Top 5 posts for 2014

Here are the top 5 posts from this year:

1. Dual-connectivity, Bearer split and other Release-12 small cell enhancements - Jan 2014
2. Unlicensed LTE (LTE-U) for Small Cells - May 2014
3. Small Cells Research Bible - April 2014
4. Wi-Fi Evolution and its Role in 5G Networks - September 2014
5. Dynamic Spectrum Access (DSA) techniques for Small Cells and Wi-Fi - May 2014

Small Cells Network Sharing

Network sharing makes sense for the operators in this day and age when ARPU keeps going down and users expect more from their networks. The picture above shows the different components that can be shared to increase the cost savings.

Small cells sharing has been on agenda for a long time and it is starting to be deployed in the networks. I an interview with the new Small Cell Forum chariman, Alan Law, ThinkSmallCell covered this as a question:

What's your view on multi-operator Small Cell solutions?

Historically, there were a number of factors holding back adoption of multi-operator Small Cells, ranging from commercial aspects to technical aspects such as managing how the available capacity is shared between operators.

However, two 3GPP standards (MORAN and MOCN) have been defined which allow the same Small Cells to be shared between networks.

A few vendors and operators have implemented these features today demonstrating that there is no reason why Small Cells must be tied to a single operator

In another article featuring Radisys:

Can't Small Cells support multi-operator without DAS?

There are two existing 3GPP standards which do make this technically feasible. Both are already in commercial use today.
MOCN (Multiple Operator Core Network) is a network sharing concept that is fairly straightforward to implement, similar to network roaming. MORAN (Multiple Operator Radio Access Network) is more involved, providing a deeper integration and requiring more software within the small cells.

Some of our key customers are already using MOCN, but I see MORAN being the long term future – sharing the RAN as an end-to-end resource rather than just connecting through the core network. I can see a major challenge as we move outdoors to the streets where practical deployment constraints won't allow multiple small cells to be strung from the same lamp-posts.

I covered this RAN sharing in the 3G4G blog earlier here.

While the above picture is for the UMTS network, the LTE network sharing would be similar. Embedded below is a research paper that discusses the various approaches and to small cells network sharing and also features some case studies.

Shared Smallcell Networks from Zahid Ghadialy

Here are some additional links on this topic that would make an interesting reading:

• 3GPP Network Sharing Enhancements for LTE - Unwired Insight
• Active RAN sharing business models can bring benefits to towercos as well as operators - Analysis Mason
• LTE Network Sharing - Alcatel Lucent
• BIPT guidelines for infrastructure sharing
• Active RAN Sharing - NEC
• Case Study: RAN Sharing in Poland

Small Cells and WiFi Forecast 2013 - 2019

We had this last set of forecasts back in February, here is a new one up to 2019/20.

The slides and the video is embedded below but I want to mention few things here. The first being that in the last year (or since the beginning of this year) the main change that has occurred is the availability of Voice over WiFi (VoWiFi), either as native or as an app, has become a commonplace. What this means that some small cells deployments are no longer high priority and has been pushed back.

On the other hand some operators are conscious that small cells can provide a better QoS than WiFi hence they are going ahead with Small cells deployments.

Anyway, Slides and Video as follows:

Please feel free to leave your opinions in the comments below.

'Inside-out' or 'Outside-in'

Going through my old presentations, I came across this prestigious lecture delivered by Dr. Tim Whitley of BT. The main argument of that lecture was, The future of mobile is fixed and the future of fixed is mobile. During the ending of the presentation there is a discussion on Outside-in v/s Inside-out. Lets look at those slides here:

The Future of Mobile is …Fixed from Zahid Ghadialy

Qualcomm is a big fan on Inside-out as can be seen here. Other small cell manufacturers support the inside-out approach too.

The question is, does inside-out approach matters any more. By next year many operators and devices will support VoWiFi in native client. Which means that even if your coverage is poor or non-existant inside, you will still receive voice calls and text messages. Data will continue over WiFi as normal.

An argument in favour of cellular is better/guaranteed QoS as in VoLTE and maybe new services can be available faster but private WiFi best (or no) effort is not bad generally.

What are your thoughts on this topic?

Connectivity in the stadiums

I have recently been observing a lots of discussions around connectivity in the stadiums. I have used this picture above a few times to show different solutions available in different situations. You can see that in theory Wi-Fi, DAS, Micro and Pico would all be suitable for the connectivity in stadiums. In practice this is generally limited to DAS and Wi-Fi.

