Tuesday, 19 May 2009
LTE World Summit - Day 1 roundup
Before we start, I should mention that there have been no discussions showing LTE is better than WiMAX, etc. It is now assumed that WiMAX is no longer a threat and a competitor. There is also missing a discussion on Femtocells. I suppose that some Femto related discussions are planned for day 3.
I am going to cover the discussions in detail in the coming days (months) but here are some interesting tidbits.
It started with a presentation from Marc Fossier, France Telecom. An interesting fact about France he mentioned is that 40% of voice traffic is VoIP. They are present in 30 countries (generally by the name Orange) and they have 128 million customers. LTE rollout is planned for post 2011. They will be deploying WiMAX in some markets like Romania and some African countries. The main reason being that there is no 3G network there. Another key point of his presentation was that Mobile TV should be independent of the technology being considered and TDD works fine for that. Also SON (Self Organising Networks) will be very important feature that is needed when LTE is rolled out.
Klaus-Jurgen Krath from T-Mobile Germany gave T-Mobile statistics of 148 million customers and revenue of 9.2 Billion Euros. One of the things he mentioned is that at 2.6GHz, the cell radius is 0.3Km but if we move to 800MHz then the cell radius is around 3Km. Personally I am not sure if the frequency is something we should worry too much about. WiBro in Korea is I think using 2.3GHz and is working fine. Another thing mentioned is that the Backhaul is generally quite bandwidth limited so that needs to be improved. The operators should use Microwave or Fiber to overcome this backhaul problem. LTE Migration will also take time and initially it would be the third layer on top of GSM and 3G/HSPA but by 2020 it should be dominant technology. Right now Voice and SMS problem has to be solved asap. Personally I think SMS is not much of a problem and SMS can work on CS as well as PS. Operators can use SMS over PS for the moment. Femtocell according to Klaus is very important for LTE but Femtos will be successful only if they are Plug and Play for both operator and the consumer. His final point was that we should not dissapoint the customer by showing the peak rates, rather we should focus on average rate.
Ulf Ewaldsson from Ericsson mentioned that 80% of broadband subscribers by 2014 will be mobile. Another thing he said is that for LTE, it is possible to deliver 1GB for < 1 euro. (Capex only). Ericsson vision is that by 2020 there will be 50 Billion mobile broadband connections. Ericsson will be ready with LTE soon and by the year end peak rate of 42Mbps will be possible.
Alex Sinclair from GSMA talked on expanding the LTE ecosystem. There were lots of interesting facts and figures that I will have to mention seperately. There was also an intersting mention of the GRX (GPRS Roaming Exchange) that will need a completely new discussion.
In the Panel Discussion, Marc mentioned that Orange is not considering Femtocells for Residential market because of many unsolved technical problems like Price, Security, Spectrum Management, etc. On the business side they may have Femto, Pico or Micro depending on the need. Ed Candy from '3' mentioned that operators should focus on Macro rather than Femto because lots of spare capacity available. He mentioned that there is a business problem because somebody has to subsidise Femto, also too many Femtos can cause RF blackspots and operational dynamics are yet to be worked out.
Elio Florina from Telecom Italia (TiM) talked about LTE and HSPA deployment in Brasil. The main point being that initially they want to have complete 3G/HSPA coverage and then in future think about LTE.
Alan Hadden from GSA mentioned about GSA activities. I was surprised to hear that only 55,000 people view their website annually. This is because a simple blog like mine regularly gets between 20,000 and 25,000 views per month. Again there were lots of stats that I will write about later. Interesting point from his discussion was about the Digital Dividend band that can be used by LTE to increase the coverage.
Dave Marutiak, Microsoft spoke about Bearer Aware Applications. Dean has blogged in detail about this.
Ed Candy from '3' in his presentation highlighted an important point about the user experience. He said that for any service, user experience should be memorable so even after 2-3 years if the user has to use the same application than he should remember how it works. I think that there are hardly any services like this except those that are intutive to use. In Dec. 08, '3' saw people using 34million skype minutes and 68 million Facebook page views. It should be remembered that Facebook phone was launched in Dec itself. His message was that '3' will not be moving to LTE anytime soon because the current network is delivering whatever is required.
Roberto Di Pietro from Qualcomm spoke about the challenges faced by the chipset manufacturers. The main challenges is due to the fact that there are millions of combinations of different bands that the UE may need to support which is not practical and possible. They are focussing mainly on 2.6GHz at the moment and when the Digital Dividend band is available then they will implement chipset in that band as well.
Jorgen Lantto from ST-Ericsson and Sami Jokinen from Nokia gave their views on chipsets and handsets implementation respectively. According to Nokia, LTE handsets will be available by 2010. Initial deployments will be in FDD but later in TDD-FDD both.
Liesbet Van der Perre from IMEC discussed about the SDR implementation for LTE devices. Her presentation was more of updates on the previous IMEC info I have covered here.
