Saturday, March 23, 2013

LTE for Public Safety Networks

The last presentation on this topic couple of months back has reached nearly 7K views so here is another one from a recent article on the same topic from IEEE Communications Magazine



Monday, March 18, 2013

From M2M Communications to IoT

M2M was again in the news recently when a new report suggested that it would be $1 Trillion industry. Back in december I posted a detailed presentation on M2M that has now crossed over 6K views. This shows that there is an appetite for this topic. So here is a three part presentation on M2M and IoT. In fact as I pointed out in a post last year, it is very often referred to as IoE (Internet of Everything) rather than IoT (Internet of Things). If this is a topic close to your heart then please do come to the Future of Wireless International Conference (FWIC) organised by Cambridge Wireless on 1st and 2nd July 2013. Details here.










Thursday, March 14, 2013

What is WebRTC and where does it fit with LTE and IMS

This simple video from MWC should give an idea on what WebRTC is and can do:


So what exactly WebRTC is in technical terms. Here is a recent presentation from WebRTC Conference and Expo



And here is another presentation that explains where it fits in with the LTE Architecture.



Dean Bubley from Disruptive Analysis has writted extensively on this topic and his recent post "Is the telephony "threat" from VoIP & WebRTC about competition or contextualisation?" is an interesting read.

Iain Sharp from Netovate recently pointed out that 3GPP have 'nearly' approved a work item for WebRTC access to IMS.

It would be interesting to see how operators will view WebRTC. As an opportunity or as a threat. Please feel free to air your opinions via comments.

Monday, March 11, 2013

DAS or 'Small Cells' and What is DAS anyway?

Its been a while I posted something on DAS (a.k.a. Distributed Antenna System). The articles I have posted have been mainly from AT&T and are here, here and here.

Picture source: The IET

Recently I read something interesting from IDG here:
According to Rob Bruce, Chief Operating Officer at distributed antenna system (DAS) vendor Axell Networks, a building is an asset, and that asset wants to deliver all the services it can in the simplest and most economical way.
"You wouldn't put five separate lighting systems into a building because there are five separate tenants in that building. You would put one in, and it becomes a utility for that building," Bruce told Techworld.
"Our view of life is it's the same for cellular coverage. You put one system in which covers the building. That is then a utility for the building, and operators can then connect into that infrastructure - that's how a DAS system works."
Bruce said that small cells are very good for single operator environments, when a single operator wants to add some capability into a particular area. But if they want to put multiple technologies into that environment then they have to put in multiple small cells.
So if a company in the UK wants to put GSM, UMTS and LTE into an office block, it has to install three small cells. If it wants to make that truly operator agnostic, it will probably have to put in 12 units, because each of the four operators uses at least three spectrum bands.
Axell Wireless recently installed a multi-operator DAS in The Shard in London, using 20 remote units to cover the whole building. Bruce claimed that, if the same thing had been done using small cells, it would involve over 100 units.
"So the building owner is saying I've got 100 lumps of intelligent electronics gadgetry that is scattered all over my building, and there's 4 different operators wanting access to all those different things in private flats, hotels and offices - it's just an operational nightmare," said Bruce.
Complete article is available here.

This is an interesting point because the Small Cells are still not evolved enough so that a single one can serve multiple operators, etc. Note that I am differentiating the closed residential femtocells from the public access small cells. Maybe a service such as FaaS or 'Femto as a Service' can help solve this problem. Based on my previous sentences, some of you may say that it should be called Small Cell as a Service (SCaaS) rather than FaaS but unfortunately that term has come to mean something else as can be seen here.

While initially the in-building solutions were mainly for coverage reasons, this may no longer be the only reason. Capacity is also an issue, especially in-building. Small cells can certainly help in the capacity area much more than DAS. Fortunately as most new phones are coming with inbuilt Wi-Fi chipsets and WiFi is available indoors in plenty, the capacity issue may no longer be a problem indoors. Again this is an area where we can have lots of discussions and each party with a vested interest can argue their case.

