Most wireless infrastructure planners are now familiar with the Evolved Packet Core (EPC) for 4G Long Term Evolution (LTE) networks and how EPC elements perform in LTE deployments. 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?
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 increase 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.