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There is much more to introducing 5G than simply deploying New Radio (NR) technology. For a successful 5G launch, the operator needs to secure a network platform, that includes end-to-end (E2E) capabilities aligned across devices, RAN, core and management systems.

Challenges for 5G

5G is a technology transformation for operators striving for more flexibility and speed in network deployment—and with an expectation of being able to address new business opportunities with use cases beyond mobile broadband (MBB).

Mobile network operators that deploy 5G must be able to support user equipment, radio network, core network and management products that are manufactured by a multitude of device and network equipment vendors. With multiple connectivity options,  there is a high risk that different operators will deploy different options, in a different order.

The complexity caused by a multitude of deployed connectivity options would also have an impact on the E2E testing of services in the operator network, including both existing services like voice as well as new ones. Further, the higher the number of options deployed, the more complex and time consuming it will be for the operator community to establish 5G roaming in the industry.

5G deployments options

To reduce complexity, and to provide direct steps leads toward the long-term target architecture, we will here focus on 3 deployment options:

  • Option 1 relies on existing LTE/EPC architecture.
  • Option 2 is the target architecture with stand-alone New Radio (NR) and 5G Core (5GC).
  • Option 3, called dual connectivity is the best short-term alternative for 5G deployment, as it relies on existing LTE/EPC (option 1) when connecting NR.

Option 2 can initially be deployed for specific use cases in local areas, where devices stay within good NR coverage, while option 3 provides reliable and smooth mobility based on anchoring in LTE/EPC, even if the NR coverage is spotty. It provides faster TTM for advanced 5G use cases, for example and minimized impact on existing network from start.

The use of dual connectivity (option 3) has, however, introduced some challenges on the UE side with dual transmitters, which, in some cases, will limit performance and coverage. One of the main drivers for going beyond option 3 is to provide 5GC-enabled capabilities like connecting user equipment to multiple network slices simultaneously, edge computing support and operational benefits, even though EPC can also support these services to some extent (slicing based on DECOR, for example).

Longterm, providing option 2 on wide area use cases like mobile broadband will typically require NR on 3.5GHz to be combined with NR on low band to provide continuous coverage in both the uplink and downlink.

Spectrum migration steps for the 5G network-1

Reducing complexity

In release 15, the 3GPP has defined multiple architectural options for a user equipment to connect to the network, including option 1, 2 and 3 above together with a number of other options, adding evolved LTE (eLTE) in a number of deployment options.

The industry has decided to base the initial deployment of 5G on options 3 and 2. While the other options may initially seem beneficial for specific operators’ deployment cases, it is important to recognize that none of them are direct steps leading toward the long-term target architecture, as they would add unnecessary complexity in the target architecture, in the interaction with other network functions.

In addition, substantial interoperability retesting between networks and user equipment would be required to ensure the operation of legacy features and services, and it would require substantial upgrades of the eNB software.

Further reading

To get more information on the different deployment options for 5G, and why we see option 2 and 3 as the best deployment options going forward to the 5G architecture download the latest Ericsson Technology review article "Simplifying the 5G ecosystem by reducing architecture options":

Download

Read more about how to be first in 5G, by getting first to the core network.

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Anders Hillbur
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Anders Hillbur

Anders Hillbur is External Communications Manager, handling media and analyst relations for Business Area Digital Services at Ericsson, promoting Ericsson’s next generation Cloud infrastructure, network virtualization and IP networks.