ThinkSmallCell have recently written an article on the stadium Wi-Fi experience of The Cloud here. Some very interesting choices were taken to keep things simple:

For the main stadium bowl, The Cloud designed for 50% concurrent access for the maximum 30,000 crowd, connecting 80 Wi-Fi access points using 1km of fibre and 9km of CAT6 ethernet cable.

Each access point can handle up to 250 concurrent users. Tightly focussed beams were used to segregate seating blocks, splitting these into distinct coverage sectors.

To simplify the design, the older 802.11b standard wasn't used/supported, VoIP was blocked and a maximum of 3 SSIDs assigned. Unlike a cellular system, there's no handoff as you move around the stadium – you'd need to reconnect and create another session. During peak usage, almost everyone is sitting down rather than moving about (if you ignore those jumping up and down on their seats).

Both Wi-Fi spectrum bands at 2.4GHz and 5GHz were used, with devices capable of the higher frequency prioritised to use it. 56% of clients used the 5GHz band, which has much more spectrum and many more channels available. The different propagation characteristics mean there are different coverage footprints, so planners are actually designing two networks rather than one.

The side lobes on the 5GHz coverage footprint were massive, limiting the number of Wi-Fi access points that could be deployed.

You can read the complete article on the ThinkSmallCell website here.

A question some people often ask is why bother with connectivity in the stadiums. There are many reasons and personally, I would rather have connectivity than don't, even if I am not going to use it.

Real Wireless has done substantial amount of work in this area and a slide from their recent presentation discusses the benefits for various parties very well. You can read their opinion on this topic on their website here.

No discussion on Stadium connectivity would be complete without mentioning the US operator AT&T. They regularly publish statistics and details of connectivity in various sports venues on their website here. A recent report from their new site on DAS connectivity in various stadiums as follows:

• So far this season, there have been 119 pro football games and 214 college football games played across more than 75 different venues where we provide in-venue coverage via Distributed Antenna Systems (DAS). 
• In total, across these 333 games our customers have used more than 104.9 Terabytes of mobile data on our in-venue cellular networks. That’s the same as 104,913 Gigabytes. Or more simply put, it is equivalent to more than 300M social media posts with photos. 
• At this point in the year, pro football fans are edging college fans in average data usage per game by a 342GB to 293GB margin. Or a difference equivalent to about 140K more social media posts with photos per game on average.

Another recent report from the AT&T part in San Francisco where both Wi-Fi and DAS are present as follows:

Here are some of the record-breaking numbers we saw on our venue-specific mobile network at AT&T Park from the Giants’ three home games during the World Series:

• Fans used more than 477GB of data on the AT&T cellular network during the game on 10/25. This is equivalent to more than 1.36M social media post with photos.
  • This marked the highest single game total for cellular data usage at AT&T Park in ballpark history.

• Fans used an average of approximately 447GB of data per game over the weekend on the AT&T cellular network. This is equivalent to more than 1.27M social media post with photos.
  • It’s an increase of approximately 29% in cellular data usage compared to the average game during the League Championship series vs. St. Louis.
  • It’s an increase of approximately 109% in cellular data usage compared to the average game during the final home series of the regular season vs. San Diego (9/25-9/28).
• The peak hour of data usage during three home games was on 10/25 was from 5-6pm PT, the hour in which the first pitch occurred. In this hour more than 83GB of data crossed our venue-specific cellular network.

• On our AT&T Wi-Fi network we saw more than 1,626GB of data move across our network during the game on 10/25.
  • This is the highest single game Wi-Fi total in the history of AT&T Park.
  • 1,626GB is equivalent to more than 4.65M social media post with photos.
  • This showed an increase in Wi-Fi usage of approximately 302% compared to the average game during the 2012 World Series.
  • This showed an increase in Wi-Fi usage of approximately 163% compared to the average 2014 regular season game at AT&T Park.
  • This showed an increase in Wi-Fi usage of approximately 29% compared to the average game of the League Championship series vs. St. Louis.

• The collective data usage equaled approximately 2.1TB of data across both our cellular and Wi-Fi networks at AT&T Park during the game on 10/25.
  • This marked the highest single game total for collective data usage (cellular and Wi-Fi) in AT&T Park history.
  • 2.1TB is equivalent to more than 6M social media post with photos.

