Small Cells as a Service (SCaaS) using NFV

If you have not read my earlier post on SCaaS, then check this out. If you have no idea what Network Function Virtualization (NFV) is, check this out.

In a recent presentation in CW, Interdigital suggested that they are working on some ideas where they can virtualize the small cells network in such a way to have multi-tenancy (multiple operators sharing pool of small cells resources). Here is the complete presentation embedded. Let me know what you think.

Interdigital: Virtualization – You Know More Than You Realize! from Zahid Ghadialy

Open, Closed and Hybrid Access Small Cells

A question that often keeps cropping up regularly is regarding the open access and closed access small cells. Before we look at the explanation of these cells, lets see the different types of cells (from 3GPP TS 36.304) in brief:

Acceptable cell: An "acceptable cell" is a cell on which the UE may camp to obtain limited service (originate emergency calls and receive ETWS and CMAS notifications).

Suitable cell: A "suitable cell" is a cell on which the UE may camp on to obtain normal service. It is mandatory for the UE to have a USIM card belonging to the operator to which this cell belongs.

Barred cell: A cell is "barred" if it is so indicated in the system information. Its not available for use by anyone.

Reserved cell: A cell is reserved if it is so indicated in system information. It is reserved for operator use only.

Restricted Cell: A cell on which camping is allowed, but access attempts are disallowed for UEs whose access classes are indicated as barred.

Camping on the cell: With the cell selection, the UE searches for a suitable cell of the selected PLMN and chooses that cell to provide available services, further the UE shall tune to its control channel. This choosing is known as "camping on the cell".

To keep the discussion simple, I have ignored that some UE's may belong to MVNO and the PLMN Id of the operator would be stored as Equivalent PLMN Id.

Now lets look at a simple explanation of the different types of small cells.

Open Access: All (suitable) cells are open access by default. This means that they can be accessed by any device belonging to the operator whom the cell belongs to. Some people also refer to these cells as Open Subscriber Group (OSG) cells.

Closed Access: A (suitable) cell is closed when only certain devices can camp on them. These devices form a part of whitelist stored in a database to allow camping on the cell. Devices that are not part of the whitelist are not allowed to camp on this cell, even though they belong to the same operator and this cell is a suitable cell. The devices are said to belong to ‘Closed Subscriber Group’ (CSG). The cell is said to be a CSG cell as its transmitting CSG Indication set to 'true' and the CSG Identity.

Residential Femtocells are generally Closed Access but there are exceptions. Softbank, Japan for example gives open access Femtocells that can also provide coverage to users nearby. Another example is the operator Free in France that also offers similar open access Femtocells.

Hybrid Access: A (suitable) cell can also be hybrid access, thereby allowing all devices that either belong to a CSG or non-CSG to camp onto it. A hybrid cell may offer prioritised and/or additional services to the users that belongs to the CSG it is a part of.

I am not aware of any Hybrid Access Small Cells deployment to date. Please feel free to correct me.

Small Cells Research Bible

Here is a detailed research on Small Cells from Mehdi Bennis and Walid Saad presented in IEEE Dyspan 2014, this month. Feel free to add any comments for questions you may have.

Recent Advances in Wireless Small Cell Networks from Zahid Ghadialy

AT&T: Small Cells advertisement and Cell On Wheels (COW)

Interesting Small Cells advert from AT&T:

In the recent Boston marathon on the weekend, they also used their COW (Cell on Wheels) to boost the service. Here is a picture from their official tweet account. To know more, check their tweet out below.

Gearing up with a COW (Cell on Wheels) to boost service at the @BostonMarathon. #itsourboston http://t.co/FaiNQizpup pic.twitter.com/3bWHo5RChG
— AT&T (@ATT) April 19, 2014

You can also see whats inside the COWs in the video below:

Unlocking Small Cells for the Enterprise - EE

Another excellent presentation by the UK operator EE in our Cambridge Wireless SIG. There was a discussion about the different options during deployment, which options are more preferable than others, etc.

