This post is by Daniel Dribinski, Co-Founder and CTO, Cellwize
Visit Cellwize at LTE World Summit: #MR11.

Amsterdam, June 23, 2014

LTE growth continues apace. Currently, there are over 300 LTE networks with around 250m subscribers globally. And it keeps increasing. As part of their deployment strategy, many mobile operators have adopted an LTE overlay approach. This involves deploying LTE on top of existing 2G and 3G networks. Overlay is regarded as the one of the fastest and arguably, the most cost effective approach to roll out LTE. There is no need to decommission an old network and replace it with a new network, with an overlay there’s only one network to operate, manage and monitor.


To deliver voice and SMS on most LTE networks mobile operators use Circuit Switch FallBack (CSFB) technology. So, when a LTE device makes or receives a voice call or text message, it switches to 3G or 2G to complete the call or text. Subscribers therefore can switch back and forth between the LTE network and legacy technologies. This “fall back”, if not implemented effectively, could result in serious Quality of Experience (QoE) issues for subscribers. Some callers feel a noticeable lag in call establishing times from a couple of seconds to even longer.

Self-Organizing Networks (SON) can address this issue. However Distributed SON (D-SON) would not be able to manage this transition and the fall back will certainly not be seamless. Why? That’s because D-SON solutions are not able to handle multi technology and multi-vendor equipment. A Centralized SON (C-SON) on the other hand will be able to manage this transition seamlessly.

So, what are they key considerations when selecting a C-SON solution?

Firstly, not all C-SON solutions are the same. A number of SON solutions don’t cover all the network layers. While the hype around 4G tends to dominate media headlines, 2G is the humble workhorse for many mobile operators around the globe and a number of SON solutions don’t even cover 2G. When selecting a C-SON solution, ensure that it can organize all the different network layers (2G, 3G, LTE) and distribute the load.

Secondly, not all mobile networks are homogenous. To be cost effective, mobile network operators have purchased equipment from multiple vendors. Integrating them to a SON that is not vendor agnostic will be nightmare. For smooth interoperability, the C-SON solution needs to work across different vendors.

Mobile networks gather vast amounts of information. Data on poor user experience, say for example during fall back, should be analyzed. In fact, some C-SON solutions can intelligently analyze Big Data and use this insight to optimize the network for subscribers. Bear in mind that only a handful of SON solutions can analyze Big Data.

Finally, take into account the drive towards virtualizing network services. The C-SON solution therefore must be NFV ready. This would not only future proof the overlay network, but will also champion efficiency and reduce CAPEX as engineers can fully automate their network functions via the cloud.

One network to rule them all

LTE was meant to be the panacea to increase capacity and improve subscriber experience – while boosting revenues and minimizing churn. To roll LTE out as fast as possible, even some of the world’s top mobile operators used overlay as their preferred method of deployment. One network to run 2G, 3G and LTE. Yes, subscribers can enjoy faster browsing with LTE, but they will not want to put up with latency every time they receive or make a call. That’s why it is more important than ever for mobile operators to deploy a robust multi RAT C-SON solution. It needs to work seamlessly. All the buzz around LTE has raised customer expectations. Operators can ill afford to let their subscribers down.

If you would like to find out more, visit Cellwize at LTE World Summit: stand #MR11.

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