Note: All cellular data is specific to only AT&T customers using the DAS network at AT&T Park.

AT&T DAS guru Paula Doublin was one of the most memorable speakers at this year’s HetNet Expo. The company’s AVP for antenna solutions, DAS and small cells did not shy away from questions about AT&T’s budget for heterogeneous networks, nor did she sugar coat the outlook for small cell deployments. A video of her presentation is embedded below and a writeup is available on RCR Wireless website here.




See Also:

• Case Study: Deployment scenarios with DAS, RRH, Small Cells and Wi-Fi
• HetNet Strategies with Oi Brazil

Small Cells and/or WiFi - The confusion continues...

Its been an interesting last few weeks. Depending on which report you read, you will either come to the conclusion that 'WiFi will be killing off Small Cells' or 'Small Cells will be killing off WiFi'

First there was this report that "You might not need a mobile carrier by 2020". It makes this bold statement: In Europe, many cell phone owners have already ditched their wireless carrier. But Wi-Fi isn't quite widespread or robust enough for most Americans to completely ditch their wireless carrier just yet. In all honesty, I have never come across anyone that has ditched their mobile network operator and now relies entirely on Wi-Fi. I certainly know of people who now don't even bother switching on their WiFi because their cellular coverage is extremely good and have flat pricing.

Joe Madden, a respected analyst of small cells, recently said the following: "Even if we exclude homespot deployments, the number of Wi-Fi access points will reach the level of millions for cable operators and public venues during 2015, outstripping the capacity of new LTE base stations. Several large mobile operators have made a gigantic blunder, by ignoring the opportunity to deploy Wi-Fi or utilize Hotspot 2.0 –so cable operators and other service providers are jumping on the opportunity. Homespots add another dimension, with massive crowdsourcing of capacity. The total Wi-Fi capacity deployed by service providers worldwide could match the 'data tsunami' in terms of raw capacity over the next five years, although of course there are obvious limitations in mobility and QoS."

While you may be thinking Wi-Fi '1' and Small Cells '0' a thing to remember is that WiFi still has some way to go to sort out the security stuff. This article highlights how easy it is spoof a WiFi AP, the one you have trusted in the past and easily access personal Info. I strongly suggest that you read this article. One may argue that some of these issues will be gone with HS2.0 and other new security mechanisms these problems will vanish. One has to remember though that since WiFi uses unlicensed bands, and since the technology has been around for ages, its easy to get cheap equipment and it may not exactly be illegal to have equipment running in this band.

Cellular on the other hand relies on licensed spectrum and has a very strong authentication mechanism which may get around such basic insecurity info (though to some extent this can be hacked, depending on operator policies on the UICC/SIM card).

Dr. Kim Larsen, recently did a presentation where he looked at the economics of Small Cell and WiFi and in what situations both of these make sense. His presentation is embedded below.

Some thoughts from Kim on his presentation on Twitter:

• Most Smartphone based WiFi traffic happens at Home, believing this traffic is offloaded is rather foolish!
• WiFi...Why & When to care (at least when you are an mobile operator)
• Why do we like WiFi so much & why cellular have so many challenges matching consumer expectations!
• WiFi has the consumer perception of being 1 Fast, 2 Almost Free & 3 Unlimited...Brilliant Branding!
• Mobile Operator WiFi off-loading strategies should consider mitigating potential & substantial cellular revenue loss!
• When WiFi makes the most sense for a Mobile Operator; 
1. Cellular expansion options have been exhausted!
2. you control fixed & mobile sides of the customer experience & value chain! 
3. Competitive Pressures .. ultimately is likely to be a loss-loss scenario!

Dynamics of Change, panel discussion from #HetNet2014

A good panel discussion video from HetNet2014 conference. I think the image above would be useful for someone wanting a quick recap of the different types of small cells.

Barry McLaren of Ericsson, John Bramfeld of Advanced RF Technologies, Asad Vaince of Boingo Wireless, Mark Reynolds of the University of New Mexico and Jeffrey Funderburg of AT&T   talk rapid changes in the mobile broadband industry at the HetNet Expo 2014 (#HetNet2014).

Technology changes in the mobile broadband space are happening more rapidly than ever. Wireless service providers are rolling out LTE, with Advanced LTE and Voiceover LTE on the horizon. In parallel, 802.11a/c is being added to the Wi-Fi technology mix and Passpoint-certified devices could be game changers. This panel explores the perspectives from the wireless service provider, original equipment manufacturer, neutral-host provider, systems integrator and end user on how they are adapting—and getting ahead of—the rapid pace of change in the industry.

