Where sold only on the basis of improving indoor mobile phone reception, femtocells have to compete with several alternatives. Dual mode WiFi and Signal Boosters are two specific alternatives they must overcome.
The nationwide launch of Sprint’s Airave femtocell in August 2008 has heralded mostly positive reviews – excellent signal strength, great voice quality, easy installation. Their target market is customers with poor indoor coverage, rather than data or connected home use. Indeed, the product is very much a 2G system, not supporting high speed data, and the tariff plans give no discount for SMS or data use.
But it directly competes with solutions for poor coverage including active signal boosters and Dual-Mode WiFi/cellular phones. Which of these solutions are available, and what are the tradeoffs?
What causes poor cellphone coverage?
Poor coverage can be down to the specific phone model, as was initially reported with the 3G iPhone launched in August 2008 (and later addressed by a firmware update pushed automatically to all devices).
More commonly it's due to distance from the cell tower, geographic features (hills, mountains, buildings) in the way and/or being behind walls or basements which reduce signal levels.
Alternative solutions for poor cellphone coverage
Here are a variety of alternative means of receiving your mobile phone calls when at home in a poor coverage area:
|Use call forwarding to redirect calls to your landline phone||Straightforward to setup from your phone||Unless activated manually each time you return home, this could cause calls to be picked up by other members of the family or ring before diverting to voicemail. Unanswered calls may not divert to mobile voicemail.||Call charges may apply, or be included in bundled minutes.|
|Use a VoIP solution which directs calls to both fixed and mobile phone simultaneously||
You can then answer either one.
If travelling, you can use your VoIP service to receive calls avoiding roaming charges.
|More complex to setup, requires a new/different phone number, more potential for errors||VoIP subscription and call charges.|
|Use a wired indoor antenna. A docking station or wired connection is required to connect to the phone, which then amplifies the signal through an external antenna||Works with any phone, any operator.||Mobile phone cannot be used as cordless device, wandering about the house, but is very much tethered to a fixed location. Call handover when entering or leaving the building won’t work. Requires mains power||Cost between $40 and $100.|
|Use a wireless indoor signal booster. Installation of booster unit with cable to external roof antenna.||Works with any phone, any operator. (Boosters are frequency band specific, but dual-band formats are also available)||Requires installation and cabling, involving access to the roof and routing the cable inside the property. Requires mains power||Cost $300-400|
|Use a dual-mode WiFi/Cellular service such as HotSpot@Home from T-Mobile||Works with any WiFi including when travelling to hotels, public areas etc.||Requires specific WiFi/cellular phone, supporting mobile operator, broadband connection||Cost of WiFi/Cellphone (Free with some plans) + hotspot ($30). Plans including unlimited hotspot calls from $30/month.|
|Use a femtocell, when they become commercially available.||Self installing. Works with any standard 3G phone.||Requires a broadband connection||$99 + $4.99/month (Sprint, USA).|
Let’s explore wireless signal boosters further.
These are not legally permitted in many countries and are not cheap compared to femtocells today - $300 rather than $99 for Sprint’s Airave. Take the YX510 as an example (the reviews on Amazon are worth reading too).
For the customer, it has benefits including:
- no ongoing $4.99 monthly charge
- no broadband
- no operator lockin (you can use this on other mobile networks)
- no cost if others use it (it doesn’t affect your mobile broadband usage quota)
- longer mobile phone battery life (lower power transmission to reach only the signal booster)
- works with all phones
- you own it outright.
- High price ($300)
- Difficult to install (cabling, roof access etc.)
- Dependent on signal from nearest cell tower
Impact on the wide area network
The flipside is how it affects the mobile operator network and other users. Signal boosters operate by re-broadcasting the signal from your phone in the same way as a megaphone amplifies your voice. This can seriously impact the operators carefully tuned radio plan.
Now imagine if you are in a remote farmhouse miles from the nearest cellphone tower. Using a booster is like standing on top of the house shouting with a megaphone. These boosters work both ways (transmit and receive) so you should also be able to pickup weak signals and improve reception – those calling you will sound clearer.
From the mobile phone operator’s perspective, you now appear as a much stronger signal, but which can be controlled in the normal way. Signal transmit power levels can be remotely controlled by the nearby cellsite to the minimum level which reduces interference with other users. A few stray boosters used in this way probably don’t impact the overall radio performance in a sparsely populated area.
In more densely populated areas, the analogy of giving everyone a megaphone becomes more appropriate. Those using or requiring such signal boosters are probably located in obscure and difficult to reach coverage areas. By radically increasing their transmission power without considering the nearby radio environment, these can wreak havoc within the carefully planned radio transmission plan, significantly affecting the performance and user experience of all nearby mobile phones. Calls may be dropped; phones may need to transmit with higher signal power thus reducing overall cell capacity and range.
For these reasons, signal boosters are outlawed in many countries.
Where allowed, they do compete directly with the simple poor coverage business case. Femtocells will therefore have to sell at a lower price, be easier to install and entice customers with other benefits.