Mobile World Congress is upon us once again. Kicking off on Monday in Barcelona, this year's event will bring the heavyweights of the telecom world together at a time of rapid change for the industry.

SDxCentral will have full coverage of MWC from the ground in Barcelona. Here are a few of the key themes we'll be tracking.

Though production networks aren't expected until 2020, the roadmap is already being laid for ultra-fast 5G mobile networks. Europe and Asia have taken the lead in early R&D investments, with South Korea and the EU backing research labs and China's Huawei budgeting $600 million for 5G development through 2018.

But how will 5G work, and what role will emerging software-based network technology play? Those questions are still up in the air and are sure to be one of the hottest topics at MWC.

Carriers have been talking for a while about applying cloud principles to the radio access network (RAN). This could have implications for the software-defined world. Market Research Reports claims the cloud RAN will create a $5 billion market for SDN and NFV in 2020, and SK Telecom told Light Reading that the cloud RAN is one reason why it invested in the ONOS project.

Just over a year ago, reports based on documents leaked by Edward Snowden first emerged, detailing the NSA's electronic surveillance practices. The fallout of those revelations for U.S. telecom vendors is still unclear. Will international service providers turn away from U.S. vendors in fear of unwittingly granting state access to their networks?

The coming explosion of connected sensors, devices, and wearables looms just as network operators face security challenges of a scale and complexity never seen before. How will service providers and enterprises balance these demands, and what solutions are they looking for to secure the Internet of Things?

Carriers are fairly well sold on the concept of network functions virtualization (NFV) at this point. Implementation will require pinning down an approach to orchestration, the systems used for deploying and managing virtual network functions. Will open source platforms lead the way? Expect some major announcements. (For more info, check out Roy Chua's 2015 NFV predictions.)

He might not strike you as "software-defined," but we're intrigued that the hip-hop star and founding member of The Black Eyed Peas is slated to join Vodafone Europe CEO David Hose and others on a panel discussion about mobile and music.

Stay tuned for full coverage from Barcelona!