Questions discussed:

• How does the latest upgrades impact what you do?
• What do you envision 5G to be and will we realisitically see it?
• Is 5G going to get rid of the problems thats keeping you awake in the night. Is it going to make things simpler?
• How is HS2.0 and Passpoint, helping WiFi rollout and offloading?
• Are the advances in WiFi going to make Small Cells irrelevant or are they going to work together?
• What does the migration path look like for a move from CS Fallback to VoLTE with limited handsets available?
• Is there a quality issue with VoWiFi?

Non-ideal backhaul for Small Cells

Recently I came across this Linkedin discussion on What is "non-ideal backhaul" so I thought it may be worth adding it to the blog. The simplest of explanation can be seen from the picture above that is extracted from 3GPP TR 36.932.

An ideal backhaul is defined as latency less than 2.5 microseconds and a throughput of upto 10Gbps. All other types of backhaul is non-ideal.

Another way of putting this is: If you look at the Release 12 study and technical report on Small Cell Enhancements, it is regarded as a backhaul that cannot carry a RRH to eNodeB link, which in turn has been interpreted as not meeting CPRI round trip and bandwidth requirements (via Kit Kilgour)

If you know anything additional, please feel free to add it in comments.

In-building Wireless Solutions Webinar

Last month, David Chambers from ThinkSmallCell held a webinar exploring available In-building solutions and comparing the advantages and disadvantages of each solution, also looking at the approach taken by different vendors. Worth a look. The presentation and Youtube video are both embedded below.

Small Cells Equipment Magic Quadrant, by Gartner

This post has been removed on request by Gartner.

Small Cells: Interoperability and Plugfests for Multi-vendor HetNet's

Our recent Small Cells SIG in Cambridge Wireless was another full house with the topic under discussion being Small Cells Deployment: Whats the hold-up. One of the areas being tackled by Small Cell Forum is to have plugfests to identify the issues that are causing hold ups and fix them. There were two interesting presentations with interesting take on this topic. The first was by Neeraj Gupta and Kreso Bilan of NEC who are both very active in this interoperability and plugfests. Their presentation which doesnt need any explanation is embedded below:

Multi Vendor HetNet: Interoperability, Plugfests from Zahid Ghadialy

The other presentation was by Nick Johnson of IP.Access who listed the problems and the source of the problems that gave rise to the interoperability issues and also gave a quick summary of what the plugfests achieved (see picture above). His slides are embedded below:

Small Cell Interoperability in the RAN from Zahid Ghadialy

The conclusion of the event was that there are no issues or reasons for these hold-ups. The operators have been over cautious and preferred to play a waiting game but are now getting confidence and starting to deploy small cells. Some minor issues in interoperability revolves around X2 interface and SON but they should get ironed out in the couple plugfests planned for next year (see NEC slides).

HetNet Strategies with Oi Brazil

Brazil has been in limelight since the beginning of the year. Initially, the focus was on how the FIFA World Cup may fail but later on for the way everything came together at the last minute and everything worked. From a technology point of view, WiFi was a big saviour in the stadiums, allowing good connectivity for everyone wishing to add the things they liked on social networks as soon as they can.

An example was this chart tweeted by Ruckus Wireless to proudly show what their achievement was with stadium WiFi.

Recently, Maravedis-rethink conducted a webinar with the Brazilian operator Oi, regarding their HetNet strategies. The video for the relevant part is embedded in the end. Two slides caught my attention. The first was about the different technologies and their concerns (above). For example for a HetNet to be successful, all components should synchronised and have a strict time accuracy requirements. The Backhaul & Fronthaul requirements are equally interesting for different cases.

The second interesting slide is the final one where they have their wish list to what they would like to do in near-term and long-term. WiFi features in all the scenarios except for the rural case (as expected). Anyway, here is the video:



You can download the slides from Slideshare here.

Airvana's OneCell™ with C-RAN and Super-cell

Airvana recently announced its OneCell™ system was named the winner in the “In-Building Wireless – Small Cell, Wi-Fi, LAN” category of CTIA’s annual Emerging Technology (E-Tech) Awards competition. I remember back in June, it received a lot of praise for this product. So what exactly is so unique in this OneCell™.

