LTE EPC Core… Decisions, Decisions, Decisions!

The LTE standard separates the EPC Core (brain) from the RAN (Radio Access Network).  This is very different from the PMP broadband technology you might have been using for years.  Now that the EPC Core has been separated from the RAN, many are asking: What implementation type should I choose? & Where should it/they be located?

The LTE standard introduces a lot of differences in the way private industrial, public safety, and military networks are now planned, architected, designed, built, and operated.

Some of the key LTE differences over classic Broadband PMP are:

1. Now it is a full mobility network
2. The core intelligence is no longer in each sector installed on a tower, nor in a cluster controller, rather it is completely separate from the RAN. In fact, the EPC Core is made of a number of components as illustrated above.
3. Yes, it is completely standards-based (interoperability) vs. proprietary.

Of course, there are plenty of other differences between LTE and the proprietary broadband wireless devices, and the deeper you dive into the understanding of the standard, the more differences are identified.

Full mobility and standards-based are a given with LTE; they are fundamentals to LTE.  Hence, it would not make much sense to have an LTE network that would not offer mobility and completely standard compliance, because that’s Mobility!

As to the EPC Core, although it is needed and very well defined in the standard, it can be implemented in many ways.   The EPC Core can be implemented in a number of ways;

• Centralized – This is usually how commercial carriers usually deploy.  All nodes “attach” to a common host. Carriers are not measured on reliability and are not focused on mission-critical networks.  This implementation can also be very attractive when one is building a private LTE network. In this implementation, redundancy is achieved with high availability infrastructure.
• Distributed – This is much more common in industrial networks.  In this implementation, the nodes are separated and duplicated. Take an offshore O&G or military network as an example. These networks cannot go down, people’s lives depend on it.  Implementing a distributed EPC Core reduces and can eliminate the risk involved in the eventuality where there is a backhaul failure between the eNB and EPC Core.   As an example, picture three O&G offshore platforms each with a RAN network, controlled by a remote centralized EPC Core.  If there were a loss of the backhaul link between the RAN/eNB and EPC Core, the entire network would go down.  Decentralizing the EPC Core to each platform provides independence and network survival even if each platform is completely isolated. Having the HSS as a synchronized node across the different locations allows for easy User Equipment management.

Now that you picked the core implementation best suited for you, next is where do you host the EPC Core(s).  The EPC Core(s) can be implemented in three main categories:

• Remotely – This is usually the case with Tier One Carriers as they are usually completely centralized
• On-premise – This is when the EPC Core is local to the RAN network. This is usually the case with Distributed Core.
• Cloud-based – This is very attractive for small private networks where the operator does not have to meet strict SLA’s, such as found with tier 3 commercial operators or WISPs that do not plan to offer B2B or SLA based services.  Although very attractive initially due to CAPEX savings, this is changing rapidly as the price of Centralized or Distributed EPC Core is dropping traumatically.

It should also be noted that the EPC Core comes in different sizes and shapes and the more scalable ones can reside on a single router blade and grow much bigger and take single or even multiple dedicated, or virtual, server(s).

So, in summary, when you are planning a private LTE network, you must carefully decide:

1. What implementation is best suited for today’s needs, and going forward? (Centralized/Decentralized).
2. The location where the EPC Core(s) is or are to be located? (Remotely/On-premise/Cloud). Remember that if the connection between the RAN and the EPC Core is lost, the RAN can no longer operate and maintain communications with the UE’s.
3. Architecture & Design Flexibility, it is important to note here that although on day one you may need a specific implementation type and location for your EPC Core(s), you may just have to alter this with time and changing requirements from your internal or external client. Thus, it is critical to choose the right manufacturer partner(s) that can accommodate all the variations mentioned above simply and gracefully.

Much more can be written on the important decisions regarding the EPC Core(s) topic… and I will on his blog.  In the meantime, if you have questions or comments please contact me.

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