Every day in large and small offices across America, business workers ignore the PC or desk phone and grab their smartphones for convenient voice, email and Internet access. But delivering high quality cellular service inside office buildings is a challenge for wireless carriers, especially for high-speed data which requires a particularly strong signal.
Traditional in-building solutions are expensive and take a long time to implement, but a new generation of "enterprise femtocells" (or picocells) offer a quicker and cheaper answer.
ANALYSIS: Femtocells, Wi-Fi to play growing role in mobile networks
Mobile operators are planning for better in-building coverage in future networks. Next generation heterogeneous network architectures will involve overlapping plots of indoor and outdoor coverage using a variety of macro cells, metro zones, picocells and femtocells.
But the technology to do this today with 3G networks already exists. Indeed, for consumers, AT&T, Sprint and Verizon all offer femtocells for customers who want to improve cellphone service at home. These devices simply plug into an existing fixed broadband Internet connection to connect back to the wireless carrier's core network, thereby generating a personal cellphone signal inside the subscriber's home.
The femtocell concept can quickly and easily be applied to small offices, and with some adaptations, can be scaled up to bigger buildings. These "enterprise femtocells," or picocells, represent a clear choice for larger business premises.
Compared to their residential counterparts, enterprise pico and femto cells offer higher power and greater capacity to cover more cellphone users in large and complex enterprise locations, ranging from office suites to multiple floors in large buildings, retail locations, car parks and many types of public spaces.
Other important differences between these devices and consumer femtocells include open access for all network users, two-way handover with the macro network, and active management by the wireless carrier.
Open access
Home femtocells usually operate in closed access mode, where the end customer authorizes which phones are allowed to make calls. In an enterprise, however, having to register each handset (including visitors) for each in-building cell is an unwanted burden, especially in an office using multiple cells. Therefore, enterprise class femtocells need to be configured for open access, so that service is improved for all network users.
This is especially important in environments where members of the public will come into range of the femtocell (which is much more likely for enterprise class devices than home femtocells, given their increased power and more public locations). Without open access, unauthorized handsets will suffer interference from the femtocell, which may degrade or even block service from the macro network.
Open access dramatically changes the amount of traffic carried on the femtocell -- not just voice and data calls, but also signaling traffic as phones come in and out of range of the femtocell in idle mode, generating location updates in the core network. This means that the core network infrastructure required to support enterprise femtocells must be dimensioned very differently from a residential deployment -- a Femto Gateway that can handle 20,000 residential femtocells may only be able to support 2,000 enterprise devices, for example.
Two-way handover
One significant limitation of the home femtocell is that a call that begins on the macro network cannot be handed over to the home femtocell when you get within range. This is not usually a problem for home users, but some carriers have admitted that a lack of hand-in capability has caused disappointment among business customers to whom they have offered a "souped-up" residential femtocell.
The need for two-way handover, combined with open access, requires a certain amount of cell planning when deploying enterprise femtocells. This means that the provisioning process is different from a typical plug'n'play residential femtocell. The process can still be automated, but the business logic is very different; so a provisioning system designed for mass-market femtocells is not well suited to enterprise deployments.
Active management
Home femtocells are passively managed. If a device goes off-air, it's likely that the end user has simply unplugged it -- perhaps they needed the electrical socket to do the vacuuming, for example. So carriers typically prefer to wait for the customer to report a fault. They certainly don't want alarms raised in the Network Operations Center for every potential issue -- most will be false alarms.
By contrast, the carrier will normally want an immediate alarm in the Network Operations Center if there is a potential problem with an enterprise femtocell which has been installed to provide cellphone coverage for an important business customer. For picocells -- often used by operators to increase capacity in locations such as train stations and sports stadiums -- this management function has always existed.
Today's picocells and enterprise femtocells solve all these issues, making it possible for operators and business users to dramatically improve in-building cellphone service. These devices offer the power and capacity to cover both the building and all the users, either singly or in combination with multiple picocells or enterprise femtocells. The operator management functions included as standard in these units make it possible to hand over calls within an office, between different floors or across a campus location.
The smartphone is now integral to business life. Knowledge workers are familiar with using enterprise applications and accessing email and the Internet from their smartphones when on the move, and they expect the same or better performance inside their offices. Using today's picocells and enterprise femtocells, carriers can ensure that their business customers achieve that goal.
About ip.access: Based in Cambridge, U.K., ip.access ltd is a leading manufacturer of cost-effective picocell and femtocell infrastructure solutions for GSM, GPRS, EDGE and 3G. These solutions bring IP and cellular technologies together to drive down costs and increase coverage and capacity of mobile networks.
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