5G: What is Standalone (SA) vs Non-Standalone (NSA) Networks?

According to the recent 3GPP Release 15 standard that covers 5G networking, the first wave of networks and devices will be classed as Non-Standalone (NSA), which is to say the 5G networks will be supported by existing 4G infrastructure. Here, 5G-enabled smartphones will connect to 5G frequencies for data-throughput improvements but will still use 4G for non-data duties such as talking to the cell towers and servers.

The initial roll-out of 5G cellular infrastructure will focus on enhanced mobile broadband (eMBB) to provide increased data-bandwidth and connection reliability via two new radio frequency ranges:

Frequency Range 1 overlaps and extends 4G LTE frequencies, operating from 450 MHz to 6,000 MHz. Bands are numbered from 1 to 255 and this is commonly referred to as New Radio (NR) or sub-6GHz.

Frequency Range 2 operates at a much higher 24,250 MHz (~24GHz) to 52,600 MHz (~52GHz). Bands are numbered from 257 to 511 and this is commonly referred to as millimeter wave (mmWave), even though strictly speaking the ‘millimeter’ frequency length starts at 30 GHz.

Not all of the large frequency range above will be used as available frequency zones differ between countries, so different sub-slices will be available depending on where the device operates. This has posed a huge technical challenge for smartphone design (or specifically, 5G modem designers), that have to minimize design costs with a single, simple platform, while also supporting all the possible combinations of frequencies with best performance, connection reliability and power efficiency.

The 5G Standalone (SA) network and device standard is still under review and is expected to be signed-off by 3GPP this year. The advantage of Standalone is simplification and improved efficiency, which will lower cost, and steadily improve performance in throughput up to the edge of the network, while also assisting development of new cellular use cases such as ultra-reliable low latency communications (URLLC). Once the SA standard is approved this year, the eventual migration from 5G NSA to SA by operators should be invisible to the user.