From their press release back in June:

Based on cloud RAN principles, the OneCell system consists of a Baseband Controller and multiple Radio Points. Together they form a single "super" cell that delivers consistently high quality LTE service across indoor spaces ranging from 50,000 to 1,000,000 square feet without handovers or inter-cell interference issues. OneCell supports plug-and-play deployment over standard Ethernet cabling and switches, eliminating the need for proprietary networks or expensive optical links. Further, its unique small cell cloud RAN architecture dramatically simplifies radio frequency planning and integration with wireless macro networks.

There is a mention of C-RAN (though I have had discussion where this claims have been disputed), Super-cell and is pitched towards enterprises.

Airvana's website has a good picture explaining how a super-cell gets rid of interference on cell edges as all the cells work together as a single large cell.

In fact the scheduler can cleverly assign the same resource blocks to different users and hence increase capacity.

Below is a video explaining their solution in more details:

Wi-Fi Evolution and its Role in 5G Networks

Picture Source: EE Times Asia

'5G' is becoming a  very popular term. Every other day there is some sort of a press release about some company working on a 5G technology. Those who follow my blogs will nevertheless know that I think there will be an intermediate stage which we term as 4.5G where Wi-Fi and Cellular will work together, in harmony.

While the Release-12 of 3GPP standards have been focussing on many areas, the headline grabbing technology has been Carrier Aggregation (CA). 3 bands CA in the downlink and 2 band CA in the uplink is expected to become a norm. New UE categories 9 and 10 have been defined for this.

While 802.11n, 802.11ac and 802.11ad is now starting to gain popularity, discussion about the next generation of Wi-Fi standards, 802.11ax has just begun.

I recently came across an interesting presentation from Ericsson on this topic and I think it may be worth watching. The presentation is available here and video of the presentation is embedded below:


There are lots of other talks and presentations from the Johannesberg Summit 2014 that is available here.

Case Study: Deployment scenarios with DAS, RRH, Small Cells and Wi-Fi

I attended an interesting webinar (details in the end) from Infonetics Research, EXFO and ExteNet Systems where one of the areas of discussion was around which technology for which scenario. The four main technologies being considered was DAS, RRH, Small Cells and Wi-Fi. There was some interesting deployment examples that I have embedded below:

How to Get the Best Out of DAS, Small Cells, and WiFi from Zahid Ghadialy

NOTE: If the slides are not working, please view it on Slideshare - slides 21 to 24

To watch the webinar recording and download slides, please follow this link: http://w.on24.com/r.htm?e=783410&s=1&k=CD70E2F6D98C3E67A3B5A1936E23DB13

New types of HetNet's Cell coordination

Came across this HetNet Infographic from Ericsson here. They are proposing something interesting as can be seen in the picture above. From the infographic:

Macro for downlink, micro for uplink
In the imbalance area, the downlink signal from the macro is the strongest, because it transmits at a much higher power, whereas the uplink signal from the pico node is much stronger, because it is closer. This provides the user with significantly higher uplink speeds than would be possible with macro coverage alone.

So if we have a macro with an overlay of small cells then the Macro can be used for DL and Small Cells for UL. This scheme is a counterintuitive to what I would have thought. Since there is a higher requirement in DL as opposed to UL, the uplink could be received by Macro and the DL could be sent from pico node. The macro also has bigger antennas and can process weak signals from the UE.



Ericsson and the South Korean operator, SK Telecom recently also demonstrated 'Elastic Cell'. As per Telecom TV:

The telco has confirmed that Elastic Cell technology is based on the 3GPP Release 11 CoMP specification, but with improved scheduling, energy efficiency, and cost efficiency. SK Telecom says it has applied downlink CoMP since early 2012 and uplink CoMP in April 2014, and both technologies are proprietary technology. Because coordination between networks will still be very important in 5G technologies, SK Telecom expects that Elastic Cell will become a key enabler for 5G.

Another similar approach that is proposed by NTT Docomo is the 'Phantom Cell' concept as described here. Their proposal is to separate control and user planes. Macro used for signalling (C-plane) and Small cells in higher frequencies for data (U-plane)

Finally, we also have the SK Telecom's SUPER Cell concept and blogged here. There is a lot of cell splitting in this but again we have the main frequency (lower) being able to do both control and data while the higher frequency is only to do data. Sounds a bit like the Phantom Cell and 'New Carrier Type' as blogged here before.

