In an Option 2 deployment, when additional capacity is required, what is the best solution?

In a 5G Standalone (SA) Option 2 deployment, the network operates with a 5G Core (5GC) and 5G New Radio (NR). When additional capacity is needed, Dynamic Spectrum Sharing (DSS) is an optimal solution. DSS allows a mobile operator to use the same frequency band for both 4G LTE and 5G NR services by dynamically allocating spectrum resources between the two technologies based on real-time user demand. This enables the operator to leverage its existing LTE spectrum holdings to boost 5G capacity without needing to re-farm the entire band, which would be disruptive to 4G users. It provides a smooth and efficient path to expand 5G capacity.

A. Carrier aggregation for 4G cells: This feature increases capacity for 4G users connected to the LTE network and does not directly add capacity for a user operating in a 5G SA (Option 2) mode.
C. Dual connectivity: This is the foundational architecture for 5G Non-Standalone (NSA, Option 3x) deployments, where a device connects to both a 4G eNB and a 5G gNB simultaneously. It is not the primary method for adding capacity to an existing SA network.
D. Carrier aggregation for 5G cells: While this is a valid method to increase 5G capacity, it requires the operator to have multiple, separate blocks of spectrum dedicated to 5G NR, which may not be available. DSS is often preferred as it utilizes existing spectrum assets.

1. Nokia Official Documentation: Nokia's solution description for Dynamic Spectrum Sharing explicitly states its applicability for both NSA and SA deployments. It notes, "Our DSS solution can be software-upgraded on all our existing FDD radios... It supports all 3GPP-defined spectrum sharing methods for NSA and SA, giving you maximum flexibility." This confirms DSS as a viable capacity solution for Option 2 (SA).

Source: Nokia, "Nokia Dynamic Spectrum Sharing solution," Solution Page. (Accessed via official Nokia public website).

2. Peer-Reviewed Academic Publication: A comprehensive survey on DSS highlights its role in SA deployments. The paper explains that DSS enables operators to deploy 5G SA in lower frequency bands already used by LTE, thereby improving 5G coverage and capacity efficiently. It states, "In SA mode, the UE connects directly to the 5G core network... DSS can be used to share the spectrum between LTE and NR carriers in the same band."

Source: Al-Samman, A. M., et al. (2022). "Dynamic Spectrum Sharing for 5G and Beyond: A Survey." IEEE Access, vol. 10, pp. 56170-56205, Section IV-A "DSS in SA Mode". DOI: https://doi.org/10.1109/ACCESS.2022.3177221.

3. Vendor Technical White Paper: Industry-wide documentation describes DSS as a key tool for spectrum management. It allows for the introduction of 5G NR in existing LTE bands, which is crucial for achieving a balance between providing service to legacy 4G devices and offering enhanced capacity for new 5G devices in both NSA and SA modes.

Source: Ericsson, "Ericsson Spectrum Sharing," White Paper, June 2021, Page 4, "Ericsson Spectrum Sharing in brief".