Forget moving around the room and waving your arms in the air to get a better mobile signal: so-called "femtocells" have emerged this year as the saving grace for overloaded mobile networks plagued with blackspots – allowing you to install a miniature base station that will bring more bars than ever to more parts of your home or office. But how well do they work?
This was the question on our lips as we unpacked a trial unit provided by Optus and put it to the test in a typical Melbourne suburban home that's normally beset by reception problems. Missed calls, dropouts and poor conversation quality were common features of reception that usually hovered around one bar on our iPhone 3GS.
Data reception over the 3G network was equally shocking: baseline testing in 10 locations around the property, using the widely used SpeedTest iOS application, found that speeds ranged from 0.03Mbps download/0.05 upload in the kitchen to 0.17Mbps/0.02Mbps in the rear family room, to a peak of 3.91Mbps/0.32Mbps in the front yard.
Optus' Home Zone, as it is called, is designed to fix this situation by providing a stronger signal than the normal network for mobiles to latch onto. The femtocell plugs into any existing router, then registers itself onto Optus' mobile network and routes calls to and from the mobile network using the home's existing internet connection.
The device and service cost AU$5 per month — a charge that has led many critics to slam Optus for charging customers to improve deficiencies in its network. That said, it's a nominal fee, and its impact is lessened somewhat by an Optus decision to include unlimited local and STD calls from the primary mobile registered with the femtocell. This is reminiscent of a similar geographically linked service pioneered a decade ago by Hutchison Telecoms subsidiary Orange (now part of Three, subsumed into the Vodafone joint venture VHA Australia).
The Home Zone femtocell is about the same size as an ADSL modem, with a shockingly bright light that could, in a pinch, be used as emergency lighting during power blackouts. If you're installing the unit somewhere that dark is sometimes desirable — for example, in a bedroom — you may want to cover it with duct tape or invest in a pair of sunglasses.
The unit itself is an Alcatel-Lucent Home Cell v2 , which claims a maximum 100 mW transmission power and less than 10W power consumption, and operates in the 1900MHz frequency band used by Optus' network.
Thanks to the unit's built-in self-configuration tools, the Home Zone was a breeze to set-up: plug it into the mains outlet, plug the included Ethernet cable into the unit and into a switch or router on your network and sign up through the Optus Home Zone page.
During sign-up, you can register up to 11 Optus mobile numbers that can be used with the device, and up to four devices at any given time. The access control list will be checked automatically every time someone tries to make a call, to make sure that neighbours and passers-by don't try to piggyback onto your service.
We entered the serial number from the femtocell unit, registered our two most often used mobile numbers, and waited for the service to go live. And waited.
It's not clear just how long it took for the service to go live, but it wasn't working immediately, or 20 minutes after plugging it in. But it was working about two hours later, which we knew because we were getting four bars of reception — and making a mobile call invoked a quick three-note tone designed to indicate that the femtocell was indeed handling calls.
The most obvious application for femtocells is improving the strength of the mobile signal — and, in the process, the quality of voice conversations. In this, the femtocell didn't disappoint: reception went from one bar to four bars in the front room, and everywhere else on the property.
In general, this translated into better call quality: calls were clearer, with a more consistent volume and better voices. We also noticed that there were fewer people indicating they were having trouble hearing us, which had been a common complaint in the past.
That said, call quality was not perfect: on many occasions, we noticed a lag between when we would say something and when the respondent would recognise that we had talked. This is the kind of delay often seen on international calls, and may be reflective of the underlying voice over IP (VoIP) technology used by the femtocell.
It's also worth considering the implications; because the service depends on your broadband connection, you need to have a decent internet service that will support your calls, as well as your normal data usage. Optus says that the service requires a minimum 128Kbps download speed, but recommends at least 1Mbps/512Kbps to ensure that there's enough headroom for the unit's VoIP-encoded conversations.
