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:

Optimising Small Cells Architectures for In-Building Solutions from Zahid Ghadialy

Small cell standardization in 3GPP Release 12

A presentation looking at Small Cell Standardisation in 3GPP Rel-12.

Small cell standardization in 3GPP Release 12 from Zahid Ghadialy

The story of Femtocells, Small Cells and Metrocells

Femtocells were introduced many years back as a residential, closed group, small base station. The intention was to provide coverage at home for high speed data (primary) and voice (secondary). It was more for coverage than capacity. In these good old days smart phones were far and few and feature phones were many. WiFi on the phone made it expensive and power hungry so cellular was the way to go.

There were many opportunities for Femtocells to take the centre stage as the concept is technologically sound but the operators have been not very willing to deploy it soon enough. Some operators were more willing to give it a try to fix their own issues, for example Softbank which gave free femtocells, in open access mode, to improve its coverage issues. Femtozone services that promised value addition provided with the Femtocells, never took off. Other promises of exclusive broadcast content using Femtocells for example never materialised due to lack of availability of the handsets and content.

Lot has changed since then. The smartphones and tablets have taken over the market, all of them have inbuilt WiFi that is generally more efficient than the cellular radio, coverage issues have become secondary and capacity issues are a bigger concern. Femtocell players have realised that except for the publicity, there isn't much to gain from the Femtocells. As a result Femtocells were replaced by the term Small cells that represents much more than the old Femtocells. The residential Femtocells have been reduced to being just voice boosters.

The different types of Small cells can be seen in the picture above. Except for the residential, the other types of small cells operate in either the open mode or the hybrid mode. Personally, I differentiate closed Femtocells from the other Small Cells. Metrocell is the upcoming type of Small cell that I believe everyone is focussing on. They operate always in the open mode and have been chosen as the promised one to solve the two major problems of capacity and coverage.

According to the Small Cell Forum introductory whitepaper, Metrocells would see an increased growth in the next few years when the operators start deploying more of them and less of the Macrocells.

So for those of you who don't know, and would like to learn more, an introductory presentation on Metrocells is available here.

If this is an area of interest and you are interested in having and in-depth understanding then we invite you to attend our Metrocells Masterclass which is a one day workshop explaining ins and outs of Metrocell. 

If you are a big organisation and would like us to provide you with a private workshop, please feel free to contact us for details.

We have also started the Metrocells Blog that I will use to post information related to Small Cells and Metrocells in future. Please feel free to take a look at: http://metrocells.blogspot.com/

'Small Cells' Analyst Forecasts

Interesting discussion, courtesy of Think Small Cell



If you just want to view the slides quickly, available below:

Small Cells 'Terminology' and 'Comparison'

Here is AT&T's attempt in comparing the small cells. The above comparison is probably based on the assumption that LTE Small cells are not yet widely available. Once they are, then LTE can be put in for most columns in the Technology part.

See also:

• Small Cells: Comparison and Deployment Scenarios - NSN

2 Presentations on Mobile technology Security

Present and future Standards for mobile internet and smart phone information security from Zahid Ghadialy

Other related posts:

• Evolution of 3GPP Security
• 'Mapped Security' Concept in LTE
• 3GPP LTE Security Aspects
• New Security Algorithms in Release-11
• 6th ETSI Security Workshop

"Small Cells" - An introduction for beginners

A good starting point for beginners on Small Cells:

 

Related links:

• Small Cells: Comparison and Deployment Scenarios
• Whats inside a Picocell?
• Building the World’s Largest Residential Small-Cell network
• ‘Small Cells’ and the City
• ‘Proximity Marketing’ and ‘Location Based Services’ (LBS) using ‘Small Cells’
• Radio Challenges and Opportunities for Large Scale Small Cell Deployments

Quick update on 3GPP Release-12 progress

Some months back, I blogged about the 3GPP Rel-12 workshop, since then there has been progress on the Rel-12 features. Here is a quick update from 3GPP:

Future 3GPP RAN standardization activities for LTE from Zahid Ghadialy

You can download the PPT from Slideshare.

Other related posts:

• Quick Introduction to LTE-Advanced

Hotspot 2.0, Next Generation Hotspot (NGH), etc.

