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The First Live 3G to 4G/LTE Handoff


The industry tends to couple the LTE radio (the E-UTRAN) and the Evolved Packet Core (EPC).  However, the EPC is being standardized as the core network for all access mechanisms, including: LTE, 2G, 3G, non-3GPP, and even wireline networks.  The “open” EPC allows the operator to realize a truly converged packet core supporting all access technologies.  The planning around the EPC must consider how all of these access networks enter the core, interwork with legacy systems, maintain seamless mobility, and provide consistent and optimized services.

Cisco’s mobile packet core solution is designed for the evolution from 3G to 4G.  The ASR 5000 is the benchmark for today’s and tomorrow’s multimedia enabled core network. The ASR 5000 utilizes a simple, flexible distributed architecture that allows operators to support multiple access technologies concurrently, e.g., 2G, 3G and 4G, subscriber mobility management, and call control capabilities, as well as integrated intelligent In-line Services with policy enforcement. With its leading edge throughput, signaling and capacity, the ASR 5000 is the only product available today to support 3G mobile networks, and through software upgrades, support 4G functionality without forklift upgrades.

One of the challenges with the evolution to 4G is the ability to provide seamless mobility from 3G networks to 4G networks on day 1.  As new applications emerge, the requirement for seamless service mobility for data becomes critical.  For example, services such as messaging, push-to-talk, video, gaming, and enterprise security applications such as Virtual Private Networks (VPNs) require seamless service mobility to be viable. In the not so distant future, mobile users will soon be able to take part in a video chat while downloading a movie and writing e-mails with a mobile device. Providing content such as movies and live gaming without seamless service mobility will severely impact the user experience. Finally, there is nothing worse than a location-based service that is disrupted due to a handover which either takes too long to complete or results in a change in IP address—you may miss that right turn.

Cisco demonstrated the first live 3G to 4G handover in the industry at Mobile World Congress. At CTIA 2010 in Las Vegas, Cisco will again be demonstrating a live handover from both 3G to 4G and 4G to 3G with seamless mobility for mobile video. The demonstration also shows the ASR 5000’s ability to support both 3G and 4G functions in a single node.

Jonathan Morgan is a member of the Service Provider Mobility marketing team working, writing, and thinking about Evolved Packet Core solutions.  You can read Jon's tweets at


Hi Jonathan,

I'm looking forward to seeing the Cisco 3G to 4G handover demo at CTIA.

Are you familiar with the demo of LTE to CDMA handover by LG at the CES in January?



Hi Mike,

Please stop by.  I'll be there all week discussing the solutions.

I am aware of the LG announcement.  Our demonstration focuses on the standard EPC network portion of the handoff on the core network side.



I will definitely stop by. I assumed that you would be emphasizing the EPC, and I am looking forward to learning more about that.




Hi Jon - not especially urgent, but if you have time: What are your thoughts on preserving / translating quality-of-service as a user moves from LTE/EPC to 3G?

If an application/session is allocated an EPS bearer with specific QCI, what happens when the user roams to 3G? Or vice versa, a user roaming in from 3G to EPS?

My EPC text book talks about this, but ends up saying, "we'll have to see how that works out"


Hi Gabriel,

The short answer (I'm traveling and will expand later) is that QoS will be preserved during the handover.  There is a mapping defined by 3GPP between the 9 QCI (LTE) classes and the 4 QoS classes (UMTS). One of the key goals is of LTE standardization was to ensure backward compatibility with UMTS QoS. Obviously, the 3G equipment has to support the QoS classes to start.




I just wanted to post a follow up now that CTIA has come and gone.  The demo went extremely well at CTIA. It's obvious that the migration to LTE/EPC is on the minds of many people.

One of the challenges of a video handover demo is that when it works, it just works.  The video stays running and you don't see any changes as you do the handover.  I'm amazed that some of the younger people with good eyes can tell the quality difference between 3G and 4G.

Besides the 3G/4G handoff, the other hot topic at the booth for mobililty was monetization.  We showed a demo on how operators can monetize their networks today.  I think this is an area we'll be talking about quite often in the next 3-18 months.

That's all for now.


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