It seems almost every year that the forecasts for widespread small cell take-up shift back another 12 months, although we shouldn't forget there are already over 10 million (mostly residential) small cells deployed to date.
We asked Todd Mersch, General Manager for Software and Solutions at Radisys, if he is particularly optimistic about LTE small cells and if he feels they will evolve alongside Carrier Wi-Fi, with SON playing an important part.
What timescales would you forecast and what signs should we look out for?
I believe we'll see three significant leaps, equally spread over the next 18 months.
- For the remainder of 2014, we should see significant market expansion. There are many trials ongoing, especially of LTE urban and multi-mode products, which will move into the commercial deployment phase.
- During first half of 2015, we'll see a couple of significant LTE Advanced features coming through – specifically Carrier Aggregation and eICIC.
- The second half of 2015 should see carriers leverage the small cell networks they will have begun to put in place, with more sophisticated LTE-A features such as multimedia broadcast. This extensive layer will provide the capacity to support the growing "Internet of Things" ecosystem.
What use cases will be most popular?
Operators evolve their small cell deployments through a series of stages.
- Coverage comes first, initially addressing the residential and SOHO locations with poor indoor service. This evolves to dealing properly with public access indoor venues.
- Capacity follows, targeting traffic hotspots and expanding throughput by offloading more heavily congested cells. We see this for public access both indoor and outdoors.
- Maturity comes later, adding applications and enhancements. These include zone based services, including presence and location as well as LTE-Advanced features which increase performance.
I think that once we have more or less ubiquitous coverage and capacity in place, then this will open up a huge latent demand. This provides an opportunity to take the system to the next level, turbo-charging the small cell industry.
Where does Wi-Fi fit in?
Many small cells now have dual-band Wi-Fi capability built in – this has become a default requirement for Enterprise and Urban markets. Carrier Wi-Fi is being deployed ahead of, and alongside, many small cell rollouts. All that traffic needs to be backhauled, groomed and managed into the core network.
We expect to see closer synergy when managing both Carrier Wi-Fi and small cell traffic, aggregating both through a shared/common edge gateway. What's more, we can add intelligence at this point to support those services and advanced applications for the maturity phase.
In the longer term, I could see the industry evolving to accept a NaaS (Network as a Service) business model using an Intelligent Edge Gateway.
You've recently announced a SON partnership with Airhop. Where does that fit?
SON (Self Organising Network) software consists of two main elements:
- the centralised software (C-SON) which orchestrates across a wide area, and
- the distributed element (D-SON) embedded in the small cells which reacts quickly to changes in the local environment.
There's also a hybrid model, where SON functionality can reside in a SON server within the RAN.
A common scenario is for each small cell vendor to provide their own D-SON while another 3rd party provides the C-SON. However, we find that operators want to select a single SON solution. AirHop's eSON uses a client-server architecture to provide both components, and can orchestrate both macrocell and small cell layers.
Our partnership with AirHop and Broadcom demonstrates the feasibility of this approach, tightly integrating the eSON functionality with the hardware capabilities built into the silicon. We're currently trialling the solution with selected customers. It reduces risk and accelerates the time to market by being pre-integrated and pre-verified.
To some people, SON is still seen as somewhat of a black art. I believe that as more work goes into interference mitigation in particular, we'll see this become a widely accepted method to increase capacity and quality.