Observed Time Difference Of Arrival (OTDOA) Positioning in LTE

Its been a while I wrote anything on Positioning. The network architecture for the positioning entities can be seen from my old blog post here. 

Qualcomm has recently released a whitepaper on the OTDOA (Observed Time Difference Of Arrival) positioning. Its quite a detailed paper with lots of technical insights.

There is also signalling and example of how reference signals are used for OTDOA calculation. Have a look at the whitepaper for detail, embedded below.

Observed Time Difference Of Arrival (OTDOA) Positioning in 3GPP LTE from Zahid Ghadialy

LA-LTE and LAA

Recently came across a presentation by Ericsson where they used the term LA-LTE. I asked a few colleagues if they knew or could guess what it means and they all drew blank. I have been blogging about Unlicensed LTE (a.k.a. LTE-U) on the Small Cells blog here. This is a re-branding of LTE-U

LA-LTE stands for 'Licensed Access' LTE. In fact the term that has now been adopted in a recent 3GPP workshop (details below) is Licensed Assisted Access (LAA).

Couple of months back I blogged in detail about LTE-U here. Since then, 3GPP held a workshop where some of the things I mentioned got officially discussed. In case you want to know more, details here. I have to mention that the operator community is quite split on whether this is a better approach or aggregating Wi-Fi with cellular a better approach.

The Wi-Fi community on the other hand is unhappy with this approach. If cellular operators start using their spectrum than it means less spectrum for them to use. I wrote a post on the usage of Dynamic Spectrum Access (DSA) Techniques that would be used in such cases to make sure that Wi-Fi and cellular usage does not happen at the same time, leading to interference.

Here is a presentation from the LTE-U workshop on Use cases and scenarios, not very detailed though.

Finally, the summary presentation of the workshop. As it says on the final slide "The current SI proposal focuses on carrier aggregation operations and uses the acronym LAA (Licensed Assisted Access)", you would be seeing more of LAA.

3GPP workshop on LTE in unlicensed spectrum, June 13, 2014: Chairman Summary from Zahid Ghadialy

Case Study: LTE for real time news gathering by Sky News

Back in May, I had the pleasure of listening to a talk by Richard Pattison from Sky News where he talked about how they have managed to start replacing their Satellite trucks (which are extremely expensive to own and run) with the new solutions using LTE.

One of the advantage of LTE over 3G/HSPA+ is that the uplink is as good as the downlink which wasn't really the case in earlier generations. What this means is that you can use your phone to do a live video call and use that for broadcasting of real time information. The Sky News Tech team has some interesting tweets on this.

We're broadcasting live from a Bradford City supporters bus on the M1 using a smartphone. Here's my view. pic.twitter.com/i2MXtXNht8
— Nick Martin (@NickMartinSKY) February 24, 2013

An example of the video quality could be seen from this clip here:

The Dejero App is an interesting one that can allow bonding of Cellular + WiFi and provide a combined data rate.

I was having a discussion yesterday on Twitter because we term this bonded cellular and WiFi as 4.5G. There are many proprietary solutions available for using them together but the standardised one is coming in standards soon.

Sky news have managed to set up new standards by having 12 feeds simultaneously broadcasting  (all based on Iphones and Ipads) during the European elections.



All this has been possible due to an amazing 4G network by EE and being able to negotiate a 500GB (0.5TB) data package.

In case you've ever wondered, this is what 500GB of mobile data looks like... #EE #4GEE pic.twitter.com/7v27RncK
— Sky News Tech Team (@skynewstech) February 19, 2013

Anyway, you can read the complete paper below:

Taking 5G from vision to reality

This presentation by Moray Rumney of Agilent (Keysight) in Cambridge Wireless, Future of Wireless International conference takes a different angle at what the targets for different technologies have been and based on that what should be the targets for 5G. In fact he has an opinion on M2M and Public safety as well and tries to combine it with 5G. Unfortunately I wasnt at this presentation but from having heard Moray speak in past, I am sure it was a thought provoking presentation.

Taking 5G from vision to reality from Zahid Ghadialy

All presentations from the Future of Wireless International Conference (FWIC) are available here.

Cell capacity and Opportunistic Use of Unlicensed and Shared Spectrum

One very interesting presentation from the LTE World Summit was about Improving the cell capacity by using unlicensed and shared spectrum opportunistically. Kamran Etemad is a senior advisor to FCC & UCMP and even though he was presenting this in his personal capacity, it reflected some interesting views that are quite prevalent in the USA.

If you don't know about Dynamic Spectrum Access Schemes, I wrote a post on the Small Cells blog here. The slide above is quite interesting as it shows the possibility of a 'Generalized' Carrier Aggregation in 3GPP Release-13. Personally, we believe that LTE + WiFi working together will be far more successful than LTE + LTE-U (unlicensed). As the blog readers would be aware, we have been pushing our vision of LTE + Wi-Fi working together; which we are calling as 4.5G. In case if you have not seen, our whitepaper is here.

