Signaling Crunch? Femtos to the rescue

The femtocell chipset vendor picoChip announced today that it has been able to provide an additional capability in its PC3x3 chipset series called smartSignaling. This includes the PC313 and PC323 chipsets which supports Rx Diversity. With this functionality picoChip claims to be able support 2x-3x more users at the same power level.

With smartSignaling enabled in their Rx Diversity chipsets, through a firmware upgrade they can support up to 400 ‘always on’ devices on a femtocell.These devices mainly include smart phones, which have their push email and other notification applications on constantly resulting in a signaling deluge. ABI Research’s latest smartphone estimates show that the 2009 saw a 25% growth in smartphone penetration compared to 2008 with penetration levels in 2010 expected to reach 18% by end 2010.

I queried them on the 400 user estimate which looks to be a statistical estimate and is not a hard and fast rule. It might be higher but could also be lower, but am not sure how low.

In an office environment while you could have upto 40-60 users actively making calls or data sessions on a femtocell, the rest of the idle users also would need to be accounted for especially when smart phones are involved. Typically if 15% of the office staff is using up active data capacity, the rest 85% need to be accounted for their idle mode signaling. Therefore doing the math, with 60 active user sessions you need around 340 idle mode sessions. This seems like a good benchmark to work with. picoChip says that this capability can be supported on closed, open or hybrid mode and doesn’t matter. However in closed mode they would need all the 400 users to be on the whitelist.

This level of signaling offload looks like a unique feature set to picoChip (at least for the moment) and strengthens the case for femtocells as not just a capacity offload solution but as a signaling offload solution as well. Compared to WiFi offload this gives femtocells an edge for sure, as WiFi is primarily meant to offload capacity and not signaling traffic. With collapsed RNCs femtos are able to take most of the signaling traffic off the operator core network. There seems to be a general revival in interest towards enterprise femtocells and the main reason is the data explosion from smartphones many of which are found in offices. Having spoken to many of the large operators, this seems to be a problem that needs urgent fixing, and WiFi doesn’t seem to be a long-term solution for them.

If femtocells can offload a significant amount of signaling traffic apart from data traffic for operators, it could become a much more cost effective solution than they had initially imagined, taking some strain off their core and RAN capex budgets, while bringing in additional enterprise user revenues.