What is (pre-5G) 4.5G?

Before we look at what 4.5G is, lets look at what is not 4.5G. First and foremost, Carrier Aggregation is not 4.5G. Its the foundation for real 4G. I keep on showing this picture on Twitter

I am sure some people much be really bored by this picture of mine that I keep showing. LTE, rightly referred to as 3.9G or pre-4G by the South Korean and Japanese operators was the foundation of 'Real' 4G, a.k.a. LTE-Advanced. So who has been referring to LTE-A as 4.5G (and even 5G). Here you go:

Got 4G? Wake up, grandad. We're doing 4.5G LTE-A in London - EE chief: And get a load of our gleaming voice system! … http://t.co/78HSHlyPuA
— The Register (@TheRegister) March 5, 2014

Voda UK PR says: "The new technology, called Carrier Aggregation but also referred to as LTE Advanced or 4.5G" 4.5G?
— Keith Dyer (@keithdyer) October 15, 2014

5G wireless technology LTE-Advanced is now running in the Philippines' largest and strongest network. | http://t.co/g8u3lJ8sLV #Smart5G
— Smart Communications (@SMARTCares) August 14, 2014

So lets look at what 4.5G is.

Back in June, we published a whitepaper where we referred to 4.5G as LTE and WiFi working together. When we refer to LTE, it refers to LTE-A as well. The standards in Release-12 allow simultaneous use of LTE(-A) and WiFi with selected streams on WiFi and others on cellular.

Some people dont realise how much spectrum is available as part of 5GHz, hopefully the above picture will give an idea. This is exactly what has tempted the cellular community to come up with LTE-U (a.k.a LA-LTE, LAA)

In a recent event in London called 5G Huddle, Alcatel-Lucent presented their views on what 4.5G would mean. If you look at the slide above, it is quite a detailed view of what this intermediate step before 5G would be. Some tweets related to this discussion from 5G Huddle as follows:

Good points: 4.5G as necessary step: CA, VoLTE & WebRTC, CoMP & coordination, NFV & cloud. But that can do everything we need #5GHuddle
— Real Wireless (@real_wireless) September 23, 2014

So 5G will be evolution of 4.5G using DC & CA - but much better signalling, more energy efficient as new air interface for IoT
— Real Wireless (@real_wireless) September 23, 2014

Finally, in a recent GSMA event, Huawei used the term 4.5G to set out their vision and also propose a time-frame as follows:

While in Alcatel-Lucent slide, I could visualise 4.5G as our vision of LTE(-A) + WiFi + some more stuff, I am finding it difficult to visualise all the changes being proposed by Huawei. How are we going to see the peak rate of 10Gbps for example?

I have to mention that I have had companies that have told me that their vision of 5G is M2M and D2D so Huawei is is not very far from reality here.

We should keep in mind that this 4G, 4.5G and 5G are the terms we use to make the end users aware of what new cellular technology could do for them. Most of these people understand simple terms like speeds and latency. We may want to be careful what we tell them as we do not want to make things confusing, complicated and make false promises and not deliver on them.

xoxoxo Added on 2nd January 2015 oxoxox

Chinese vendor ZTE has said it plans to launch a ‘pre-5G’ testing base station in 2015, commercial use of which will be possible in 2016, following tests and adjustment. Here is what they think pre-5G means:

'Real' Full Duplex (or No Division Duplex - NDD?)

We all know about the two type of transmission schemes which are FDD and TDD. Normally, this FDD and TDD schemes are known as full duplex schemes. Some people will argue that TDD is actually half-duplex but what TDD does is that it emulates a full duplex communication over a half duplex communication link. There is also a half-duplex FDD, which is a very interesting technology and defined for LTE, but not used. See here for details.

One of the technologies being proposed for 5G is referred to as Full Duplex. Here, the transmitter and the receiver both transmit and receive at the same frequency. Due to some very clever signal processing, the interference can be cancelled out. An interesting presentation from Kumu networks is embedded below:

Full Duplex Radios in 5G from Zahid Ghadialy

The biggest challenge is self-interference cancellation because the transmitter and receiver are using the same spectrum and will cause interference to each other. There have been major advances in the self-interference cancellation techniques which could be seen in the Interdigital presentation embedded below:

Potential of Full Duplex for Future Wireless Systems from Zahid Ghadialy

A quick update on Antennas

There were couple of very interesting and useful presentations from the LTE World Summit 2014 that I have been thinking for a while to embed in the blog. The first is a market overview from Signals Research Group. The research is focussed more on the US market but it has some very interesting insights. The slideset is embedded below:

Antenna Market Overview - Signals Research Group - June 2014 from Zahid Ghadialy

The other presentation is from Commscope on Base Station Antennas (BSA) for capacity improvement. I really liked the simplicity of the diagrams. Anyone interested in studying more indepth on the antennas are encouraged to check out my old post here. The complete slideset is below:

Commscope: Antennas Solutions for Capacity Improvement - June 2014 from Zahid Ghadialy

Envelope Tracking for improving PA efficiency of mobile devices

I am sure many people would have heard of ET (Envelope Tracking) by now. Its a technology that can help reduce the power consumption by our mobile devices. Less power consumption means longer battery life, especially with all these new features coming in the LTE-A devices.