From ZDNET:


Hotspot 2.0 is about certifying the hotspot itself, providing authentication using SIMs or certificates and the 802.11i standard, and using the recent 802.11u standard to provide performance and other information about the hotspots visible to a device. This will allow you to roam onto a hotspot with good connectivity that you have the right account to use, doing away with the need to select the network or enter your details into a web page, as you do today.

The Wi-Fi Alliance deals with the Wi-Fi hardware and the authentication specification under the name Passpoint, but this certification doesn't cover everything. The Wireless Broadband Alliance is a group of mobile and Wi-Fi operators that takes the Passpoint certification and ensures interoperability with other parts of the network — including authenticating to carriers' remote access RADIUS (Remote Authentication Dial-In User Service) servers, as well as roaming and billing.

"Next Generation Hotspot is the implementation of Hotspot 2.0 into a real, live network", explains Nigel Bird, the NGH Standardisation Manager at Orange Group.

From Next Generation Hotspot whitepaper:


A new program called Next Generation Hotspot (NGH) - using the latest HotSpot 2.0 specification1 - allows a mobile subscriber to connect automatically and securely to Hotspots using his service provider credentials while maintaining roaming visibility for the operator. NGH enables operators to continuously monitor and manage “cellular-like” service over Wi-Fi domestically and internationally so as to enhance performance and meet the demand for mobile data services over heterogeneous RANs - cellular and Wi-Fi. This enables mobile operators to simultaneously optimize backhaul throughput, offload specific traffic rapidly (e.g. video) and achieve better economics than traditional, cellular-only solutions.

The Wireless Broadband Appliance (WBA) and Small Cells Forum recently announced collaboration on this topic, see here.

More details are available in this presentation embedded below:

'LTE' and 'Small Cells' specific applications

Some 4 years back, I posted my first presentation here, titled "LTE Femtocells: Stepping stone for 'killer apps' presentation". I had couple of apps in mind that I thought could benefit from both LTE and Small Cells (or Femtocells to be specific).

The first was your phone acting as a Wireless Hard Disk Drive (HDD) that can be used to store things remotely in a server somewhere. This is similar to what is known as the Cloud nowadays.

Picture Source: Dialaphone.

The other day when I read why LTE is suitable for cloud connectivity, I could see that my old idea could start to become a reality. The article is here. Selective abstract as follows:

The LTE network lends itself well to cloud connectivity because it:

• provides high-bandwidth connections
• is IP- and Ethernet-oriented, the technologies used to connect to the cloud and within data centers
• offers tools that operators didn't have in 2G and 3G (such as more granular ability to manage traffic flows and a better, DPI-based view of traffic running on the network)
• features low latency, which is vital to the small flows and sessions that characterize M2M communications.

The rise of both cloud services and LTE creates a virtuous cycle. Cloud services continue to grow, which helps operators sustain their LTE business model. That growth enables them to accelerate LTE investments. Then operators can support new types of enterprise services, including cloud-based applications.

To take full advantage of this opportunity, operators have to deploy the right backhaul infrastructure. In addition to IP awareness and content awareness, the right backhaul network can leverage the technical advantages that LTE presents:

• flattened architecture that helps distribute compute and storage resources
• seamless migration from 2G and 3G for various physical mediums and networking protocols
• an increase in capacity that starts to put mobile connectivity on par with fixed broadband access.

My reasoning for Small Cell here is, in most cases when you are doing operations that require large amounts of data to be transferred, you will be indoors, either at home or in office or in a low mobility scenario. The requirement for high security and at the same time high speed data transfer that should not be affected by other users in the cell (capacity issues) can be easily solved by using a Small cell (Femtocell for indoors, Metrocell for outdoors).


The other application I had in mind was the Home Security System. I read the following on TotalTele the other day:

3UK's wholesale division on Friday detailed plans to capture high-margin machine-to-machine traffic by partnering with service providers that are likely to have higher-than-average bandwidth requirements.

As a 3G-only operator, the company cannot go after high volume, low margin M2M traffic because it typically only requires a 2G connection. However, there are opportunities to use its 3G network to address more data-hungry verticals that will generate higher traffic volumes.