Finally, I managed to squeeze myself into an Agilent workshop called 'LTE at the movies'. There were two parts to that 'MIMO MIA' and 'Honey who shrunk my mega bits'. The workshop lated 2.5 hours and I got a free Agilent LTE book. Lots of technical details that I will post seperately.
Please feel free to comment or correct me if I made any mistakes. You can also read Dean Bubley's take on the first day here.
I shouldnt finish without thanking the organisers who have done a good job in organising the event and for such wonderful hospitality (and food :).
LTE World Summit - Day 1 Pics
Setcom is a new entrant (even though they have been present for long time but I never heard of them before) in Network Simulator area. They have plan to do Conformance tests for the LTE mobile. They claim to be ready already with basic test functionality. Till date the Conformance test market have been dominated by Anritsu, Agilent (Anite), Aeroflex and R&S. I have already heard of AT4 Wireless being active in this area for LTE. It would be interesting to see one more player.
Monday, 18 May 2009
In Berlin for LTE World Summit
Here are some photographs from Berlin:
All the above photographs are from The ruins of the Kaiser Wilhelm Memorial Church in Berlin, destroyed by Allied bombing in Second World War and preserved as a memorial
Saturday, 16 May 2009
New LTE Patent Pool attempt
“The market is ready, and we are proud that industry leading companies have invited us to facilitate creation of an LTE pool license,” said MPEG LA President and CEO Larry Horn. “Given the history of telecommunications patent pools, MPEG LA has taken the time to consult directly with mobile network operators, network equipment manufacturers and mobile handset companies regarding the benefits of a patent pool for LTE, and they have encouraged MPEG LA to move forward with this effort. We are pleased by their vote of confidence. Next generation wireless technology, with its multifunctional capabilities, begs for a patent pool licensing alternative to make its full potential available to consumers worldwide, and MPEG LA’s success in creating large pool licenses uniquely positions us to achieve it.”
Patent pools have become increasingly popular in recent years to handle licensing in cases of relatively large numbers of patent holders and licensors. The pools can help lower transaction costs and reduce uncertainty and time spent negotiating deals, sometimes with competitors across barriers of language and geography.
Friday, 15 May 2009
Testing UMTS protocols
Testing UMTS by Dan Fox, Anritsu
Its nearly three years since I wrote an FAQ on UMTS Testing. So when I got my hands on this book the other day, I so wanted to read it. It would be a while before I manage to go through the book in detail but my initial impression is that this book looks quite good.
Since the book deals with Protocol Testing, the testing has been grouped into three categories:
- Integration Testing
- Conformance Testing
- Interoperability Testing
There is a chapter explaining each of these. The Conformance testing is of interest to me as I have been involved directly and indirectly with this for quite some years now. The book explains the process, standards required and submission of tests to GCF/PTCRB.
For those whom testing does not hold much charm, they can gain greater understanding of the concepts by reading Part II of the book. One thing I really liked in this book is that the diagrams explain the concepts very well. Rather than copying them straight from the 3GPP specifications, they have been improved and re-done by the author. Basic things like 'Dynamic TFCI selection' and 'Layer 2 transport channel processing flow for the 12.2 kbps RMC' are explained clearly using the diagrams.
There is just the right amount of detail in the chapters for Physical Layer, Layer 2 (MAC, RLC, PDCP) and Layer 3 (RRC, NAS). Further chapters show message flow sequence charts explaining things like 'setting up of speech call' and 'location updating procedure'. I have some basic sequence diagrams for message flow in the Tutorial section but the ones in the book are comparatively more detailed.
The book mainly covers UMTS, with an introduction to HSPA. It would be worthwhile to have the next edition covering LTE in detail. The main reason being that there are lots of changes in the case of LTE. The Air Interface has changed, the channels are different. The NAS messages and entities are different. UMTS (and HSPA) use TTCN-2 for testing but LTE uses TTCN-3. UMTS does not use MIMO (MIMO available for HSPA from Release 7 onwards) but LTE would generally always use MIMO.
Overall, this seems to be a useful book and I am looking forward to reading it in detail.
Golden-i: Futuristic Bluetooth Headset with Virtual PC Display
Thursday, 14 May 2009
Inter symbol and inter carrier interference (ISI and ICI) in OFDMA
- Large scale fading: It is the fluctuation in the average signal strength over a large distance and is caused by terrestrial change. This occurs when a mobile travel from a lake to mountainous are to a lake area or from an open area to a tall buildings area. Large scale fading can be mitigated by controlling the transmit power.
- Small scale fading: Occurs as a result of the fluctuations in the received signal strength over a small distance and is caused by multipath and Doppler's shift. Doppler shift refers to the change on frequency of the signal because of relative motion between the transmitter and the receiver.
The figure here shows the multipath propagation for a signal. Signal goes from transmitter to the receiver through multipath that have different lengths i.e. path 1, path2 and path 3. The signal from different path arrives at the receiver at different times although it’s originated from the same source. The received symbol as shown below is longer than the duration of the original symbol.
Delay spread can cause adjacent symbols to interfere at the receiver. As a result of the multipath the delayed version of the first symbol shifts into the next symbol time and thus causes overlap between he symbols. In OFDMA this is taken care of where more time is give for each symbol to be received at the receiver by inserting a guard time.