Are there any other types of cell coordination being discussed. Do you have any opinion on them? Feel free to add comments.

Wi-Fi and Cellular: Authentication & Security

While in the past WiFi was considered not as secure as the cellular counterpart, things have been changing slowly and steadily. While the cellular is able to offer authentication using the EPS-AKA, Wi-Fi is now able to offer EAP-AKA and EAP-SIM. 

In fact the above table is quite interesting to know about. Recently I was following a discussion that talked about the lack of QoS support in WiFi. As we can see, its supported but not guaranteed. 

Devices that contain the USIM card can use EAP-AKA while that without one can offer EAP-SIM. EAP-AKA works in a similar way to the cellular authentication protocol EPS-AKA. For anyone who is interested in reading more details about the authentication and how it works, including signalling, see this whitepaper here.

If you haven't seen our whitepaper on Cellular and WiFi integration, please check it out here.

SDN and Distributed NFV for Small Cell Mobile Backhaul

An interesting presentation on how Distributed NFV can be used for Small Cell backhaul. The calculations show that 80% TCO savings. The presentation is embedded below and the video is available for viewing here.

Case Study: Fastback IBR Small Cell Backhaul Usage Scenarios

An interesting presentation from the recent Small Cells World Summit 2014 (kindly shared by Lance Hiley of Fastback Networks). The first part is a trial by Virgin Media and the later part is the case study by Fastback networks where they used their Intelligent Backhaul Radio and reduced the number links required to obtain similar performance as compared to a 'line of sight' solution. The presentation is embedded as follows

LOS, nLOS & NLOS: All-­In-­One Small Cell Backhaul For Cost-­Effective Delivery of SLAs from Zahid Ghadialy

Huawei's Lampsite

Huawei unveiled its 'Lampsite' for 'Deep Indoor Coverage' back in 2013. This is what they announced then:

LampSite includes a comprehensive set of BBU, RemoteHUB(rHUB) and PicoRRU(pRRU) products along with accompanying transmission solutions. The compact pRRU supports multiple bands and modes and can simultaneously support LTE TDD, LTE FDD, UMTS and GSM. A LampSite indoor coverage network can also be deployed simultaneously with Huawei’s SingleRAN solution. 

Thanks to BBU’s baseband sharing feature, one fiber is used for several cells, saving up to 87% of fiber typically used for indoor deployments. rHUB connects to pRRU by cable, and support power over Ethernet (PoE) to simplify site construction and reduce total deployment costs. 

In an early deployment phase, individual pRRU cells aggregate into one cell to reduce interference. Once the network offloads heavy traffic, the cells are split again and Adaptive SFN is enabled to balance capacity and interference. Huawei iManager system and evaluation tools are then used to accurately monitor and intelligently optimize indoor hotspot traffic.

This innovative solution has not only helped them to win contracts with China Unicom, TDC Denmark and Telenor Norway but according to TMN magazine article, "Huawei is shipping more than 10,000 PRRUs (Pico Remote Radio Units) per month in some countries and regions for its LampSite in-building system, according to Peter Zhou, Huawei's President of Small Cell & WiFi, Wireless Network."

Recently Huawei and Telenor also won an award in the LTE World Summit for "Innovation in HetNet Development". With Huawei’s LampSite, Telenor is able to provide average downlink throughput of 46Mbps at any location in a building and significantly cut costs. Deployment of each pico Remote Radio Unit takes only three hours – from site survey, through installation, commissioning, to going live, ensuring rapid rollout in areas with weak signal penetration.

Based on presentations in different events, looks like Huawei is not complacent with its achievements. It plans to develop the next generation or NG Lampsite to achieve 1Gbps Indoor throughput with whole lot of technologies to help achieve this. Multi-stream Aggregation (MSA) being the key. See my earlier post on MSA on the 3G4G blog here.


Related Posts:

• Telecoms Infrastructure Blog: Huawei Lampsite 3.0
• Telecoms Infrastructure Blog: Small Cells and Neutral Host Networks
• Telecoms Infrastructure Blog: Huawei SkySite: Drone with 5G base station & '5G Book' RRU

Tight, Tighter and Very Tight Integration between LTE and WiFi Networks

For those who are unfamiliar about the trusted and non-trusted access, I strongly recommend reading our whitepaper on Cellular and WiFi Integration here.