The presentation is embedded below for reference:

Improving Cell Capacity of 5G Systems Through Opportunistic Use of Unlicensed and Shared Spectrum from Zahid Ghadialy

Case Study: Migrating from WiMAX to TD-LTE

I was glad to hear this case study by Mike Stacey where they have a WiMAX network already deployed and are in process of moving to TD-LTE. Along with the technical issues there are also business and customer issues that need to be taken into account while doing this technology swap. Surprisingly 3.5GHz is also not a very popular band because there are very few deployments in this spectrum. On the other hand, most of the companies worldwide that have been able to get their hands on this spectrum, generally got a big chunk (60-100MHz) so they would be able to do CA easily (bar the technical issues of Intra-band interference).

Anyway, the presentation is embedded below. Hope you find it useful. If you know of similar experiences, please feel free to add them in the comments.

Overcoming Interference Challenges when migrating from WiMAX to LTE from Zahid Ghadialy

4.5G: Integration of LTE and Wi-Fi networks

With LTE-A getting ready to meet the IMT-Advanced requirements and fulfilling the role of promised '4G', we believe the next phase of evolution before 5G will be successful interworking of LTE and Wi-Fi networks.

This whitepaper (embedded below) explores this feature, we call 4.5G, in detail.



We are very thankful to Anritsu for kindly sponsoring this whitepaper. They have their own whitepaper on this topic which is also worth a read, available here.

4.5G: Integration of LTE and Wi-Fi networks from eXplanoTech

Let us know what you think about this.

EE: The Implications of RAN Architecture Evolution for Transport Networks

Here is a presentation by Andy Sutton, EE from the recent LTE World Summit 2014. Unfortunately the event was too big to be present in all presentations but in his own words, "As always the bullet points don’t tell the full story as there’s considerable narrative that goes with this, however it does stress some major themes."

Slides embedded below, can be downloaded from Slideshare:

The Implications of RAN Architecture Evolution for Transport Networks from Zahid Ghadialy

Voice over WiFi (VoWiFi)

One of the changes that I have noticed in the last year is that some of the operators who have been opposed to WiFi in the past have not only embraced it but are now trying to monopolise the same WiFi spectrum they billed as interference prone. Personally, I think the future of Wi-Fi is not just offloading but also working together with LTE. We are billing this as 4.5G and have recently produced a whitepaper, available here.

There has been a flurry of activity on Voice over Wi-Fi in the last few months. Recently the UK operators '3' and EE announced that they are both allowing WiFi calling and SMS. While '3' customers will have to use an OTT app for the time being, EE customers will experience this seamlessly.

I heard Taqua in the recent LTE World Summit talking about their solution and have offered to share their slides (embedded below). It was interesting to find out while having a discussion with them that their solution supports 'hand-in' and 'hand-out'. This takes away a major advantage that Small Cells offered, seamless roaming. Anyway, feel free to let me know of you have any opinion on this topic

Cellular Services over WiFi from 3G4G

LTE-Broadcast: Reality check

When I wrote my blog post about why the 'Cellular Broadcast may fail again' for the Cisco SP Mobility blog, I did not realise that this would become so popular and there would be so many people writing to me to tell me why and how my assumptions are wrong and how they plan to succeed. I have not yet received a successful reasoning on why people disagree with my article and where I am wrong.

In the Video Over LTE Summit just concluded, I did not get a chance to see all the LTE-B presentations but the ones that I saw, were not convincing enough, except for one by Erol Hepsaydir, of '3' UK, that I explain in the end.

Here is my presentation from that event:

LTE-Broadcast: Reality Check from eXplanoTech

The conclusion is not self-explanatory so here it is in my own words.

I am not opposed to the operators trying LTE-B out. I wish more operators do try and hopefully we can have a model where the technology can succeed. When operators succeed in a new technology, it benefits the whole mobile ecosystem directly or indirectly. The operators have to be prepared that they may not see any return. This should not discourage them because the learnings from this may benefit in something else. The customer and their loyalty is more important. We should try and provide them with a value addition rather than think of this as a new source of revenue. People are not interested in watching the same stuff they watch on the terrestrial TV on their small devices; unique and maybe tailored content would help. Finally, don't make the billing model too complex so the users shy away from trying this new technology.

The final presentation of the event was delivered by Erol Hepsaydir of the UK operator '3'. He said that from their point of view, they are trying to have eMBMS to create additional capacity in the network. If they know that many people watch news on different apps and websites, they can offer this as a free service over broadcast. What this means is that they have gained customer loyalty and also free up the capacity for other users who are doing other data related activities. I think this is a very clever approach. He did mention though that they are only in the simulation stages and have not tried it out practically.