Many early 5G networks will start with option 3 NSA. The primary advantage of this solution is that 4G EPC network architecture may be used, only up-gradation is required. Option 2 SA will be an option for the early 5G deployment by service providers. Deployment of option 2 involves the introduction of a new 5G core network functions and 5G NR base stations and will avoid the need to rebuild the EPC core and minimizes changes to LTE eNB. Initial option 2 deployments using TDD bands above 3GHz is mainly considered for a dense urban area to provide capacity relief. The solution will be able to support native 5G services offered by the new 5G core network with inter-RAT handover used to maintain the connection when moving out of the 5G coverage area.
- Option 5 provides the “enhanced” LTE (e LTE) extensions to independentlyLTE access to support the introduction of native 5GC service across the network’s entire LTE coverage zone.
- Option 7 extends option 5 to offer NSA dual connectivity under an e LTE master carrier.
- Option 4 extends option 2 to offer NSA dual connectivity under an NR master carrier.
New cloud-native core network nodes supporting both EPC and 5GC network functions deployed using both virtual as well as physical implementations. LTE eNB and NR gNB nodes based on cloud RAN technologies linked together using open X2 and Xn interfaces. Orchestration tools in place to manage the overlay of different deployment options.
In this, LTE cell and NR cells provide similar coverage e.g if LTE and NR are operating on the same frequency band.
In this, LTE and NR cells are of different sizes. NR cells are large to meet the coverage requirements and LTE cells are of small size to meet the capacity requirements.
LTE eNB is a master node
In this, LTE eNB will act as a master node and NR gNB will act as a secondary node. All signaling processes are done by the master node.
gNB is a master node:
In this, NR gNB will act as a master node and LTE eNB will act as a secondary node. All signaling processes are done by the master node.
Individual RAT with inter mobility
In this network topology, both LTE and NR radio access networks are connected to their respective core networks independently. There is mobility across RAT.
Interworking with WLAN
When NR is fully capable of operating in SA mode, its functionality could be extended to WLAN for Wi-Fi offloading, etc.