Small Cells are a chameleon technology. 3G small cells will have stronger/earlier takeup than LTE. Carrier Wi-Fi is a stop gap solution for some. Data Offload isn't the right term to use. Prof Simon Saunders makes some provocative statements in this exclusive ThinkSmallCell interview which covers the hot topics in progress at the Small Cell Forum, of which he is Chairman.
Why do you think Small Cells seem to be much more widely accepted by the industry than residential femtocells alone?
I'd say it's because universality is the key point of small cells.
When we first embarked on the journey to develop femtocells, some looked for a single "killer product" specification that would be most attractive. But of course different mobile operators and different markets need different solutions – what might suit one may not be appropriate for another.
Small cells have now become a "chameleon" technology, which can be adapted to suit the different needs of each operator and market. Many had evaluated femtocell technology in its early stages and understood the technology, but it didn't match their needs.
Today, operators are buying into the whole ecosystem of small cells. There is greater acceptance of using multiple vendors in a radio network, and widespread understanding of how capacity can be multiplied through using more cells.
We now cover not just residential femtocells, but enterprise (large and small), metrocells and rural cells. This broad palette of small cell technology allows us to paint pictures appealing to all.
So while I can't say that every operator is deploying small cells today, pretty much everyone has a strategy which includes them in their network at some stage.
There's been a lot of focus on LTE recently. Do you have a view on how quickly 3G public access small cells will be deployed compared to LTE?
Actually there is some concern in the Forum that the focus on LTE small cells has taken away resources on 3G. The congestion we see today is on 3G networks using 3G devices and so the capacity relief really has to be 3G. We feel the same attention is not being given to 3G in the standard bodies as has been devoted to LTE. That's partly why we concentrated on 3G in our recent white paper on public access small cells.
For example, Telefónica O2 UK, speaking at the Small Cell World Summit last month was quite outspoken about how their spectrum capacity on their existing macrocell grid will run out by 2014 unless they use small cells. I'm not saying this applies to all operators by any means, but we've found that adopting a small cell strategy has not been a hard sell to most operators. The Forum now has to quietly focus on delivery to ensure the industry can meet its commitments.
We are in a similar position as regards planning rules to the early days of GSM mobile networks in the 1990's. Nobody really knows how many small cells will be needed, what type or where they will be located. There will be new rules of the game in every case. While the industry has a good starting point and is putting a lot of thought into it, the answers aren't definitively known.
Has there been Forum interest in multi-operator solutions, where small cells are shared between networks?
This topic is under discussion – everything from sharing space to sharing spectrum. Operators do want to have the capability for sharing functionality, but will ultimately make the choice of whether to deploy it in their own situation.
Another view is that we need to ensure we have some "joined up thinking". Practical considerations such as making best use of "street furniture" (i.e. avoiding a separate operator's small cell on alternate lampposts) and other physical or logistical constraints will be important.
Also, we can't afford to have too many different variations of products – the diversity could mean that the benefits of economies of scale would not be fully realized.
Carrier Wi-Fi has been a hot topic this year. How does this fit with cellular small cell takeup?
We have seen a lot of activity and interest recently. Operators seem keen to adopt and deploy HotSpot 2.0 which will provide a more seamless customer experience. But it will take a long time to deploy this technology fully.
I've heard some operators viewing Wi-Fi as a stop gap technology in preparation for a longer term widespread small cell deployment. Today's public Wi-Fi hotspots could be upgraded/replaced later with 3G and/or LTE systems, having captured/reserved the site locations for the future. Many future small cells will incorporate Wi-Fi that has a small incremental cost to the product.
One term I don't really like personally is "Data Offload". I'd rather hear the term "Intelligent Traffic Management", where a mix of 3G, LTE and Wi-Fi wireless technology can be used to deliver a customer experience. This would balance the economics, device capability and technology to use the most appropriate radio link for each customer. Hotspot 2.0 is a relevant factor in achieving this goal, but by no means the whole story.
The Small Cell Forum will continue to look at joining up these technology options to provide the best solution and have already made significant steps towards this goal. You'll see that this is a major theme for the Forum with some announcements during the autumn.
Moving on to LTE now, how important do you see the X.2 open interface for the small cell industry?
[Ed note: The X.2 interface allows small cells and macrocells to interwork closely in an LTE network, jointly determining which cells provide service to each customer. Some vendors want to provide both small cell and macrocell basestations with proprietary interworking, while independent small cell vendors want to use X.2 to provide their own small cell underlay that works efficiently with the existing installed LTE macrocells]
We were pleased the topic came up so prominently at the conference. [Ed Note: Alcatel Lucent announced their full support for it including interoperability testing]
The Forum has an activity running on the requirements for LTE small cells, and we are still at an early stage. We are at a similar stage as we were for 3G femtocells in 2007, and are working towards a consensus of operator requirements. You might think that surprising, since there are already several LTE small cell products on offer and some already deployed in use today.
This won't be an easy task for the Forum and I don't expect us to complete it any time soon – certainly not less than 12 months. We can't design an interface from scratch as we did for Iu-h because there is already one defined by 3GPP in place.
Although we've barely started, the need is great and we want to give visibility of our work in this area. As part of this activity, we are working out our first LTE small cell plugfest where vendors can experiment and test interworking.
Some people look at the Forum as a standards body. Could you clarify where the standards work of the Forum ends and that of 3GPP and others begins?
We don't intend to be a standards body and publish our own standards, but instead provide direction for standards activity and some relevant content. By gaining industry consensus at an early stage, we can help to simplify the standards process and reduce the time taken to produce and agree new specifications.
Our mode of operation is to first establish the market need. We then look at what existing standards are out there and identify gaps. We then press on to fill that gap, through voluntary consensus around the shape of the solution. Our members can then take this to the relevant standards organizations through the normal channels.
By discussing directly between a group of small cell experts, rather than standards generalists, our meetings can resolve issues and agree conclusions quite quickly. This approach worked for femtocells in Iu-h in close cooperation with 3GPP and Broadband Forum and it can work again for X2 interoperability.
In exceptional cases, we've published our own documents. For example, the LTE scheduler algorithm was included in our FAPI (Femtocell API) specification. The topic was irrelevant to 3GPP, so there's no conflict. Its success is demonstrated in that many contracts today require compliance with this specification. In general, we much prefer to work with existing standards bodies and have established formal partnership agreements with them.