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Meeting the Challenges of the New Mobile Network: The Evolved Packet Core

We all know the story: over 5 billion mobile subscribers worldwide, new powerful mobile devices like tablets and smartphones, a shift from voice to multi-media rich applications like video.

Suffice to say that the existing legacy networks won’t cut it. Equipment vendors and service providers are responding with the complex task of adding enhancements while maintain legacy networks. The collection of infrastructure changes run from the radio access network (RAN) to mobile backhaul, evolved packet core, transport core and the data center.

This is the first of a series of articles on the coming changes in the mobile network, and what it means for users, providers, device makers and for the design and test engineers that have to make it all work.

The articles will provide a quick tech overview and cover the business drivers and challenges, occasionally digging deeper, especially in the areas of test and measurement. Topics planned include (and we’ll take suggestions for more):

  • Evolved Packet Core
  • IP Core Networks
  • Mobile Backhaul
  • Data Center
  • LTE Devices
  • Applications

Evolved Packet Core

The Evolved Packet Core (EPC) is the new mobile core designed to connect the high-speed access provided by LTE.  EPC provides session, mobility and Quality of Service (QoS) management for high-performance access to applications on the Internet and on corporate networks.

The EPC is needed to address requirements of a true mobile broadband experience expected by users and required by businesses. And the EPC could significantly reduce the cost of ownership for operators with fixed and mobile broadband services. But network equipment and system implementations need to be tested to verify that they meet the user quality expectations and that they deliver the new applications and new revenue models needed to grow and compete.

Mobile Backhaul & Evolved Packet Core

 

Unified IP

In 2G and 3G, voice and data employed different sub-domains from the device to the core: circuit-switched for voice and packet switched for data. LTE is end-to-end IP from devices through base stations to the core and into applications. Voice in LTE will be Voice over IP (VoIP).

EPC Components

The EPC includes the following major components:

The Serving Gateway provides the data connection between the radio network and the packet data network (PDN) and maintains paths to the PDN as user devices move between nodes in the radio access network (RAN).

The Packet Data Network Gateway provides the connection to the PDN and provides policy enforcement, packet filtering and charging provisions.

Within the EPC, the Mobility Management Entity provides signaling and control to manage user device access, session management, resources and mobility tracking for roaming and handovers.

Read more technical details and about the other components of the EPC on Wikipedia.

Challenges

The advances in devices, radios, and spectrum use along with the new business potential of the applications that can be enabled over IP mean that the EPC must address a number of challenges including:

  • An IPv6 strategy for coordination with and migration from IPv4
  • End-to-end QoS and QoE meeting or exceeding circuit switched for VoIP
  • End-to-end security for data and control planes
  • Interoperability with existing external network infrastructures
  • User mobility between 2G, 3G and LTE
  • Support high subscriber capacity in dense areas
  • Support application-aware features like deep-packet inspection, content filtering and billing at scale

EPC Testing

Testing core devices themselves and the end-to-end capabilities of an implementation requires realistic traffic generation and analysis to:

  • Verify interoperability between network elements across 2G/3G and 4G/LTE
  • Emulate millions of mobile subscribers in various stages of activation, deactivation, and hand-off between cells
  • Test simultaneous access to the wireless network using various access models while transmitting real-world application data
  • Test any node in the wireless packet core by emulating all adjacent nodes
  • Exercise complex mobility and load scenarios
  • Prove end-to-end security and application-aware features
 
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