IT Business Edge
Femtocell Complexity Drives Networking Complexity

November 21, 2008

Carl Weinschenk speaks with Cathy Zatloukal, President and CEO, MobileAccess.

Weinschenk: Are enterprises showing interest in femtocells?

Zatloukal: We’re not seeing a lot of them in the enterprise space at this point in time. That has a lot to do with the fact that it is a technology that enterprises want to understand a lot more about. They just got through the learning curve with Wi-Fi. If you talk to a lot of enterprises today, they will say that even though Wi-Fi appeared to be cost-effective, most say that the cost of maintaining it is much more than they expected.

Weinschenk: Is the analogy between Wi-Fi and femtocell deployment conceptual — things are more expensive than they initially seem — or actual, in that a lot of technology can be repurposed?

Zatloukal: Both. If you think about wireless networks and think about all the different overhead elements, it breaks down to multiple base stations, handoffs, frequency reuse and all these aspects. Femtocells are going to go through the same thing. The standards are more robust than Wi-Fi but enterprises are going to go down that path of learning to use multiple femtocells to create connectivity. They are going to find some challenges that are similar to the ones that they had with Wi-Fi.

Weinschenk: Please give an example of how people deploying femtocells can learn from the Wi-Fi experience.

Zatloukal: If you take Cisco Radio Resource Management software, for example, it continued to get more and more complex as it moved from data handoff to VoIP. There were a lot of channel management issues as more and more devices came on the network.

Weinschenk: What frequency management complexities do femtocells present?

Zatloukal: The ability for a device, whether it is a data device or VoIP, to move between femtocell coverage areas involves a good deal of frequency management. A complication with femtocells that is unique is that the frequency management in the building has to be to some degree mapped to outside networks. You have to make sure the channels used in the building are not stepping on the outdoor network. Frequency management has to be dealt with when setting up the network. The handoff demands sufficient overhead in the network and the administrative tools need to make sure that the device makes a clear connection to the next femtocell."

Weinschenk: What do you recommend?

Zatloukal: Our recommendation is that enterprises use an architecture in which femtocells are pooled in the telecomm closet and IT use products like ours to create a blanket of connectivity that you can assign to different positions on the grid.

Weinschenk: So your approach is to have the antenna in one place, but lead the signals to another place where they are processed?

Zatloukal: Femtocells come in three basic building blocks: There is a digital piece, there’s an RF piece and an antenna. Our system, which is an intelligent distribution system, takes the signal from the antenna – what you see in the ceiling – and puts it in our network and distributes it. You can group them on our distribution system. It looks like a grid on a map. We propose taking the femtocells and grouping them in a telecom closet and taking the output and putting into an intelligent distribution network.

Weinschenk: Is your system unique, or is this how the industry is moving?

Zatloukal: There are some manufacturers that offer products in some areas of our product portfolio. We tend to be more from the cellular network side. We flipped our philosophy and asked: What does the CIO or IT pro really need? In that context, let’s say that part of your employee population embraced WiMax. They have it in their laptops. Part of the employee base uses a smartphone that is EVDO-based. You are handling CDMA/EVDO femtocell and WiMax femtocells. All that technology can be networked in the ceiling separately, or you can have an infrastructure solution that allows seamless coverage for all the constituent elements and is very scalable. In other words, either you use a series of parallel networks or a common converged infrastructure for distribution.

Weinschenk: Sounds like some of the in-building designs of years ago.

Zatloukal: There definitely are a lot of products out there to support multiple wireless operators in a single infrastructure. But it is more complex when you introduce femtocells. You really have to have intelligence in the distribution system to deal with the unique attributes of technologies. For instance, WiMax is a 4G broadband service that has a type of antenna – called MIMO – that can be condensed into a very simple idea. You are taking a single antenna system and putting two antennas in. There are two different signal streams, and you take the best of what you are hearing. But some of the older systems are not smart enough to deal with two streams of wireless signals and make sure that the femtocells understand what you are doing.

Weinschenk: So a new approach is necessary.

Zatloukal: Femtocells use very low-output power devices. Macro base stations have very high power. The older solutions put the signals on a piece of cable and have enough power that even if the signal degrades, there is enough to drive it the longer distance to and from the base station. It works. If you start to do that with femtocells, there is not enough power to go all the way through the system. Then you add MIMO and you need electronics at the end of the system to deal with that. 802.11n is the same concept.

Weinschenk: So things are not going to get simpler.

Zatloukal: It’s going to get more complex. If you look at the U.S., even after the 700 MHz auction, only 60 percent of the spectrum available for wireless technology will have been allocated. More spectrum will be allocated over time. The second thing is that you have a lot of new wireless services being launched in the public safety area. The enterprise and the building owner have a responsibility to ensure connectivity. From that perspective, you also have fire and police departments to worry about. You may have general complexity that is three- , four- or five-fold more complex than it is today.