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Mobile network modernization, the journey to 5G

On 5GC deployment and migration path options for MNOs

5G is the next generation of cellular mobile network. It’s a smart ecosystem that will provide a universal solution, low latency and the agility required for service providers to launch customized business services that will generate greater value.

In this blog I'll dive into technical details of the network modernization that are needed for a successful 5G transition.

5G Industry Requirements

The telco industry went ahead and specified three main use cases (also explained in Ditri Trio's blog on Network Slicing) to support the business requirements in the 5G future network:

  1. Enhanced Mobile broadband (eMBB): A faster network that reaches up to 10Gbps as peak data rate.
  2. Massive machine type communication (mMTC): Massive connectivity, reaching more than 100.000 devices per square kilometer.
  3. Ultra-reliable and Low latency applications (uRLLC): Aimed to reach less than 1ms latency for mission critical services.

Figure 1: Industry requirements for future proof networks

To be aligned with and to support the ITU IMT 2020 QoS requirements, IP networks including backhaul, midhaul and fronthaul, have to be designed and dimensioned taking into consideration CU+DU+RU scenario deployments and the spectrum used by the MNO. It’s very likely that Service Providers have multiple deployment scenarios because they will be operating in a wide spectrum such as: Mmwaves and RU+DU combinations or centralized radio deployment and CU+DU combined. These require different radio deployment strategies.

The summary here is that the 5G network needs to be built hand in hand with the IP planning and radio requirements.

3GPP and 5G Core Network integration

3GPP has defined both a new 5G core network, referred to as 5GC, as well as a new radio access technology called 5G ‘New Radio’ (NR). With 5G it is possible to integrate elements of different generations into different configurations, including:

  • Standalone using only one radio access technology and
  • Non-Standalone combining multiple radio access technologies.

5G Deployment Scenarios and architecture options

In September 2016 Deutsche Telecom created a viewpoint to show how many different architecture options are possible within a 5G ecosystem; they came up with eight options in total.  These are still considered as the gold standard and are now considered as industry norm.

The diagram below has further developed the Deutsche Telecom position. Additionally it has other options including 3x and 7x.

Figure 2: 5G Deployment scenarios

Mobile service providers are looking to monetize their investment by offering new 5G services and accelerate their time to market. Option 3x helps Service Providers to get started with 5G by leveraging their existing EPC core. In this option, the operators do not need a 5G Core.  In the early stages of 5G deployment, Option 3/3a/3x will be the likely choice for many operators.  As this approach is tied to LTE, it is important not to disrupt the existing network.  Operators have the option of deploying dual connectivity for data, like high throughput in NR downlink and best coverage in LTE uplink; meanwhile voice traffic will fully run on LTE. 

Option 3 represents a network having both LTE and NR radio access, while only using the EPC core of LTE to route the Control signals.  In this option, LTE is used as the control plane anchor for NR and both LTE and NR are used for user data traffic (user plane).

5GC deployment and migration path options for MNOs

To fully deploy a 5GC network from option 3, MNOs have many migration path options, such as the ones below and more:

  • NSA Option #3 to NSA Option #7 and SA Option #5
  • NSA Option #3 to NSA Option #3 and SA Option #2
  • NSA Option #3 to NSA Option #4 and SA Option #2

The variety of options and migration steps available for deploying 5G allow operators to adopt different strategies that suit the specific market situations, business models and competition challenges.

Walid Ansrah - 18 June 2019

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