If you are struggling to figure out what 5G really is all about with New Radio, Network Slicing, Edge Computing and other cool novelties, you may also have heard of various “options” for 5G deployment. Like “we are mainly considering option 2 and 3, and we believe option 7 is superfluous”. But what are people actually talking about?
If you already know – that’s great! It means that you don’t have to read the rest of this article. Perhaps a coffee break instead? But if you don’t know about the various options, hopefully this text will explain what they are all about!
In short, these options describe different combinations of base stations (eNBs and gNBs) and core networks (Evolved Packet Core, EPC or 5G Core, 5GC). Obviously, an operator will not replace the 4G network (eNBs + EPC) with a 5G network (gNBs + 5GC) overnight! There will be a migration that can follow different paths.
Sometimes you’ll hear about Option 1 which oddly enough is not 5G at all. In fact, Option 1 is good old 4G with eNBs connected to EPC and it is there more as a reference or starting point.
Option 2 is more exciting! This refers to gNBs connected to the 5GC. True 5G if you will, with support for all the fancy 5G features and use cases. But still a little into the future at the time of writing this article.
Option 3 is likely to be the first 5G step for many operators. This means keeping the EPC and legacy eNBs, but adding gNBs in the radio network. Those gNBs add more New Radio (NR) capacity, but they cannot work on their own. The depend on having an eNB as a companion and for having a control plane connection to the core network This setup is therefore referred to as Non-Stand Alone (NSA) mode.
Option 4 is “the opposite” of Option 3. The core network is 5GC and in the radio network there are gNBs – but also eNBs in Non-Stand Alone mode meaning that they do not work on their own. They need to have a gNB as a companion.
Option 5 is a bit odd, perhaps? It is the 5GC but 4G eNBs in the radio network, although the eNBs have the new NG interface towards the 5GC. The use case for this might not be obvious, but maybe we can think of an operator who does not see an immediate need for more radio capacity but still wants to benefit from new functions in the 5GC e.g. better support for virtualization and network slicing?
Option 6 is easy – it does not exist! At least not anymore! Which brings us to…
Option 7! What combination is left? It is the 5GC with eNBs plus additional gNBs in NSA mode. Perhaps the operator in Option 5 realizes that more radio capacity is actually needed, and therefore adds gNBs in strategic places in the network.
Are the 5G Options clear?
Hmm, did anything become clearer? Perhaps a little? But actually, all the nice benefits we get from possible interworking between 4G and 5G come at a price in the shape of many deployment options and possibly some brain pain. But if you like crosswords and sudoku – you’ll enjoy 5G!