"The margin on one CCTV M2M connection is more than 50 times bigger than the margin on a smart meter connection," claimed Tom Gardner, lead wholesale manager at 3UK, during Breakfast with Total Telecom in London.

"There is one CCTV camera for every 14 people in the U.K.," he said. "If I can put a SIM in every one of them I'll be a very happy man."

3UK, which on Thursday launched its Ericsson-based wholesale M2M platform, sees a big opportunity in CCTV, particularly for mobile and temporary installations at festivals, for instance. Other potentially lucrative sectors it has identified include digital signage, back-up for fixed Internet connections, and backhauling WiFi traffic from public transport.

I am sure some of you may be thinking that '3' UK uses HSPA network, not LTE, which is true. The point here is that it could be done better using LTE and Small Cells.

The reason for using LTE would be to provide higher data rates, meaning that information can be sent faster, with higher resolution and more regularly. This will help identify the problems earlier. If the CCTV is used indoors or in high usage areas, it would make sense that it connects via Small Cell to avoid creating capacity issues in the Macro network.

Here is the embed again, of my old presentation just in case if it interests you:

Lte Femtocells: Stepping stone for killer applications from Zahid Ghadialy

Small Cells: Comparison and Deployment Scenarios

From a presentation by NSN in the Small Cells Global congress.

Virgin Media's offering on SCaaS

I have blogged about FaaS in the past that is now undergoing trials. I also blogged about SCaaS from our last Cambridge Wireless event that shows the seperation between the operator and the services provided by Small Cell service provider. In the recent Small Cells Global congress, Kevin Baughan from Virgin Media gave an interesting talk on their recent trials. This is the architecture they are proposing.  

They would do site acquisition and maintenance, provide the backhaul and power, any mobile network operator (MNO) can come and put their small cell on the furniture to provide the coverage. I am not sure if multiple operators would pitch for the same sites but I wouldnt think of this as a problem as I am sure there would be multiple sites available in the same location.

A real killer from Virgin media could have been that it does something similar to Free, the French mobile operator that has apparently got Femtocells inbuilt in the set top boxes.

We will have to wait and see how many operators are willing to have third party host their small cells and how many.

‘Small Cells’ and the City

My presentation from the Small Cells Global Congress 2012. Please note that this presentation was prepared at a very short notice so may not be completely accurate. Comments more than welcome.

‘Proximity Marketing’ and ‘Location Based Services’ (LBS) using ‘Small Cells’

‘Proximity Marketing’ and ‘Location Based Services’ (LBS) using ‘Small Cells’ from Zahid Ghadialy

Quick summary of the 'Operator Mindshare' session from Small Cells Global Congress

We had quite a few interesting discussions in the Small Cells Global Congress, Operator Mindshare session. Here are some of the things that were discussed:

Licensed v/s Unlicensed deployments:

Many operators are now deploying WiFi in the unlicensed spectrum. This can help in the short term to alleviate the capacity problems but as more and more of this unlicensed spectrum nodes get deployed, they create interference between each other and make them unusable for anyone. An example was provided about Tokyo where in some areas, too many free WiFi hotspots means its unusable for anyone. One solution is to have one operator do all the logistics for the deployment and other operators can pay to use the service. Who (operator) would be the first one to go through the process of deploying everything first? Everyone would prefer wait and watch approach.

Providing free WiFi: 

The consensus was that the free WiFi provided by operators don't give any additional benefit to them and there isn't much of a business case. 

Consumer awareness for residential Femtocells:

Globally, not much effort is being done by the operator to make the end users aware of residential Femtocells and this is hampering the take-up  A point was made about when Vodafone launched their product, Vodafone Access Gateway (VAG), it was perceived as negative thing because the ads show that if the coverage was poor you can install this to improve coverage. From a users perspective, it showed that the network had poor coverage. Still consumer awareness is important, how to do it?

Placement of Small Cells:

Where should the public small cells (metrocells) be placed. The Biggest challenges are:

* Site Acquisition is the biggest problem. - This is a bigger problem if lap posts are sought to deploy on public locations

* Rent

* Planning

* Installation

* Power - Lamp posts are centrally switched off, so small cells on laamp posts may need alternative sources

* Power meter if used in a shared location

* Bullet proof (especially in the US)

* Backhaul - especially is non line of sight case.