As the slide says, there are already 12 phones launched with this technology, the most high profile being iPhone 6/6 Plus. Here is a brilliant presentation from Nujira on this topic:

Envelope Tracking : Fuel injection for the RF Front End from Zahid Ghadialy

For people who are interested in testing this feature may want to check this Rohde&Schwarz presentation here.

Elevation Beamforming / Full-Dimension MIMO

Four major Release-13 projects have been approved now that Release-12 is coming to a conclusion. One of them is Full dimension MIMO. From the 3GPP website:

Leveraging the work on 3D channel modeling completed in Release 12, 3GPP RAN will now study the necessary changes to enable elevation beamforming and high-order MIMO systems. Beamforming and MIMO have been identified as key technologies to address the future capacity demand. But so far 3GPP specified support for these features mostly considers one-dimensional antenna arrays that exploit the azimuth dimension. So, to further improve LTE spectral efficiency it is quite natural to now study two-dimensional antenna arrays that can also exploit the vertical dimension.

Also, while the standard currently supports MIMO systems with up to 8 antenna ports, the new study will look into high-order MIMO systems with up to 64 antenna ports at the eNB, to become more relevant with the use of higher frequencies in the future.

Details of the Study Item can be found in RP-141644.

There was also an interesting post by Eiko Seidel in the 5G standards group:

The idea is to introduce carrier and UE specific tilt/beam forming with variable beam widths. Improved link budget and reduced intra- and inter-cell interference might translate into higher data rates or increased coverage at cell edge. This might go hand in hand with an extensive use of spatial multiplexing that might require enhancements to today’s MU-MIMO schemes. Furthermore in active antenna array systems (AAS) the power amplifiers become part of the antenna further improving the link budget due to the missing feeder loss. Besides a potentially simplified installation the use of many low power elements might also reduce the overall power consumption. 

At higher frequencies the antenna elements can miniaturized and their number can be increased. In LTE this might be limited to 16, 32 or 64 elements while for 5G with higher frequency bands this might allow for “massive MIMO”. 

WG: Primary RAN1 (RP-141644) 
started 06/2014 (RAN#64), completion date 06/2015 (RAN#68)
work item might follow the study with target 12/2015 (RAN#70) 

Supporting companies
Samsung/NSN, all major vendors and operators 

Based on RAN1 Rel.12 Study Item on 3D channel model (TR36.873) 

Objectives 
Phase 1: antenna configurations and evaluation scenarios Rel.12 performance evaluation with 3D channel model 

Phase 2: study and simulate FD-MIMO enhancement identify and evaluate techniques, analyze specification impact performance evaluation for 16, 32, 64 antenna elements enhancements for SU-/MU-MIMO (incl. higher dimension MU-MIMO) (keep the maximum number of layer per UE unchanged to 8)

An old presentation from Samsung is embedded below that will provide more insight into this technology:

Full Dimension MIMO and Beamforming Technologies for B4G from Zahid Ghadialy

Related post:

• 3D-Beamforming and 3D-MIMO

NFV and 5G compatibility issues

There was an interesting discussion on Twitter that has been storified by Keith Dyer. Lets start by having a quick look at the C-RAN architecture that features in the discussion.

There are couple of excellent C-RAN presentations for anyone interested. This one by EE (with 9K+ views) and this from Orange (with 19K+ views).

Anyway, here is the story:

For anyone interested in exploring the discussion further, The Mobile Network has a more detailed comments here.

There are also an interesting article worth reading:

• Clouding the Edge for LTE-A and Beyond
• 5G Will Give Operators Massive Headaches – Bell Labs

Update on Public Safety and Mission Critical communications

Its been a while since I wrote about Public Safety and Mission Critical communications, so here is a quick summary.

Iain Sharp have a good overview of whats happening in the standards in the LTE World Summit back in June. Embedded below is his complete presentation.

LTE Standards for Public Safety – an independent analysis from Zahid Ghadialy

There is another slightly older presentation that I also thought was worthwhile adding here.

There is a lot of discussion centred around the use of commercial networks for mission critical communications, mainly die to cost. While this may make sense to an extent, there should be procedures put in place to give priority to public safety in case of emergency.

