Picocells in Action

Pico- and Femtocells have been a hotly debated topic at the Mobile World Congress this year and to my great pleasure I've been offered the opportunity to have a look at a real Picocell installation in a live network after returning home.

So one day, I was invited to visit an installation at a shopping mall, where a number of GSM picocells from IP.Access were deployed, as the surrounding macro network did not cover the interior of the mall very well. In essence, this means that the picocell was deployed as a coverage filler rather than to add capacity to the macro network.

It looks like the network operator using the picocells was not the only one having coverage problems, as I saw a number of repeater antennas throughout the building from other operators. Repeaters are another solution to get in-house coverage but I was told that while it sounds easy enough, they are rather tricky to deploy as permission is needed for the external antenna on the roof. Also, the coax cables running through the shopping center to the antennas inside are quite expensive and again a permission is required to lay the cables and install the antennas in the hallways.

Picocells on the other hand require no permission whatsoever and the installation is rather trivial: A phone line for DSL that serves as a backhaul link, a DSL modem and the picocell itself, that's all it takes. In the specific installation I was shown, an Ethernet switch was connected in addition as the DSL link was also used to connect the computers of the shop back to the mother ship. Quite a nice setup as the backhaul cost for the picocell is effectively zero that way.

I ran a couple of calls over the picocell and couldn't tell the difference in voice quality in the picocell compared from that in the macro network. Moving from the picocell to the macro network worked quite well as soon as I left the coverage area which was around 20 meters. I'd say there were only using a very low power output. In the opposite direction, however, the mobile lost coverage and had to perform a network search before the picocell was found. My test mobile revealed that the macro cell did not broadcast the parameters for reselecting into the picocell. Looks like it hasn't been configured correctly at the time I tried.

All in all, I was very impressed with the simplicity of the setup and not only the customers coming to the mall but also those that work there are probably quite happy to have the network there and are probably even unaware that their call is not handled by the macro network but is actually backhauled via a DSL IP connection.

Thanks for the visit, it was very insightful!