Femtocells aren’t the only promise of a new system architecture to transform data handling for mobile networks. With the recent introduction of 4G/LTE, some vendors are proposing other radical changes to the flow of data through the network.
Mobile Data Offload Bypass
In particular, Stoke have been very actively marketing their product, positioning this as a mobile data offload solution. Since this is also a term often used to describe the positioning of femtocells, I thought I’d investigate further.
In simple terms, Stoke offer a high capacity IP router platform which can be configured through software to do a lot of the data gateway functions found in core of mobile data networks. Specifically, it can replace the functionality found in the GGSN (Gateway GPRS Serving Node) which interfaces to the internet and other external devices.
Perhaps a better term for this solution is mobile core network bypass, rather than offload. It’s positioned between the radio access network (RNC, Femto Gateway etc) and the data core network (SGSN/GGSN etc.), filtering out potentially huge volumes of data traffic that would normally be routed through this way. As I see it, Stoke are competing with core network vendors like Ericsson, NSN, Huawei and Alcatel-Lucent that would otherwise continue to sell significant amounts of kit that would expand in capacity to match the traffic demand.
In simple terms, if Stoke’s boxes are significantly cheaper than their GGSN then it makes commercial sense for an operator to consider using them instead.
A Change in Topology
One of my concerns with this approach is that network operators typically have only a few SGSN/GGSN nodes, say between 2 and 10 depending on their size. In geographically large territories, larger operators may have more so that they can offload traffic to the internet without piping it across the country.
The other issue is that operators have typically bolted on a number of external boxes in the data path which perform functions including traffic shaping, prepaid data control, video optimization, firewalling and failover routing. All of these functions may need to be replicated or duplicated for use with the data bypass solution, increasing the complexity and operational cost.
Successful in Japan
Stoke has been extremely successful in Japan, selling large amounts of the equipment to NTT DoCoMo, the largest network operator there. The equipment is mostly used for their new LTE network (they don’t yet call it 4G there – the term 3.9G is used instead). Nonetheless, it’s quite a coup for a startup company to win the approval of such a demanding customer.
Relevant to Femtocells
Given the concerns I have given above about increasing the complexity and duplicating functionality, the approach would seem to be independent of any femtocell development program. The offload solution bypasses the data core network while femtocells bypass the outdoor radio access network, meeting in the middle with the common Iu interface.
As data volumes grow – and they are predicted to grow by orders of magnitude in the next few years – more radical approaches will be taken to scrutinize cost and efficiency. One potential area is for new data tariffs to be developed which bypass some of the more expensive elements. These could be based on device type (mobile data bypass can filter out traffic for specific device types, such as the iPad) or mobility support (restricted to one or a set of femtocells only). If the network architecture develops to match these emerging tariff plans and traffic patterns, innovative new pricing and marketing offers may appear.
Summary
This mobile data offload architecture in my view should be called mobile data bypass.
It is complementary to femtocells in that it bypasses the mobile data core network, where femtocells bypass the radio access network.
The additional operational complexity of the solution and support of associated mobile data systems (traffic shaping, prepaid limiting etc.) means that most of these systems must be replicated for it to match the current functionality or specific/simpler traffic could be targeted for special treatment.