Here are couple of interesting videos from youtube that explain DAS:




There is also an interesting presentation by NEC in the Small Cell Americas event, embedded below:



Friday, March 8, 2013

802.11u, Passpoint and Hotspot 2.0 (HS 2.0)

Came across this interesting Video on Youtube explaining 802.11u that is embedded below.




A bit more detailed presentation on the same topic by Ruckus is also embedded below:


Related posts:


Tuesday, March 5, 2013

Technologies from Mobile World Congress 2013 (#MWC13)

If you liked the Gadgets roundup from yesterday then you would like this one as well:



You can read more about this topic here.



You can read more about this here.











You can read more about this here.


Finally:

Wednesday, February 27, 2013

Wi-Fi & Packet Core (EPC) Integration

Yesterday I wrote a blog post on whether Wi-Fi is the third RAN in the Metrocells blog. Today I am posting this excellent presentation that details how this Wi-Fi integration with EPC will be done.



Monday, February 25, 2013

LTE-A: Downlink Transmission Mode 9 (TM-9)

When LTE was introduced in Release-8 it had 7 transmission modes that were increased to 8 in Release-9. Earlier, I posted an R&S whitepaper on the different Transmission modes (10K+ views already) that listed transmission modes till TM 8. In Release-10 (LTE-A) 3GPP Introduced a new transmission mode, TM 9. TM9 is designed to help reduce interference between base stations to maximise signal stability and boost performance. The new TM-9 enables the enhancement of network capabilities and performance with minimum addition of overhead. TM9 is designed to combine the advantages of high spectrum efficiency (using higher order MIMO) and cell-edge data rates, coverage and interference management (using beamforming). Flexible and dynamic switching between single-user MIMO (SU-MIMO) and an enhanced version of multi-user MIMO (MU-MIMO) is also provided.



A new Downlink Control Information (DCI) format - known as format 2C - is used for TM9 data scheduling. Two new reference signals are defined in TM9: Channel State Information Reference Signal (CSI-RS) and Demodulation Reference Signal (DMRS). The first is used from the UE to calculate and report the CSI feedback (CQI/PMI/RI), while the latter is an evolution - providing support for more layers - of the UE specific reference signal that is already used for beamforming in Rel-9, and is used for signal demodulation. TM-9 is particularly smart as it can detect when a mobile device is being used and send a different type of signal that is optimal for a mobile device (variable DM-RS – demodulation reference signals). This maximises the efficient use of the base station and guarantee’s a decent data rate for users.


Early results in SK Telecom press release are positive with a claimed 10-15% increase in data rates in locations where there was known inter-cell interference.

I also looked into couple of books and here is one explanation from An Introduction to LTE by Chris Cox.


To use eight layer spatial multiplexing, the base station starts by configuring the mobile into a new transmission mode, mode 9. This supports both single user and multiple user MIMO, so the base station can quickly switch between the two techniques without the need to change transmission mode.

The base station schedules the mobile using a new DCI format, 2C. In the scheduling command, it specifies the number of layers that it will use for the data transmission, between one and eight. It does not have to specify the precoding matrix, because that is transparent to the mobile. The base station then transmits the PDSCH on antenna ports 7 to 7 + n, where n is the number of layers that the mobile is using. The maximum number of codewords is two, the same as in Release 8.

The mobile still has to feed back a precoding matrix indicator, which signals the discrepancy between the precoding that the base station is transparently providing and the precoding that the mobile would ideally like to use. Instead of using the PMI, however, the mobile feeds back two indices, i1 and i2. Both of these can vary from 0 to 15, which provides more finely-grained feedback than the PMI did and in turn improves the performance of the multiple user MIMO technique. The base station can then use these indices to reconstruct the requested precoding matrix.


Embedded below is an extract from Google books for Lte-Advanced Air Interface Technology By Xincheng Zhang, Xiaojin Zhou