The standard and the most popular Integration approach between LTE and Wi-Fi is via the Trusted architecture as shown above.

There is a proposal for RAN level Integration which would result in Even Tighter Integration of WiFi

Now some researchers are proposing a Very Tight coupling between LTE and Wi-Fi which would mean that regardless of the access, the UE can be sent data from the same data stream over WiFi and LTE. Though this is radical, these approaches are already being thought about for '5G'. Whether it will happen in a future release of 4G or 4.5G remains to be seen. Here is the complete paper embedded below:

Very Tight Coupling between LTE and Wi-Fi for Advanced Offloading Procedures from Zahid Ghadialy

3GPP Definitions of Small Cells

While the Small Cell Forum defines the different types of Small cells clearly and these Small Cells can be said to contain the complete/partial functionality of the eNodeB, 3GPP definitions of Small Cells can be a bit fuzzy sometimes.

Generally, in the 3GPP documentation, there is a reference to Femtocells and Picocells. Femtocells are Small Cells that are defined as Closed Access (see my old post here) by 3GPP. The open access small cells are referred to as Picocells. Sometimes remote radio heads (RRH's) are also referred to as Small cells, open access type.

Relays, even though not referred to as Small Cells by 3GPP, is also referred to as Small Cells by some people.

Do you know of anything else?

Small Cells World Summit (#SCWS14) Video and Summary Articles

The Small Cells World Summit concluded last week. The main highlight was the Release 4 of Small Cell Forum on Urban, building on top of Release 3 - Urban foundations



Around 20 new documents have been published, available here on this release. Land Mobile has more details about this launch by Small Cell Forum here.

There were couple of interesting videos from the event by ThinkSmallCell and ConvergeDigest, they are embedded below:





Other related links (new links will be added as and when available):

• Airvana Is Back With a 'Cloud RAN' 4G Biz Cell - Light Reading
• Urban Jungle Is Still Too Wild for Small Cells - Light Reading
• Small Cell Forum Tackles Urban, Virtualization - Light Reading
• This is not the small cell you are looking for: why ip.access' presenceCell will make operators money by rejecting users - TMN Magazine
• Operators hoping for small cell "Sweet Spots" - Mobile Europe
• Mini cell towers: The end of crappy phone service - CNN
• SCWS: small cell sectors seeks diversity without fragmentation - Maravedis-Rethink
• Small Cells World Summit 2014 Event Report - ThinkSmallCell

X2: The necessity for Interoperability and Interference management in HetNets

Recently I wrote an article in the TMN magazine here about HetNet co-ordination. One important point that I mentioned here (and in several of the trainings that I do) is that X2 can be quite a useful interface, especially when you want to manage Interference between just macro cells or between different types of cells, as in HetNet environment. From the TMN article:

The initial deployments of LTE did not pay too much emphasis on X2 interface being present. Inter-operability was another issue for which X2 didn’t work very well. One of the major benefits of having an X2 interface is that different base stations or eNodeB’s (hereafter referred to as just eNB’s) can talk to each other and coordinate to make sure interference is kept at the minimum, especially on the cell edges. The Macro-cell’s had the provision for the X2 interface from the beginning, which formed the basis for Inter-Cell Interference Coordination (ICIC). Initially, the Small-cell’s didn’t have a facility for an X2 interface amongst them or with the Macro-cell. The support of X2 for Small-cell’s was added in 3GPP Release-10 and 3GPP Relese-11 (hereafter referred to as just Release-10 and Release-11) as seen in the picture. X2 for Small-cell’s is crucial for Interference management in HetNets.

The Small Cell Forum just published a whitepaper called "X2 interoperability in multi-vendor X2 HetNets". This paper is quite interesting with just the right amount of details. In their own words:

A key area of standardization needed to support small cells relates to the procedures to assist co-ordination with macrocells over LTE’s ‘X2’ interface. This document surveys standards currently in place to support frequency domain interference coordination,time domain interference coordination, mobility robustness and mobility load balancing. 

The whitepaper is available to download from here and is embedded below:

Small Cell Forum Release 4: X2 Interoperability from Zahid Ghadialy

The role of Small Cells, CoMP and Massive MIMO in 5G

Embedded below is a recent paper from IEEE Communications Magazine on the role of various techniques in 5G. The main focus is achieving higher spectral efficiency. From the paper: "From a high-level perspective, there are three main contributors to reaching higher spectral efficiency: advanced interference mitigation, small cells for densification of the network nodes, and massive multiple-input multiple-output (MIMO), that is, a significant increase in the number of antennas at the base station and potentially also at the terminal."