In theory, at least, this means that it should be possible to block the femtocell's mobile calls by flooding the home internet connection. To test this, we downloaded a large file through BitTorrent. At lower speeds, call quality was maintained; however, at speeds of up to 1MB/sec, we were variously able and unable to initiate a mobile call through the femtocell. On the whole, however, conflicting data demands were generally not a problem, and voice call quality remained the same even under heavy downloading loads.
One persistent problem arose when we returned home after being out, at which time the mobile was still expecting to connect to a different cell. In this case, initiating a call through the Home Zone would produce a "Call Failed" message on the first attempt; when this happened, however, it was easily remedied by tapping a button to retry the call.
Although it's not widely advertised, another nice aspect of the femtocell is its ability to boost 3G data speeds in poor coverage areas. Many homes would use Wi-Fi for this, but Wi-Fi isn't perfect; in our test home, there are many areas where Wi-Fi signals are far less than optimal due to the presence of brick walls and other obstacles.
With the femtocell installed, we were able to register a significant improvement in download speeds at nearly every location around the house (see table). In the front room, for example, pre-femtocell 3G speeds of just 0.16Mbps/0.09Mbps jumped to 3.89Mbps/0.11Mbps, and latency was halved — from 299ms to 140ms. Speeds on the kerb in front of the house jumped from 0.49Mbps/0.30Mbps before the femtocell, to 2.29Mbps/0.12Mbps afterwards. Furthermore, we were able to maintain a data connection — albeit a very slow one — two houses away.
Indeed, when connecting to the femtocell, we were able to get mobile broadband speeds that were far higher than we normally achieve while out in the field. Speeds peaked at around 3.5Mbps download and never passed 0.12Mbps upload; as this was both well below the cable internet connection's speed, and was relatively consistent at different locations across the house, this likely reflects the peak performance available through Optus' service.
That said, speeds even through the femtocell-boosted 3G were still slower than those over Wi-Fi; you'd probably only want to be relying on 3G wireless in-home if you had already exceeded your monthly broadband quota, or if a guest wanted to get online via 3G and you wanted to force them to use their own wireless broadband quota rather than chewing through yours.
|Location||3G without femtocell |
DL/UL Mbps (latency)
|3G with femtocell |
DL/UL Mbps (latency)
DL/UL Mbps (latency)
|Kerb in front of house||0.49/0.30 (130ms)||2.29/0.12 (158ms)||3.16/0.46 (29ms)|
|In front of neighbour's house||0.49/0.29 (269ms)||1.40/0.11 (140ms)||0.40/0.02 (47ms)|
|In front yard||3.91/0.32 (19ms)||2.88/0.12 (137ms)||6.01/0.46 (39ms)|
|At front door||1.40/0.11 (140ms)||3.89/0.11 (128ms)||5.1/0.46 (27ms)|
|In front bedroom||0.16/0.09 (299ms)||3.89/0.11 (140ms)||11.71/0.46 (30ms)|
|In kitchen (near femtocell)||0.03/0.05 (305ms)||3.6/0.11 (170ms)||10.24/0.46 (22ms)|
|Lounge room (rear of house)||0.17/0.02 (246ms)||3.38/0.11 (171ms)||11.87/0.46 (22ms)|
|In backyard||1.85/0.12 (133ms)||3.23/0.11 (175ms)||6.87/0.46 (29ms)|
|In rear corner of lot||0.21/0.13 (297ms)||1.27/0.10 (178ms)||0.78/0.23 (31ms)|
|In brick backyard garage||0.08/0.33 (126ms)||0.58/0.11 (283ms)||No signal|
Whatever your philosophical leanings about paying to fill in Optus' network blackspots, there is a lot to like about the Home Zone service. True to its promise, we noticed improved voice call quality overall, although lag was occasionally noticeable. We also saw a boost to data performance, with femtocell-powered SpeedTest results surpassing 3Mbps indoors. These results confirmed that the Optus femtocell is not only able to fill in mobile blackspots, but can provide decent 3G broadband speeds — although Wi-Fi will still generally provides a faster and more readily usable option if you have it. Get this mainly if you make lots of calls from your mobile at home, and find poor reception to be a bane.