The Doppler shift introduces another type of interference in OFDMA i.e. inter carrier interference (ICI). OFDMA divided the spectrum into narrowband subcarriers and they are tightly spaced simply because they are orthogonal. One of the requirements for orthogonality is to maintain the subcarrier spacing exactly the reciprocal of the symbol period. The figure below shows the frequency shifts thus changing the subcarrier spacing which results in the loss of orthogonality. This loss of orthogonality creates interference among the signals which is called as ICI. Since the subcarriers in OFDMA are usually very narrow hence the OFDMA system becomes very sensitive to ICI. ICI destroys the orthogonality of the OFDMA system which is overcome by the use of cyclic prefix mechanism.
Under this mechanism OFDM symbols are extended into periodical symbols i.e. redundant information is sent out to ensure that analysis can be conducted on the undistorted information and is called as cyclic extension.
It can be implemented by copying the portion of the original symbol from the end and attaching it to the front or copying it from the front and attaching it to the end. Since OFDMA has already assigned the guard time to defeat ISI, cyclic extension can be put into the guard time interval. This is called cyclic prefix. With cyclic prefix used the delayed version of the previous symbols cannot shift into the useful time of the current symbol so ISI is eliminated as well. Also the cyclic prefix provides redundant information and allows spectral analysis in the receiver to maintain the orthogonality of the subcarriers. Thus the cyclic prefix can be used to deal with both ISI and ICI.
The above concepts can be summarized in teh form of the picture below
Vodafone (JIL) to release new APIs to third parties
Wednesday, 13 May 2009
Surround Sound transmission technology from NTT DoCoMo
NTT DOCOMO, INC. announced that it has developed a highly efficient mobile spatial audio transmission technology that enables a mobile phone user to assign a spatial position to each sound source when listening to multiple sound sources, such as during a game or a conference call.
While existing spatial audio transmission technologies independently process audio encoding/decoding and spatial audio synthesis, the new technology offers a more efficient method by integrating the two processes, thereby minimizing bitrate (or bandwidth) and computation loads suitable for mobile phones and other resource-limited devices.
The processes are collaboratively performed on both the server and client sides. The server identifies the important sound components of each speaker's voice, compresses them efficiently into a single stream and transmits it to the mobile phones. Each phone then decodes the received stream and simultaneously synthesizes spatial audio images
DOCOMO is demonstrating its new spatial audio transmission technology using docomo PRO series™ HT-01A handsets during Wireless Technology Park 2009 at Pacifico Yokohama on May 12 and 13.
Tuesday, 12 May 2009
iPhones in the War Zone
Tying the hands of a person who is speaking, the Arab proverb goes, is akin to "tying his tongue." Western soldiers in Iraq know how important gestures can be when communicating with locals. To close, open and close a fist means "light," but just opening a fist means "bomb." One soldier recently home from Iraq once tried to order an Iraqi man to lie down. To get his point across, the soldier had to demonstrate by stretching out in the dirt. Translation software could help, but what's the best way to make it available in the field?
The U.S. military in the past would give a soldier an electronic handheld device, made at great expense specially for the battlefield, with the latest software. But translation is only one of many software applications soldiers now need. The future of "networked warfare" requires each soldier to be linked electronically to other troops as well as to weapons systems and intelligence sources. Making sense of the reams of data from satellites, drones and ground sensors cries out for a handheld device that is both versatile and easy to use. With their intuitive interfaces, Apple devices—the iPod Touch and, to a lesser extent, the iPhone—are becoming the handhelds of choice.
The sheer versatility of the kit – with the capability of over 30,000 programmes – allows a huge variety of functions needed for operations ranging from providing language translations to the transmitting of sensitive information and working out trajectories for snipers. Projects are on the way to use them as guidance systems for bomb disposal robots and receivers of aerial footage from unmanned drone aircraft.
The US Marine Corps is funding an application that would allow soldiers to upload photographs of detained suspects, along with written reports, into a biometric database. The software would match faces, in theory making it easier to track suspects after they're released.
Members of the British military who have seen the Apple instruments in action drool about the opportunities on offer. The Ministry of Defence, however, remains wary of security implications and has "no plans" at present to go down the American path.
But Lieutenant Colonel Jim Ross, the director of the US Army's intelligence, electronic warfare and sensors operation, believes the iPod "may be all that the personnel need".
"What gives it added advantage is that a lot of them have their own personal ones so they are familiar with them," he said.
Another plus is the cost. The iPod touch (which soldiers can use over a secure WiFi network) retails for around $230 (£150) and the iPhone for $600. Bulk orders placed by the Pentagon bring further savings. The manufacture of a specific military model would be much more expensive.
Robert Emerson, a security analyst who has advised foreign governments on computerised warfare, said: "The US military has had a reputation for being somewhat heavy handed, with justice. But what they are doing with iPods and iPhones show they can also be nimble on their feet. Other militaries should learn to be equally open minded."