Another point worth mentioning is the potential of Small Cells in emergency and disaster situations. We have seen similar deployments happening in Japan during the tsunami that occurred a few years back. The complete presentations as follows:

EE: Unlocking small cells for the enterprise from Zahid Ghadialy

Related links:

• Summary of CW Small Cell SIG event 'Stretching the Limits' by ThinkSmallCell
• Operator plans for the ultra-dense network by Caroline Gabriel
• LTE Deployment Dilemma - Quiz

Operator plans for the ultra-dense network

The following is from Rethink Wireless article last month:

Large-scale deployments of public access small cells are still in their infancy, but there is already talk of 'hyper-dense' networks to cope with hotspots of intense data usage. Most of this remains just talk, but Qualcomm - on the rampage in metrocells after a hesitant start- is showing off how the approach might work in reality. 

The chip giant, never averse to a bold demonstration, is claiming the densest network ever constructed in a working environment, equating to 1,000 cells per square kilometer (a neat figure given that Qualcomm's ongoing marketing campaign revolves around the '1,000x Data Challenge', predicting an increase of that magnitude over the coming decade). 

It has put the trial together for Sprint's TDD technology, working with Airspan, the WiMAX specialist that has evolved into a small cell vendor with heavy emphasis on self-organization and integrated backhaul.

We recently heard from Caroline Gabriel in our Cambridge Wireless Small Cells SIG this (last) week. This very interesting presentation below is from that event. A very important slide is the tools that are available for achieving this ultra-dense networks. Anyway, presentation as follows:

Operator plans for the ultra-dense network from Zahid Ghadialy

Smart ANDSF by NSN

I have blogged about Access Network Discovery and Selection Function (ANDSF) in great detail on the 3G4G blog here. Earlier this week I was hearing from NSN about their Smart ANDSF solution which is the standard ANDSF with enhancements to handle unpredictable load conditions. Here is their presentation from the webinar.

NSN: Grow Capacity from Zahid Ghadialy

HetNet and LTE Trends and Challenges

Metrocells and C-RAN has been a frequent area of discussion on this blog. A good post about Metrocells is available here and about C-RAN is available here and here.

I found a small and useful presentation in my collection that highlights the trends, opportunities and challenges with the HetNets. The presentation is embedded below:

HetNet and LTE trends from 3G4G Blogs

3G / 4G Small Cells Mobility Scenarios - 3GPP Technical Report

3GPP has an excellent Technical Report (TR) 37.803 that covers different mobility scenarios and enhancements for 3G HNB and 4G HeNB. Its an interesting read if you are involved in this activity. Embedded below for reference.

Mobility enhancements for Home Node B (HNB) and Home enhanced Node B (HeNB) from Zahid Ghadialy

Urban Small Cells

During the recently concluded Mobile World Congress (MWC), Small Cell Forum launched their 'Release 3' on Urban Small Cells. The following is an extract from their press release:

Release Three: Urban Foundations has been developed to help operators with the rollout of small cells in the important public access arena. It builds on two earlier releases that focused on the established market for residential small cells (Release One) and the growing market for enterprise small cells (Release Two).

Release Three addresses a step change in market evolution: the commercial deployment of small cells in the urban environment. It establishes the business case and market drivers for urban small cells. It also identifies and starts to address many of the technical, economic and operational challenges to successful deployment and the opportunities this market could offer.

As part of its Release Three output, the Forum commissioned an independent operator survey from consulting firm Maravedis-Rethink. The survey found that capacity, value-added services and the opportunity to integrate Wi-Fi were among the most commonly cited market drivers for urban small cells. Backhaul, optimal site acquisition, monetization and network management were identified as the primary concerns. 

Release Three addresses these varied issues realistically and coherently. Alongside the authoritative body of Small Cell Forum work it can already draw on, this Release includes 18 new and updated documents aimed at identifying demand and supporting operators in the deployment of urban small cells. These range from economic and commercial issues such as market drivers, business case and service opportunities to technical areas such as self-organizing networks, backhaul, Wi-Fi integration and network architecture as well as regulatory challenges and deployment processes.