* Health concerns (if visible)

* Visual appearance

* Opex

Backhaul:

Operators should be clearer in what they want. Right now the vendors are pushing the solutions that operators not necessarily need and not giving what the operators want. The Backhaul should be more flexible and future proof. It should be able to cater for upcoming technologies like Carrier Aggregation, CoMP, etc.

Shared v/s Dedicated carrier for 3G Small Cells:

Dedicated carrier is ideal but is not easily possible for most operators. When shared carrier is used it causes interference and handovers are not easy. 

Interoperability in the new hardware equipment for support of small cells:

Certain vendors are still not creating the the networks that can interwork with other vendors equipment. As we are moving towards LTE, this seems to be a much bigger problem. Sprint for example has 3 completely different networks in the US with no interoperability between them. Standards are not helping either as they do not dictate implementation. 

Some Interesting discussions on Case studies, Business Cases, etc.

Mosaic Telecom:
* Deployed residential Femtocells
* Deployed for coverage purpose
* Dont have handover capability yet
* Want to be able to deploy Microcells/Small Cells on Highways, around 1-2Km radius
* Their typical Microcells use 40W output power
* The cost of deployment if Macro using cabinet, antenna, etc is roughly 100K per site.

Telefonica, O2 trials in UK
* To get access to council lamp posts, it was required that the bidder offer free WiFi
* O2 set a high bar by paying lot of money to the councils in London, but this is not a sustainable model

A Business case for carrier neutral WiFi on light pole in Lima, Peru
* Each light pole can have 3 different locations
* The retail business case is to get the user to usse the offering and maybe offer the operator services, tempting to move to this operator from current one
* There can be a wholesale case of selling the WiFi capacity in bulk to companies, organisations

Some interesting statistics thrown up:

* WiFi cell radius is 30m in South America

* 83% of people in US think that operators should provide free WiFi because of lousy coverage of the mobile network.

* The first 4000 customers of a WiMax operator were using an average of 750 MB per day, 22.5GB per month.

* Some fixed Internet operators are now thinking of putting a cap on unlimited offering at 350GB per month.

There were no consensus and conclusions for many items so feel free to write your opinion in the comments.

Whats inside a Picocell?

Interesting pic from Public wireless:

• Intelligent Cell Control & Management Boards
  – Evolved OA&M for remote system management and monitoring
• Single/Multi Baseband Boards
• Digital Carrier Boards
• RF Chains / Power Amplifiers
• Various WAN Backhaul Modules
  – Wireline
    – Fiber, DOCSIS, Ethernet
  – Wireless
    – Satellite, NLOS, Microwave
• Power Supply + Battery Backup
• IP67 Outdoor thermal design

The presentation is available from Small Cell Forum website here.

Radio Challenges and Opportunities for Large Scale Small Cell Deployments

Here is another presentation by Keima at our Small Cells Event. Their last presentation on "Twitter et al. for Small Cell Planning" was a hit and has racked up over 9000 views on slideshare.

Radio Challenges and Opportunities for Large Scale Small Cell Deployments from 3G4G

Building the World’s Largest Residential Small-Cell network

Presentation by Nick Johnson, CTO of IP.Access in Cambridge Wireless Small Cells event.

Building the World’s Largest Residential Small-Cell network from Zahid Ghadialy

Small Cell Backhaul Solution Types

This is from a presentation by Julius Robson of CBNL, representing NGMN in the Cambridge Wireless Small Cells SIG event.

Interesting to see all possible options for Backhaul for small cells.

The presentation is available to view and download from here.

Related blog posts:

• Two interesting NGMN papers on Backhaul
• Couple of presentations on Backhaul

Small Cells as a Service - SCaaS

Last year I blogged about Femtocell as a Service (FaaS) but since we are talking in terms of Small Cell, we can use the term SCaaS that can form a superset to FaaS. This is from a presentation by Prof. Simon Saunders, in the Cambridge Wireless event.

Available to download from slideshare.