EPC diagrams are available from vendors and standards groups, along with a few tutorials on planning an EPC deployment.
That's all very helpful, but mobile networks are already complex, largely because the problems they address are complex. LTE has added new issues to the previous challenges of 3G wireless networks. Combine those with 4G LTE network infrastructure and service evolution questions, and the result is that Evolved Packet Core planners face large and unique problems.
Luckily, operators that have either deployed or planned EPC infrastructure cite five key issues that need to be managed, and they provide recommendations on how to do so.
Evolved Packet Core Issue #1: LTE data services
In mature mobile markets, there has been a 4G technology divide, with WiMAX services aimed predominantly at data service models, and LTE evolving out of current 3G mobile services, whose initial mission was voice. That said, given how strong a technology LTE is for delivering data services, shouldn't it also be focused on data opportunities?
Tom Nolle President, CIMI Corp.
Most operators believe it should be. LTE planners say that it is critical to plan 4G LTE network deployment in terms of data services, which is why EPC planning is so important. If EPC principles are followed, then mobility management and registration are easily linked to IP Multimedia Subsystem (IMS) service control, and LTE voice services can be added as a control layer. The impact of voice traffic on the data plane would then be minimal.
Evolved Packet Core Issue #2: Networking the towers
Since 4G LTE network capacity per cell is 10 times or more the capacity of 3G technology, fully exploiting its benefits probably requires fiber-to-the-tower technology. The question is then about where the fiber should connect. The traditional method is to backhaul fiber to the local central office (CO).
But in EPC deployments, that would create an aggregation issue in central offices, which would only increases the CO requirement for fiber capacity outward to service points. So is the traditional approach the right one?
Operators have a growing conviction that the metro topology of EPC should create a series of wireless aggregation points to which fiber from the towers is homed. This is most practical in dense metro areas, of course, but as long as utility fiber or right-of-way is available, creating fiber paths from the tower to a node close to the service points for voice and data improves performance and Quality of Service (QoS) control.
Evolved Packet Core Issue #3: Mobile security
The advent of smart mobile devices generates a risk that mobile appliances could be used to attack one another, elements of the infrastructure, or even wireline sites, given higher mobile bandwidth. Mobile services also expose operators to the risk that customer information and location might be revealed and used in illegal activity. The question is whether to push mobile security as an appliance or a network issue.
Operators seem to agree that mobile security is a network issue, but they also recognize that many mobile applications (phone-as-credit-card, for example) demand a high level of handset/appliance security. Operators are looking for a service-based security system for mobile that lives in the network and can be extended via hotspots, femtocells and home services into the wireline space. Virtually all operators see this as a layer beyond EPC and IMS because it is most significant for Internet-based services.
Evolved Packet Core Issue #4: QoS and traffic management
While there is long-standing operator conviction that QoS is a major service differentiator, two emerging trends seem to counter that notion. First, the Internet has conditioned users to best-effort services, reducing the premium they'll pay for QoS. Second, regulators are wrestling with questions of net neutrality that may influence whether operators could charge for premium handling.
Most operators believe that traffic management for mobile networks will be an essential part of providing reasonable service quality to all, but they are concerned whether traffic management applications to provide premium handling will be profitable and acceptable. They are most likely to invest in approaches that are cost-effective in managing traffic at the level needed to assure network stability but are also expanded in scope to supply premium handling where it is legal and profitable. Most believe that EPC tunnel management provides the needed transport facilities but that registration and application security will be needed to link traffic flows with service policies.
Evolved Packet Core Issue #5: App developer programs
The last issue focuses on developer programs and mobile services. Operators have been impressed (and sometimes annoyed) at the success of application stores like the one Apple launched with its iPhone. They are also worried that a highly competitive smartphone and data appliance market may sap their own opportunities to provide premium mobile services. To offer application stores without differentiated applications to sell seems like a waste of an opportunity. But where can differentiation be created?
Most operators believe that exposing some service assets through developer programs and software tool kits is essential, but they are very concerned that exposure could threaten network stability. Operators consider some mechanism to isolate basic EPC processes from developers through a gateway to be essential in protecting service experiences to the user. Operators are working with equipment vendors to create the right model.
Using operator views as a guide
4G LTE network infrastructure planners should use operator consensus as a guideline in their own planning, recognizing that every mobile operator has a unique market and business model, unique regulatory oversight and unique current network infrastructure commitments. The best answers from the industry are only policy guidelines to be used in creating the best answer for your own company.
About the author: Tom Nolle is president of CIMI Corporation, a strategic consulting firm specializing in telecommunications and data communications since 1982. He is the publisher of Netwatcher, a journal addressing advanced telecommunications strategy issues. Check out his SearchTelecom.com networking blog Uncommon Wisdom.