Sunday, 28 June 2015

LTE-M a.k.a. Rel-13 Cellular IoT

Some months back I wrote about the LTE Category-0 devices here. While Rel-12 LTE Cat 0 devices are a first step in the right direction, they are not enough for small sensor type of devices where long battery life is extremely important. As can be seen in the picture above, this will represent a huge market in 2025.

To cater for this requirement of extremely long battery life, it is proposed that Rel-13 does certain modifications for these low throughput sensor type devices. The main modification would be that the devices will work in 1.4MHz bandwidth only, regardless of the bandwidth of the cell. The UE transmit power will be max of 20dB and the throughput would be further reduced to a maximum of 200kbps.

The presentation, from Cambridge Wireless Future of Wireless International Conference is embedded below:

See also:

Sunday, 21 June 2015

Broadband Access via Integrated Terrestrial & Satellite Systems

Last week I attended an event in the University of Surrey that was about providing high speed connectivity to un-served and under-served areas in future. While there is no arguing that satellites are a great option for unserved areas, the underserved areas can really benefit by such initiatives.

The way this is being proposed is to have a specialised Intelligent User Gateway (IUG) that can connect to ADSL, Mobile and Satellite. The assumption is that in areas of poor conectivity, ADSL can provide 2Mbps and the mobile could do something similar, upto 8Mbps. The satellites can easily do 20Mbps.

While the satellite broadband has the advantage of high speeds, they often suffer from high latencies. ADSL on the other hand has very small latency but may not be good enough for streaming kind of applications. Mobile generally falls in between for latency and speed. Using Multipath TCP and some intelligent routing algorithms, decisions can be taken to optimise for latency and speeds.

I did see some impressive demo's in the lab and it did what is says on the tin. The real challenge would be the business models. While ADSL can offer unlimited internet, both Mobile and Satellite broadband will have caps. I was told that limits could be imposed so that once the Mobile/Satellite data allowance is over, only ADSL would be used. Maybe a more complex algorithm could be implemented in future that can include cost and priority of the application/service being used.

An example would be that sometimes I want to watch some long videos over Youtube but I am happy to start buffering an hour in advance. Its not critical that I have to watch that now. I would be more than happy to save my Mobile/Satellite broadband data allowance for some other day when I need to watch things more urgently. If the end of month is coming and I have a lot of data allowance left then maybe I dont mind using the quota otherwise I will anyway lose the allowance. Its always challenging to put this intelligence in the routing decision algorithms though.

Anyway, the combined presentations are embedded below and you can download them from the BATS project page here:

Tuesday, 16 June 2015

Have researchers moved on past 5G on to 6G Wireless?

As I am active on multiple social networks including blogs, twitter, facebook, linkedin, etc., Its always tricky to be able to share information from one on to another. Some time back I tweeted about the 6G research that seems to have started according to an article in FT.

While I had a few retweets and interactions, I realised that its always challenging to search the tweets so I decided to add this in the blog post, always easier to look it up.

So the FT Article states that:

Even as 5G remains a distant prospect for most mobile users, some scientists have already begun to work on plans for 6G services in the future.

To an extent, terms such as 4G and 5G have become as much about marketing equipment as any single technology breakthrough, with incremental improvements to technical specifications often arbitrarily given names such as 3.5G or 4.5G.

But that has not stopped people from thinking about what 6G could look like — and in the UK at least, the prediction is for a “quantum” leap.

Britain has created a “national quantum strategy” to identify areas where advances in technology will have the greatest impact on daily lives in the future. The strategy was developed by the Quantum Technologies Strategic Advisory Board, a government funded agency, which oversees the £270m programme. 

One of the key goals will be the development of faster communications for mobile devices. The advisory board predicts that the market for quantum products and technology has the potential to become a £1bn industry, even if details of how mobile technology can use quantum theory — science at an atomic level — are thin on the ground.

So why did I suddenly think about 6G? Because I have had a few discussions where the research community feel that they should focus on technologies beyond 5G, something that would be a game changer and would change the way we do communications. To be honest, new ways of communications have been found (like LED-Fi / Li-Fi ) but they have not really been ground breaking.

Do you have any ideas or suggestions, add it as comments.

Sunday, 14 June 2015

Using 8T8R Antennas for TD-LTE

People often ask at various conferences if TD-LTE is a fad or is it something that will continue to exist along with the FDD networks. TDD networks were a bit tricky to implement in the past due to the necessity for the whole network to be time synchronised to make sure there is no interference. Also, if there was another TDD network in an adjacent band, it would have to be time synchronised with the first network too. In the areas bordering another country where they might have had their own TDD network in this band, it would have to be time synchronised too. This complexity meant that most networks were happy to live with FDD networks.

In 5G networks, at higher frequencies it would also make much more sense to use TDD to estimate the channel accurately. This is because the same channel would be used in downlink and uplink so the downlink channel can be estimated accurately based on the uplink channel condition. Due to small transmit time intervals (TTI's), these channel condition estimation would be quite good. Another advantage of this is that the beam could be formed and directed exactly at the user and it would appear as a null to other users.

This is where 8T8R or 8 Transmit and 8 Receive antennas in the base station can help. The more the antennas, the better and narrower the beam they can create. This can help send more energy to users at the cell edge and hence provide better and more reliable coverage there.  

SONWav Operator Solution

How do these antennas look like? 8T8R needs 8x Antennas at the Base Station Cell, and this is typically delivered using four X-Polar columns about half wavelength apart. I found the above picture on antenna specialist Quintel's page here, where the four column example is shown right. At spectrum bands such as 2.3GHz, 2.6GHz and 3.5GHz where TD-LTE networks are currently deployed, the antenna width is still practical. Quintel’s webpage also indicates how their technology allows 8T8R to be effectively emulated using only two X-Polar columns thus promising Slimline antenna solutions at lower frequency bands. China Mobile and Huawei have claimed to be the first ones to deploy these four X-Pol column 8T8R antennas. Sprint, USA is another network that has been actively deploying these 8T8R antennas.

