What comprises a Femtocell Gateway?
The Femtocell Gateway (FGW) is the aggregation point at the edge of the network for tens of thousands of femtocell access point (FAP) connections. A FGW - whether standalone or integrated with other gateway functionality - is required for all 3G UMTS femtocells. It provides the standardized interfaces to the femtocell (Iuh) and to the core network (Iucs and Iups).
FGW connectivity includes both large numbers of IPsec secure tunnels to the femtocells and ATM bearers into the circuit core. In some cases, circuit switched PDH interfaces are still needed where operators continue to use older MSC voice switches.
High availability is essential because the FGW supports hundreds of thousands of individual femtocells.
Administration and configuration functions for the TR.069 standard used to manage the femtocells can either be provided standalone or integrated into the gateway.
Scalability is also mandatory, with femto gateways needing to grow in size to support between 100,000 and 500,000 femtocells in a single gateway.
What does Continuous Computing provide as a Femtocell Gateway?
We have built a reference FGW platform which can be used by our customers, who are network equipment providers (NEPs), to develop and productise their own femtocell gateway quickly and cost-effectively.
Our FGW reference platform consists of Trillium Femtocell software running on industry standard, low cost bladed ATCA hardware. Called the FlexTCA platform, this is a pre-integrated, scalable ATCA system which takes up between 6U and 12U rack space. A single cabinet could have 3x 12U racks to provide high capacity.
Inside each FlexTCA FGW system, this provides:
- Load balancing
- Iu and Iuh signaling
- Bolt-on blocks for ATM connectivity
- A range of packet processing engines in blades
A key part of the FlexTCA FGW system is our flagship PP50 packet processing blade, which uses hardware accelerators to handle GTP tunnels, IPsec security encoding and RTP streams. There's no need for a separate IPsec gateway.
An add-on blade can do the ACS function for TR.069 management in the same chassis.
What capacity does this provide?
We can support 50,000 to 75,000 femtocell access points per 12U chassis. By fitting three 12U chassis into a single cabinet or rack, this handles some 225,000 femtocells.
Bear in mind that each can be handling up to 4 or 8 subscribers per femtocell, giving a total capacity of some 1 million simultaneous calls.
What other features are required?
We've built Deep Packet Inspection (DPI) into the FGW system, so that traffic prioritization rules such as enforcing QoS policies, rate limiting and voice prioritization can be implemented by the operator.
For example, with high data traffic levels, it makes sense to offload the data sessions to the internet directly from the gateway rather than take up core network resources. Intelligent traffic offload, using DPI rules based on policies, can offload at the gateway; we provide this capability.
Legal intercept is also possible on the Femtocell Gateway - for example, this would be needed where data offload is used. Again, DPI functionality is critical for this function.
Note too that all femtocell gateways need to be Highly Available (HA, also known as 99.999% availability, or "5 nines"), and our design provides this at the hardware, middleware, and Trillium software levels. This is a robust, carrier-class sytem; there is no disruption to traffic as a result of individual component failures.
When is this reference design available?
Our complete reference design on the FlexTCA platform is available today. This includes all ATCA hardware, HA middleware, Trillium protocol stacks and FGW reference applications.
We also have a fully compliant Trillium Iuh stack which has been shipped to multiple customers already.
Our current solution is based on an ACTA 10G platform, supporting 10Gbit/s throughput for each individual card. We're working on a 40G platform next which we'll bring to market next year, intending to increase the capacity by 4x in the same footprint.
Who makes femtocell gateways today and will this change?
Tier 1 and 2 equipment vendors dominate the femtocell gateway market today and I don't expect this to change much.
Femtocell access point providers include DSL broadband and Home Gateway vendors, who are quite a different set of customers.
Today's Femtocell Gateways are provided by mainstream RAN vendors such as
- Nokia Siemens Networks
- Alcatel Lucent
Some of the independent femtocell vendors also have their own
There are also a couple of independent femtocell gateway providers
- Kineto Wireless
Several major Tier-1 vendors are trying to build their own end-to-end solution on their own, sometimes using components from other smaller vendors.
Operators are still likely to rely on the Tier 1 players to deliver a complete solution. They demand openness of the interfaces to allow choice of femtocell access points, which will keep the market competitive and drive costs down.
What about interoperability between femtocells and gateways?
There has been a big push for IOT (Interoperability) testing in the Femto Forum. A "plugfest" where femtocell and gateway providers will demonstrate interoperability using the Iuh standard interface is scheduled for March 2010. There was disappointment that this couldn't have been held earlier amongst all the industry participants, but we are still very excited that this will happen. Some participants would not have been ready before the planned date, and it was seen to be essential to have a critical mass of providers and significant players at the event. We are ready to go today and we demonstrated Iuh IOT along with Starent and picoChip during the Femtocells World Summit in June.
One other thing to note: Now that operators are confident that the Iuh standard will be implemented and meet their needs, they can launch today using pre-Iuh proprietary designs which can be software upgraded in the field at a later date. For Trillium customers this is just a simple software upgrade; no hardware change is required.
Any issues regarding interoperability?
The Femtocell Gateway doesn't see the air interface (the radio communications between handset and femtocell), so there's no issue regarding handset compatibility. The main issue is the Iuh interoperability for different femtocells.
The Release 8 standard has a gap in the authentication procedure between femtocell and gateway (i.e authentication of the femtocell device, not the handsets or users which it supports). Release 9 due out later this year will finalise this and probably include a couple of alternative options.
Femtocells will negotiate with the gateway regarding which type of authentication to use, meaning that all femtocell gateways will have to support both types of authentication but individual femtocells can be developed with either one.
Any special features needed for Enterprise femtocell applications?
No, there are no inherently special features required for enterprise femtocell applications; the technology is the same as with residential femtocells. Note that regardless of enterprise or residential femtocell deployment, Continuous Computing only provides the base platform for our customers (i.e., Trillium Femtocell software and ATCA platform hardware). They then add their own value added applications to address specific markets, which allows them to differentiate - which is critical.
This would include features such as those targeted specifically for enterprise markets.