DAS or 'Small Cells' for Indoor Location

There was a recent webinar by Maravedis-Rethink & EJL. The slides are available on Slideshare here. I think there were some good points made about using DAS or Small Cells for the Indoor environment. Here is the youtube clip. You can drag the pointer to the beginning, to listen from the start.

Small Cells for the 'Connected Car'

Couple of weeks back I was in an event where Connected cars were a big focus. A few discussions centred around Small Cells in the cars. It may be a bit of a challenge but it should still be possible to have Small cells in the cars. The biggest challenge would be the backhaul. You cant have the standard backhaul for cars, especially as its moving, generally at high speeds. 

Some tricky solutions where one of the frequencies is used for backhauling small cells while small cells would provide coverage to the passengers of the car may be doable but it may not be worth the effort. 

Generally, the focus right now is to have something like a MiFi device in the car. The device can receive the mobile network signals and create a Wi-Fi hotspot.

Another solution being discussed was the use of Mobile Relay Node (MRN). As far as I understand, MRN has been pushed out of Release-12. Another issue is that the practical gain may not be as good as expected. Most of all, small cells or relay would only be useful if all the passengers in the vehicle reply on the same mobile network operator. As far as I have seen, this is generally not the case.

In light of this, it would make sense to continue on the current solution of having Wi-Fi hotspots in the cars backhauled to the mobile network.

Your thoughts please.

Unlicensed LTE (LTE-U) for Small Cells

I first wrote about LTE-U (or U-LTE as referred by others) back in December last year pointing towards the Qualcomm presentation here. As things move fast in our industry, quite a few things have happened in the last 6 months. Huawei did a demo of U-LTE in Mobile World Congress this year and LTE-U has been a constant topic of discussion in various 3GPP meetings. A half-day workshop is due to take place in June to discuss this topic further. In the meantime I have summarised some of the discussions that took place (unofficially?) in Jan 2014 between the interested parties.

To be clear, the discussions for LTE-U are centred on the 5GHz unlicensed spectrum. As you can see from the picture above, there is a massive amount of spectrum that is available, either free to use (unlicensed) or in a lightly licensed way.

There are strict rules and regulations in place to make sure this license is not misused or monopolised. There will be a need for Dynamic Spectrum Access (DSA) techniques that I have discussed here. The current LTE standards do not have a DSA inbuilt and hence referred to as "Rude". The following is from a recent Light Reading article.

The technical concern with LTE-U, as Peters describes it, is that LTE is a "rude" technology. WiFi includes a "politeness protocol" that LTE lacks, meaning that WiFi will back off if it senses interference from other users. Eventually rude ol' LTE operating in WiFi's polite bands could take over the band.

The 3GPP called another unofficial meeting in January to discuss concerns around LTE-U, which also included the potential effect on the value of licensed spectrum, the need for international harmonization of the unlicensed bands used for LTE-U, and whether the technology would be for downlink only or uplink as well. The group met again in March, primarily to work out timing for the new technology's deployment.

Huawei presentation explains why unlicensed carrier offloading, see the embedded presentation for details.

NTT Docomo shows the various deployment scenarios and also lists the regulatory aspects, especially in Japan. See the complete presentation below:

Nokia has even gone ahead and done simulations for different scenarios. The scenario above shows LTE deployment in the same unlicensed band as WLAN as you can see, the results are similar to the interference in WLAN-WLAN case.

There is also a roadmap to how LTE-U standardisation will work in 3GPP, hopefully after the workshop in June, we will probably hear more.

As expected, some of the operators with heavy investments in WiFi (like AT&T) have some reservations on LTE-U. Some analysts on the other hand are sceptical on how much savings there would be, taking the interference into account. Note that spectrum is just one part of deployment costs, there are many other factors to consider. Personally, I don't have an issue whether this will work or not, it definitely would do but with all the advancements in LTE-Wi-Fi Interworking, I think we may be able to do a better job with just selective deployment of LTE-U and using technologies like MAPCON, IFOM, Hotspot 2.0, etc.

Added on 9th July 2014

3GPP held their workshop on unlicensed LTE on 13/06/2014. See the news on 3GPP website here. All documents are available here.