Tech Trend for Next Generation Critical Communications from Zahid Ghadialy

We are planning to run a one day training in Jan 2015 on public safety. If this is of interest to you then please get in touch with me for more details.

x-o-x-o-x-o-x-o-x-o-x-o-x
After the post someone brought these links to my attention so I am adding them below:

• Mission-Critical PTT Set for LTE Release 13, Release 12 Freeze Likely in 2015
• 3GPP News: LTE Mission Critical Applications
• 3GPP News: Delivering Public Safety Communications with LTE
• 3GPP SA6 - Mission-critical applications
• 3GPP-OMA-ETSI Critical Communications Workshop, August 26-27, 2014

LTE Device-to-device (D2D) Use Cases

Device-to-device is a popular topic. I wrote a post, back in March on LTE-Radar (another name) which has already had 10K+ views. Another post in Jan, last year has had over 13K views. In the LTE World Summit, Thomas Henze from Deutsche Telekom AG presented some use cases of 'proximity services via LTE device broadcast'

While there are some interesting use cases in his presentation (embedded below), I am not sure that they will necessarily achieve success overnight. While it would be great to have a standardised solution for applications that rely on proximity services, the apps have already come up with their own solutions in the meantime.



The dating app Tinder, for example, finds a date near where you are. It relies on GPS and I agree that some people would say that GPS consumes more power but its already available today.



Another example is "Nearby Friends" from Facebook that allows to find your friends if they are nearby, perfect for a day when you have nothing better to do.

With an App, I can be sure that my location is being shared only for one App. With a standardised solution, all my Apps have info about location that I may not necessarily want. There are pros and cons, not sure which will win here.

Anyway, the complete presentation is embedded below:

Enabling proximity services via LTE device broadcast from Zahid Ghadialy

For anyone interested in going a bit more in detail about D2D, please check this excellent article by Dr. Alastair Bryon, titled "Opportunities and threats from LTE Device-to-Device (D2D) communication"

Do let me know what you think about the use cases.

Wireless Charging: A must-have technology with maturing standards

Wireless charging has been in news recently with the discovery that Apple has found a brilliant way to wireless charge iPhones, iPads and iWatches. While we continue to wait for the details of that one, I thought its worth providing a bit of round up from the LTE World Summit not so long back. A summary of market by IHS is embedded as follows:

Qi (pronounced Chee), probably the most well known standard, not just because its already available in devices like Google Nexus 5 phone and Nexus 7 tablet  but also because its 1.2 standard allows devices to be charged from some distance away. They had an excellent presentation outlining their progress and technology as follows:

Finally, any discussion on Wireless Charging wont be complete without the mention of other big player, Alliance For Wireless Power (A4WP). The above shows a comparison between different standards and the presentation from A4WP is as follows:

Finally, if you haven't seen our concept of futuristic 'Smart Batteries' (crossed 10K+ views) then check it out here.

New LTE-A UE Category 9 and 10 in Rel-11

Its been a while since we saw any new UE categories coming but then I noticed some new categories came earlier this year for Release-11. The latest 3TPP TS 36.306 have these new Category 9 and Category 10 as follows.

For those who are aware of the categories of the UE's being used in practice may be aware that the most common ones have been 'Category 3' with 100Mbps max in DL and 50Mbps max in UL. The new 'Cat. 4' devices are becoming more common as more manufacturers start bringing these devices to the market. They support 150Mbps max in DL and 50Mbps max in UL. Neither of them supports Carrier Aggregation.

Having said that, a lot of Cat. 4 devices that we may use in testing actually supports carrier aggregation. The next most popular devices soon to be hitting the market is Cat. 6 UE's with 300Mbps max in DL and 50Mbps max in UL. Category 6 UE's support 2 x 20MHz CA in downlink hence you can say that they can combine 2 x Cat. 4 UE's in DL but they do not support CA in uplink hence the UL part remains the same as Cat. 4 device.

Cat. 9 and 10 are interesting case as Car. 8 was already defined earlier to meet IMT-A requirement as shown below.

To meet IMT-A requirements of peak data rates of 1Gbps in UL and DL, LTE-A had to define category 8 with 5 band CA and 8x8 MIMO to be able to provide 3Gbps max in DL and 1.5Gbps max in UL. No one sees this device becoming a reality in the short term.

The new categories will have to be defined from Cat. 9 onwards.

Cat. 9 allows 3 x Cat. 4 device CA in the downlink to have the maximum possible downlink data rates of 450Mbps but there is no CA in the uplink. As a result, the UL is still 50Mbps max. Cat. 10 allows carrier aggregation in the uplink for upto 2 bands which would result in 100Mbps max in UL.

The LG space website gives a better representation of the same information above which is shown below:

A UE category 9 transmits Rel 11 category 9 + Rel 10 category 6 + Rel 8 category 4

With Release-12 due to be finalised later in the year, we may see new UE categories being defined further.