There are couple of interesting tweets that show their kit below:

In fact Sprint has very ambitious plans. The following is from a report in Fierce Wireless:

Sprint's deployment of 8T8R (eight-branch transmit and eight-branch receive) radios in its 2.5 GHz TDD LTE spectrum is resulting in increased data throughput as well as coverage according to a new report from Signals Research. "Thanks to TM8 [transmission mode 8] and 8T8R, we observed meaningful increases in coverage and spectral efficiency, not to mention overall device throughput," Signals said in its executive summary of the report.

The firm said it extensively tested Sprint's network in the Chicago market using Band 41 (2.5 GHz) and Band 25 (1.9 GHz) in April using Accuver's drive test tools and two Galaxy Note Edge smartphones. Signals tested TM8 vs. non-TM8 performance, Band 41 and Band 25 coverage and performance as well as 8T8R receive vs. 2T2R coverage/performance and stand-alone carrier aggregation.

Sprint has been deploying 8T8R radios in its 2.5 GHz footprint, which the company has said will allow its cell sites to send multiple data streams, achieve better signal strength and increase data throughput and coverage without requiring more bandwidth.

The company also has said it will use carrier aggregation technology to combine TD-LTE and FDD-LTE transmission across all of its spectrum bands. In its fourth quarter 2014 earnings call with investors in February, Sprint CEO Marcelo Claure said implementing carrier aggregation across all Sprint spectrum bands means Sprint eventually will be able to deploy 1900 MHz FDD-LTE for uplink and 2.5 GHz TD-LTE for downlink, and ultimately improve the coverage of 2.5 GHz LTE to levels that its 1900 MHz spectrum currently achieves. Carrier aggregation, which is the most well-known and widely used technique of the LTE Advanced standard, bonds together disparate bands of spectrum to create wider channels and produce more capacity and faster speeds.

Alcatel-Lucent has a good article in their TECHzine, an extract from that below:

Field tests on base stations equipped with beamforming and 8T8R technologies confirm the sustainability of the solution. Operators can make the most of transmission (Tx) and receiving (Rx) diversity by adding in Tx and Rx paths at the eNodeB level, and beamforming delivers a direct impact on uplink and downlink performance at the cell edge.

By using 8 receiver paths instead of 2, cell range is increased by a factor of 1.5 – and this difference is emphasized by the fact that the number of sites needed is reduced by nearly 50 per cent. Furthermore, using the beamforming approach in transmission mode generates a specific beam per user which improves the quality of the signal received by the end-user’s device, or user equipment (UE). In fact, steering the radiated energy in a specific direction can reduce interference and improves the radio link, helping enable a better throughput. The orientation of the beam is decided by shifting the phases of the Tx paths based on signal feedback from the UE. This approach can deliver double the cell edge downlink throughput and can increase global average throughput by 65 per cent.

These types of deployments are made possible by using innovative radio heads and antenna solutions.  In traditional deployments, it would require the installation of multiple remote radio heads (RRH) and multiple antennas at the site to reach the same level of performance. The use of an 8T8R RRH and a smart antenna array, comprising 4 cross-polar antennas in a radome, means an 8T8R sector deployment can be done within the same footprint as traditional systems.

Anyone interested in seeing pictures of different 8T8R antennas like the one above, see here. While this page shows Samsung's antennas, you can navigate to equipment from other vendors.

Finally, if you can provide any additional info or feel there is something incorrect, please feel free to let me know via comments below.

Sunday, 7 June 2015

Nuggets from Ericsson Mobility Report

Ericsson mobility report 2015 was released last week. Its interesting to see quite a few of these stats on devices, traffic, usage, etc. is getting released around this time. All of these reports are full of useful information and in the old days when I used to work as an analyst, I would spend hours trying to dig into them to find gold. Anyway, some interesting things as follows and report at the end.

The above chart, as expected, data will keep growing but voice will get flatter and maybe go down, if people start moving to VoIP

Application volume shares, based on the data plan. This is interesting. If you are a heavy user, you may be watching a lot of videos and if you are a light user then you are watching just a few of them.

How about device sizes, does our behaviour change based on the screen size?

What about the 50 Billion connected devices, was it too much? Is the real figure more like 28 billion?

Anyway, the report is embedded below.

Wednesday, 3 June 2015

'The Future Inter-connected Network' and Timing, Frequency & Phase requirements

I had the pleasure of doing a keynote at PhaseReady 2015 in London today. My presentation is embedded below along with some comments, followed by tweets some of which I think are important to think about. Finally, I have embedded a video by EE and Light Reading which was quoted and maybe its important in the context of this event.

My main focus during this presentation has been on how the networks have evolved from 3G days with the main focus (unconsciously) on speeds. While the networks are evolving, they are also getting more complex. The future ecosystem will consist of many Inter-connected (and in many cases inter-operable) networks that will work out the requirements in different situations and adapt to the necessary network(technology) accordingly.

An example of today's networks are like driving a manual car where we have to change gears depending on the traffic, speed required and fuel efficiency. Automatic cars are supposed to optimise this and achieve the best in all different cases. The future inter-connected networks should achieve the best based on the requirements in all different scenarios.

While it is easy to say this in theory, the practical networks will have many challenges to solve, including business and/or technical. The theme of the conference was timing, frequency and phase synchronisation. There are already challenges around them today, with the advanced LTE-A features. These challenges are only going to get bigger.

The following are the tweets from the day:

Finally, here is the link to video referred to in the last tweet. Its from last year but well worth listening.