To a lot of extent, this blog has focussed on Urban small cells mainly. Often, the Urban Small Cells are referred to as Metrocells. The term Meadowcells is now being used to differentiate the rural small cells. Urban Small cells come with their own set of problems, hence the release includes quite a few documents to help the operators look into their deployment. A list of documents from the Scf.Io is as follows:

SCF103	Urban Small Cells: Release overview
SCF096	Deployment issues for urban small cells
SCF095	Backhaul for urban small cells: a topic brief
SCF091	Small cell application programmers’ guide
SCF090	Small cell services in the urban environment
SCF089	Next generation hotspot-based integrated small cell Wi-Fi
SCF088	Urban small cell network architectures
SCF087	Business case for urban small cells
SCF086	Market drivers for urban small cells
SCF082	LTE eNB L1 API definition
SCF077	Urban SON use cases
SCF076	Regulatory aspects of small cells
SCF075	Synchronisation for LTE small cells
SCF050	Market status statistics Q1 2014 - Mobile Experts

A presentation made by the Small Cell Forum chairman, Gordon Mansfield is embedded below:

ThinkSmallCell has written an excellent report on MWC that is available here. A quick extract from that summary on the Urban Small cells as follows:

Tuesday saw the Small Cell Forum issue Release 3: Urban Foundation which contained a surprising number of documents (19). Gordon Mansfield, Chairman of SCF, told me it exceeded his expectations, especially since it followed so closely after December's Enterprise release. The same release co-ordination team have presided over another mammoth edition. The complete Urban document set will be published in June, now renumbered Release 4, and the roadmap for updates and further releases will be finalised in April. The Forum also has a new CEO, Sue Monihan, who brings expertise from running the GSMA North America organisation and I'm sure will continue to expand the remit, membership and influence of the organisation. She will continue to work part time for both organisations concurrently.

Many (but not all) organisations now seem to be focussing on LTE+Wi-Fi rather than 3G/LTE/W-Fi multi-mode for urban capacity solutions - something that Vodafone specifically stated during the conference.

Mike Schabel, VP Small Cells at Alcatel-Lucent, pointed out the radical shift from voice to data is still fairly recent and has had huge impact for operators. Their commercial activity in Small Cell trials and business opportunities has never been busier. Speaking at the conference, he said "I can't keep up" with the number of RFPs today. They are working with 65 operators around the world (without double counting). This is happening in all regions - it's all over the world. While the technologies are the same across the small cell sector, what varies are the different business drivers found across their different customers.

Randy Cox, Head of Small Cells at NSN, showed me their latest LTE+Wi-Fi Urban Small Cell. This is quite a compact unit (about the size of a large dinner plate), capable of up to 400 concurrent sessions/calls. It's very much a downsized macrocell, reusing the same TI silicon chipset and optionally connected through a Flexi-Zone controller. They aren't planning a 3G/LTE multi-mode product at the moment, believing that LTE is the future. "We are in this for the long term" he told me. They continue to support their existing femtocell customers (using NSN's femtocell gateway and Cisco/Ubiquisys small cells), but it seemed to me that their Small Cell focus had shifted firmly to LTE.

NEC bring their own LTE expertise from Japan, with a range of in-house products complemented by partner solutions, both for Small Cells and wireless backhaul. They'veselected Radisys as their LTE Small Cell software supplier for their next in-house products. They position themselves as a one-stop shop for the new last mile, offering to handle everything from the initial planning through operational management of a portfolio of equipment. They told me that where macrocell deployments might have had four or five standard templates or scenarios, they've seen more like 400 to 500 different use cases. I do hope that's an exaggeration!

I saw several supporting technologies to de-risk HetNet deployments, ranging from smarter RF planning tools with more Small Cell features, SON vendors making further inroads, test validation and performance loading. There is a wider ecosystem here, finding newer and smarter ways to plan, manage and validate the network which wouldn't be cost effective at scale using traditional methods. Highlights included ERCOM's integration with Infovista/Mentum, allowing emulation of huge numbers of users in real-world scenarios, characterising the behaviour of small and macrocells that can be fed back into the planning tool. IXIA also have a comprehensive test and validation suite, de-risking the rollout of new features or vendor equipment by pushing the envelope and exploring the limits - not just conformance testing against standards. Sources of usage data now include directly from the handset, not just the network. OpenSignal published their "Global State of LTE Report" with actual performance results from 6 million users worldwide. Apparently Sweden has the fastest LTE in the world. The average speed worldwide is now just over 10Mbps. This whole area of back office planning and network management is evolving rapidly with many new technologies, tools and approaches coming on stream. Don't be distracted by the concepts of SDN and NFV - there are many more relevant and beneficial changes to how networks are managed coming along.