- Published on Tuesday, 06 November 2012 19:28
- Written by David Chambers
Perhaps the industry has over-cooked the marketing hype, but we’ve seen growing interest on the internet from end-users wanting to buy their own residential small cell (previously named a femtocell). Here are some quick answers to common questions.
As we’ve said several times, the business case is particularly strong in North America, where the combination of poor mobile phone coverage and widely available domestic broadband service (plus the disposable income to pay) provide early market demand. We’d also expect strong early takeup in Japan which quickly adopts new technologies.
Where can I buy a residential small cell/femtocell?
Residential small cells (Femtocells) are today commercially available in many countries, across USA, Europe and Asia. It is expected that a few more may introduce the system in due course.
Each operator tends to market the product with their own distinctive brand name, and doesn't use the term femtocell or small cell in their marketing literature. Examples include Vodafone Sure Signal, Sprint Airave and AT&T 3G Microcell.
Who can I buy a residential small cell/femtocell from?
The femtocell equipment has to be managed by a licenced mobile phone operator, using the frequency spectrum that it paid (usually huge sums to) its government for. This differs radically from WiFi access points, which use unlicenced spectrum and can be setup pretty much anywhere.
Therefore, in order to work with your mobile phone, you will have to buy the femtocell from your mobile operator or a reseller.
Where can I use my residential small cell/femtocell – can I take it to my country/holiday home at weekends?
In the US, all small cells are required to include a GPS receiver. This serves three purposes:
Provide an accurate clock timing frequency reference (GPS is calibrated from Caesium atomic clocks), thus ensuring calls handover to/from the external cellphone network easily and don’t disrupt users nearby.
Determine which frequencies are licenced for use in the area, and use the correct ones.
Block usage outside licenced operating areas.
Additionally, small cells often have a 2G and 3G receiver which can scan for signals from external cellsites and determine the country and available networks. It can use this to identify if it has been moved since last used, because the local cellsite identities would have changed.
Therefore, taking the equipment to a different location in the same country could work, but would be known to the network operator. Some operators have considered charging for this “service”, although they don’t actually have to do anything other than bill for the privilege. Alternatively it could just be allowed.
However, taking the device with you on your travels abroad is much less likely to be successful. If you were in such a remote location that there was no outside mobile service but broadband was, then this would be possible. If its just a business trip to a mainstream hotel, then you would much less likely find this to be the case.
Can I have more than one residential small cell/femtocell at home?
Why not! (but not usually from the same mobile operator) Just as we see multiple cell towers from different operators in close proximity (there are three in the corners of my local football ground), it should be possible to do this in domestic premises. Small cells provided by different mobile phone operators will transmit at different frequencies, so providing there is some spatial separation (ie the units are not stacked directly on top of each other), then this should be feasible.
A limit of 4 or 8 simultaneous calls applies to each residential small cell. Additionally, the limited capacity of the broadband internet connection would be applied across all small cells sharing it.
Obviously, the phone companies will want (expect) end users to consolidate on a single mobile phone supplier for all family members in a home, sharing the same small cell. They may also be able to provide the broadband service as part of the package (we have seen “free broadband” offers from mobile operators in the UK for higher spending postpaid subscribers already). But there may be cases where users have different phone operators (eg a work phone), and might install a separate small cell in their study area for that purpose.
Small cell vendors also talk about using them in high traffic density office environments, effectively providing many independent cells each capable of handling 4 simultaneous calls. This competes with several other techniques widely deployed today, such as Distributed Antenna Systems (DAS), Remote Radio Heads and picocells. The business case to do this will be based around lower deployment costs, because the femtocells would be pretty much self-installing and self radio optimising.
I’d not expect domestic users to have more than one residential small cell from the same mobile phone network, but I have heard of cases where two have been installed to cover an exceptionally large/spread out residence. This required two independent DSL broadband lines to support them. In some exceptional cases, multiple femtocells may be installed from different operators.
Can I sell my residential small cell/femtocell on eBay when I’m done with it?
Probably. In the UK, Vodafone allow customers to resell their small cells and will reconnect them if sold on. Operators are likely to be quite wary of connecting equipment that they don’t know about into their systems, but where it is a traceable unit with known serial number, then this will be technically possible.
My suspicion is that the cost of small cells in the future will drop to a level where it’s not worthwhile. Subsidised small cells make it more likely that customers will buy the latest, new version.
Where permitted, it’s almost certain to be allowed only between users of the same mobile phone networks. The buyer will need to have checked they can register the residential small cell on their own account before purchasing it.
Can I reuse or transfer my residential small cell/femtocell to another mobile operator?
Standards, standards, standards. One of the great things about mobile phone systems (and particularly the GSM family) is that all equipment must comply with previous agreed specifications. Pretty much any phone sold anywhere in the world can work on any other mobile phone network of the same type – either through roaming or by swapping out the SIM card. Yes, there are a few places where these standards vary (frequencies used in the US differ, Japan didn’t deploy GSM), but this approach has been incredibly successful (87% of the worlds phones are GSM based).
Residential small cells also comply with these standards and so will work with pretty much any mobile phone using the same system. However, there are many different system architectures used to connect them back into the mobile phone operator’s systems. Specifically, the way in which the data connection is used over the broadband internet link varies widely and is often incompatible between different vendors.
Operators would much prefer if residential small cells/femtocells were completely transferable, because it allows them to trade-off purchase decisions between different suppliers and get the best deal. This was tried (and failed) for the GSM system, tried again (and failed) for the 3G UMTS system and is being tried again for LTE. Vendors supply both the small cell and the small cell gateway at the operator’s central site, and this is likely to be the case in the medium term.
Lastly, it may be obvious to the reader, but small cells are not designed and manufactured to work with different 3G radio technologies such as CDMA or UMTS in the same unit. Customers of Sprint or Verizon (which use CDMA) will not be able to use their femtocells on T-Mobile or AT&T Wireless (which use 3G UMTS/HSPA technology). Different hardware parts are required on the RF side, so its unlikely we'll see a dual-mode CDMA/UMTS residential small cell/femtocell in the future.
Want to buy a residential small cell for home or small office use? Read our list of network operators with commercial residential small cell services
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