 10 to 15%.




Implementing eCall needs the full collaboration of the car and telecoms industries, as well as national administrations in all EU countries who must ensure that their emergency services are equipped to handle eCalls.

Although the technology is ready and common EU-wide standards have been agreed by industry, six EU countries ( Denmark, France, Ireland, Latvia, Malta and the UK) are still not ready to commit, due to cost related concerns.

Preparing phone networks and emergency services for the roll out of eCall in cars across Europe has the full support of the European Parliament and 15 EU countries who have signed the eCall Memorandum of Understanding (Austria, Cyprus, Czech Republic, Estonia, Finland, Germany, Greece, Italy, Lithuania, Portugal, Slovakia, Slovenia, Spain, the Netherlands and Sweden) and three other European countries (Iceland, Norway and Switzerland) .

Another six countries (Belgium, Bulgaria, Hungary, Luxembourg, Romania and Poland) support eCall and are willing to sign the agreement in due time.

Before making eCall fully operational across the EU, countries must agree common standards and guidelines for harmonised deployment of the system and perform field tests putting it into practice (pilots have been launched in some EU countries, including Finland, Czech Republic, Germany, Austria, Italy, The Netherlands). Through its Competitiveness and Innovation Programme the Commission may financially support such pilots, as well as public awareness campaigns about how the technology works.

Road accidents cost the EU economy more than EUR160 billion a year. Equipping all cars in the EU with the eCall system could save EUR26 billion annually while the system' is estimated to cost less than EUR100 per car. Introducing this device will not only benefit consumers, but also businesses by enabling the car and telecoms industries to offer new upgraded applications and services (like digital tachographs or electronic tolls) based on eCall to be installed in all vehicles and use satellite positioning technology.

3G or 4G: What should India do?

The first thing I should mention as I always do, please stop calling LTE as 4G as its commonly called as 3.9G. Labelling it as 4G does make it sound better (or sexy, some would say) but its not correct. Maybe the authors who label LTE as 4G dont want to try hard and do some research or its just to make the end users panic that India has missed a complete generation of mobile technology. LTE-Advanced will be the 4G technology and its still long way away (part of Rel-10).

Last week I wrote about Indian subscribers getting taste of 3G as the state owned MTNL and BSNL have launched some services. I am not sure what has been launched but all I can say is there is a dismal takeup as of yet. I read an article today about how Motorola is testing 4G [sic] and this can spoil the governments plan of rasing Rs 35,000 crore (£4.6Billion: 1Billion = 100 crores).

People may start panicking that investing in 3G is now doomed and it can just cause problems for the operators in future. The reality though is much more simpler. In a simple sentence, I would say that going for 3G or LTE does not matter much. Read on.

Lets first get Hardware out of the way. Most of the Base Stations (NodeB's, eNodeB's, RNC, etc) have a major part as SDR's or Software Defined Radios. The advantage of this is that if you have bought a 3G Node B, with just software change it should be upgradable to LTE eNode B. I have come across quite a few products where the equipment manufacturers are claiming that their 3G equipment is fully upgradeable to LTE. I did blog about some of this in this post here.

The second point we should get out of the way is the terminology. For a layman, 3G is something that was introduced 10 years back in 2000 so its quite an obsolete technology. In reality, 3G is commonly used to refer to even the new developments within the 3G spectrum. For example some of the people may have heard of HSDPA which is actually referred to as 3.5G in the mobile domain. Similarly we have HSUPA which is 3.75G and so on. The latest development is going on around 3.8G and 3.85G as part of Release 8. In general usage 3.5G, 3.75G, etc. is referred to as 3G but its more than 3G (3G+ ;). The good thing is that this 3G+ is till evolving. Release 8 was finalised in Dec. 2008 and the terminals based on that are still being tested. It should hopefully be available soon.

So whats the difference between LTE and HSPA+ (also known as 3G even though its 3.8/3.85G). Not much I would say from a general users point of view. Please note I am not arguing about the fundamental technologies because 3G+ uses WCDMA and LTE uses OFDMA/SC-FDMA technologies. OFDM based technologies will generally be always superior to WCDMA ones but it doesnt matter much. The main enhancement that has happened with LTE as compared to 3G is that in 3G the bandwidth is fixed to 5MHz whereas in case of LTE the bandwidth is flexible and can go all the way to 20MHz. Now if we compare the data speeds in 5MHz spectrum then there may not be much difference between them. Now how many operators will be rolling out services across 20MHz bandwidth? More general case will be using 10MHz.

In case of HSPA+, there is a new feature that allows a UE to use couple of cells. In this case even though the bandwidth is 5MHz but due to Dual Cell feature the UE would effectively see 10MHz bandwidth. This will definitely enhance the speeds.

Now coming to devices. 3G/HSPA/HSPA+ technologies have evolved over quite few years. There are some nice sleek and cheap handsets available. The technology in it as been rigourously tested. As a result the handsets are quite stable and many different design and models available.

LTE is yet to come. NTT DoCoMo and Verizon will be the first one to roll it out probably end 2010. Initial plan is to roll out the dongles then handsets will the eventually arrive. The initial ones will have problems, crashes, etc. Will take atleast till 2010 to sort out everything.

The big problem with LTE as many of us know is that the standards have to support for the old style CS voice and SMS. This should be fixed in Release 9 which is going to be standardised in Dec. 2009 (Mar. 2010 practically). There are different approaches and maybe untill LTE is rolled out we wont know which of them is better.

Last thing I should mention is the spectrum. The consensus is that 3G operates in 2.1GHz spectrum mostly worldwide. LTE would initially be deployed in 2.6GHz spectrum. The digital dividend spectrum when it becomes available will also be used for LTE. Most of the devices for LTE will be designed that way. As a result, 3G will continue to operate as it is in the 2.1GHz band. The devices will always be available and will be usable for long time.

Considering all the facts above, I think 3G (HSPA/HSPA+) is the best option in India or as a matter of fact in any country that is thinking of jumping directly from 2G to LTE. When the time is right, it should not be difficult to move from 3G to LTE.

EU commits to LTE-A future

Communications industry executives have welcomed the EU's commitment to fund research work on LTE Advanced , the follow-on technology from LTE that many mobile network operators have only just started embracing, but also cautioned on the timescales involved in deploying the next generation technology.

Earlier last week, the EU said it would invest 18 million Euros ($25 million) in developing the next generation of LTE, beginning on Jan. 1, 2010.

Between 2004 and 2007, the EU supported research on optimization and standardization of LTE -- the WINNER I and II projects, run by a consortium of 41 leading European companies and universities -- with 25 million Euros.

LTE Advanced is the first version of the mobile standard that might actually match the International Telecommunication Union (ITU)'s requirements for wireless 4G networks. It promises performance in the region of 1Gbit/s downlink when the user is stationary and 100 Mbit/s on the move.

The specs for LTE Advanced are in very initial stages and will be a part of 3GPP Release 10, which is scheduled for 2011, and may slip into 2012.

LTE by itself is considered to be really a '3.9G' technology and it is LTE Advanced that will deliver on the 4G promise of minimizing differences between wired and wireless broadband speeds. LTE Advanced calls for support of peak data rates which are as high as 1Gbit/s.

The investment will provide a base for migration, as well as experience with running 4G networks - and help evaluate whether/when the upgrade to LTE Advanced will be needed.

Operators have only now started embracing LTE, and are making plans to migrate their current 3G offerings to LTE by 2012.

4 Billion GSM-HSPA connections soon.

3G Americas, announced that GSM-HSPA is expected to reach 4 billion mobile connections worldwide in September 2009. This marks a major milestone for the industry, as no other technology innovation has ever reached a scale remotely close to its penetration level – equivalent to more than six of every ten people worldwide.

In today’s global economy, which is overshadowed by recession, it is impressive to note that in the Americas region the take-up of the 3GPP evolution from GSM to HSPA grew by more than 19 percent in the year ending June 2009 (2Q) to 561 million subscribers with a market share of 72 percent. Globally, GSM-HSPA grew by 20 percent adding nearly 645 million new connections in the same 12 months.

Equally noteworthy is the increasing number of 3G subscribers for UMTS-HSPA which has captured an annual worldwide gain of 57 percent in the year ending June 2009, according to Informa Telecoms & Media’s World Cellular Information Service. With 377 million subscriptions worldwide at the end of second quarter 2009, UMTS-HSPA added more than 137 million new connections in 12 months.

The Latin America and Caribbean region continues to experience a remarkable growth curve for subscriptions to GSM-HSPA technologies. In fact, at the end of second quarter 2009, CDMA mobile technologies saw a decline in subscriptions while GSM technologies grew at an annual rate of 22 percent to more than 433 million connections with a 90 percent share of market.

Today, there are 49 UMTS-HSPA networks commercially deployed throughout 24 countries in Latin America and the Caribbean. Worldwide, 277 commercial networks offer HSPA in 116 countries. Additionally, 11 networks have been upgraded to HSPA+. According to Informa, by the year 2012, UMTS-HSPA will reach a milestone of one billion subscribers.

Mobile Search in Future...

Interesting Blog from Mohit Agrawal on the future of Mobile search.

How is Mobile Search different?

The fundamental difference between the mobile search and PC search is the access device. The screen size of the mobile phone is a constraint and hence the internet search results need to be modified. Even the input keyboard is different and the search string could be shorter which means the search result has to be intuitive.

The second difference is in the usage pattern of mobile. Unlike PC, the mobile phone is a ubiquitous device and people normally search for “at the moment” kind of thing. This means they search for nearest restaurant, retail points, service centers or mobile content. Their need is immediate and the patience or tolerance is low. They are looking for relevant results that are actionable like they need a taxi that can reach them fast and they should be able to book the taxi using their mobile phone. This means that the result needs to be location aware and should also give the phone number of the taxi company.

Thirdly, the consumer expectations changes with the time of day for the search results e.g. an afternoon search for restaurants means that the results should be about restaurants amenable to business meetings whereas, in the evening the same search should retrieve fun places like pubs or lively music restaurants.

Lastly, the difference is in the frequency of search and the number of attempts for each search.

On PC, a surfer changes his search string multiple times before he gets the right results while on a mobile, nobody is likely to change the search string more than a couple of times. Also, people search at least 4-5 different things on PC everyday but a typical mobile internet user searches something only once in 4-5 days.

There are quite a few videos which he uses to explain the point and they are interesting watch. I strongly recommend to go and have a look at the blog.

Another thing that will become important is the advertisements within the search. If I am looking for a day out on the weekend and if I get another option while searching for my destination then I may be tempted. While out and about, search for restaurants or the nearest MacD may may give some tempting offers about from other restaurants.

I can see lots of potential in mobile search and I am sure that there are companies that are working towards them. Its just matter of time before another new player like YouTube, Facebook or Skype may become leader of this domain.