backup
The 8 options are divided into two groups: Standalone (SA) and Non-Standalone (NSA). In SA mode, only one radio access technology is used, either LTE or NR. Both control and user planes go through the same RAN element. This mode simplifies the deployment and network management, but requires inter-RAT handover for service continuity. In NSA mode, multiple radio access technologies are combined. Control plane goes through the master node, while data plane is split across the master and secondary nodes. This mode enables tight interworking between 4G RAN and 5G NR, but introduces more complexity and latency.
Two categories comprise these eight options: SA modes (Standalone) and NSA modes (Non-Standalone). The NSA modes are options 3, 4, 7, and 8, and the SA modes are options 1, 2, 5, and 6. Sub-options for options 3, 4, and 7 are also distinct.
Of these, Option 1 has already been integrated into the 4G structure; on the other hand, Option 6 and Option 8 are merely hypothetical deployment scenarios that have no real-world application and will not be taken into account in the standard.
Let us address each of them individually, beginning with SA modes.
The architecture of Option 1, which is a pure 4G networking architecture, is depicted in the above figure.
Between the phone, 4G base station, and 4G core network, you can see that there are solid and dashed lines. The user plane is represented by the solid line, and the control plane is shown by the dashed line.
Control plane: the channel used to transmit the signals needed for resource scheduling and management.
User plane: the data transmission channel for users. There is no connection between the control plane and the user plane.
Option 1 is not related to 5G.
Option 2 is depicted in the above figure. The design is extremely straightforward: a 5G base station is linked to a 5G core network, the pinnacle of 5G network architecture, which is capable of supporting all 5G services.
Despite the straightforward architecture, a significant number of new base stations and a core network must be constructed, which will come at a high cost to build such a 5G network.
Option 5 is depicted in the above figure. As you can see, this is essentially a 4G base station that has been upgraded and is connected to the 5G core network. On the other hand, the original 4G core network should be gradually phased out after the new 5G core network is constructed. Therefore, 4G base station architecture will also emerge as it will undoubtedly be required to connect the 5G core network.
In terms of peak rate, delay, and capacity, the upgraded 4G base stations still clearly differ from 5G base stations. Regarding further evolution and optimization, improved 4G base stations might not be able to accommodate. Therefore, Option 5 architecture’s future is also not promising.
Linking 5G base stations to the 4G core network is Option 6. Hardly any of the 5G base station power can be utilized by this option. It’s not really a reasonable decision to trade a significant investment for a negligible return, given that 5G base stations already require a larger financial commitment than 5G core networks. Consequently, no carrier will select this architecture, and 3GPP has no intention of standardizing it.
In conclusion, the only SA modes of 5G are Option 2 and 5, with Option 2 being the network’s ultimate architecture.
The following are SA Option 2’s benefits:
1. The quickest path to the ultimate 5G network will be taken by introducing 5G base stations and 5G core networks simultaneously, independent of the current 4G network.
2. The all-new features and services offered by the 5G network can be supported by the brand-new 5G base station and 5G core network.
In the meantime, SA Option 2 has the following drawbacks:
1. Because 5G networks have higher frequencies than LTE, it will be challenging to provide continuous coverage during initial deployment. As a result, there will be a lot of switching between 5G and 4G networks, which will negatively impact user experience.
2. It is not possible to fully utilize the resources of the current 4G base station and the initial deployment costs are somewhat high.
Let’s now discuss NSA network modes. The trade-off for cost savings is that the architecture of NSA networking is generally far more complex than that of SA networking.
First, we define a few associated terms:
1. Dual connection: As the name implies, the phone can simultaneously download data and communicate with 4G and 5G networks. A master connection and a slave connection are usually present.
2. Control plane anchor: The base station in charge of the dual connection’s control plane is referred to as the control plane anchor.
3. Data split anchor: Where should the user’s data be split? It needs to be divided for transmission in the two paths of the dual connection. We refer to this place as the data split anchor.
The answers to the three questions are combined to determine the different options for 5G NSA networking.
Are the base stations connected to the 4G or 5G core?
Which 4G or 5G base station is transmitting the control signaling?
Is the data split anchor located at the core network, 5G base station, or 4G base station?
There are three distinct answers to the three questions: options 3, 7, and 4. Let us present them individually.
There are three parts to the Option 3 series: 3, 3a, and 3x. The data split anchor is where the difference is.
The anchor points of the control plane are all located in the 4G core, and the Option 3 series base station is connected to the 4G core network. It works well during the early stages of 5G deployment when there is limited 5G service and intermittent coverage. Its sole purpose is to support 4G wireless broadband.
The data split anchor for Option 3 is located on the 4G base station, as can be seen in the above figure. In other words, 4G is in charge of both controlling and managing the data as well as splitting it into two paths: one route sends the data directly to mobile devices, while the other route distributes the data to 5G base stations for delivery to mobile devices.
Software upgrades are necessary for the 4G base station to perform the heavy lifting, but even with that, handling all of the 5G traffic may prove to be too much of a challenge.
Because of this, Option 3 has not drawn much attention or support since it was first put forth.
NSA Option 3a
By locating the data split anchor on the 4G core network, which distributes user data to the 4G and 5G base stations, Option 3a improves things a little. Even though this is a much better option than option 3, the 4G core network would need to be significantly upgraded.
NSA Option 3x
The data split anchor is wisely placed on the 5G base station by Option 3x. By doing this, Option 3x leverages the quick speed and robustness of 5G base stations while avoiding making too many changes to the 4G base stations and 4G core network that are already in use. As a result, option 3x is now the industry standard for 5G NSA networking deployment and has gained widespread adoption.
In conclusion, the following are the benefits, drawbacks, and relevant situations of the Option 3 series:
The advantages of Option 3 for the NSA:
1. Its standardization completion time is the earliest.
2. A good user experience can be had while streaming because dual connections are supported and 5G coverage is not necessary.
3. Quick network setup, minimal investment, and small network changes.
The disadvantages of Option 3 for the NSA:
1. Low flexibility results from the requirement that 5G base stations and the current 4G base stations come from the same manufacturer in order for them to function together.
2. Unable to accommodate newly added features and services brought about by the 5G core network.
Relevant application for NSA Option 3:
To quickly offer high-value zones commercial 5G service. It is advised to choose option 3x.
Compared to the Option 3 Series, the Option 7 Series is one step closer to 5G. The 5G core is now the primary network in this series. The 4G base station has also been upgraded to an enhanced 4G base station in order to connect to the 5G core network.
The Option 7 series’ control plane anchor, however, is still on 4G, making it appropriate for 5G deployment in its early and intermediate phases. As of yet, the coverage is not nonstop. But now that 5G’s core network has been put into place, the other two services—mMTC and uRLLC—can also be supported in addition to the most basic mobile broadband.
With this option, 5G service capability is significantly increased, but 4G coverage is still required.
There are three subseries within the Option 7 series: 7, 7a, and 7x. These subseries are distinguished by the location of the data split anchor.
Option 7 is located in the enhanced 4G base station, Option 7a is located in the 5G core network, and Option 7x is located in the 5G base station. Option 7 is the data split anchor.
Both Option 7a and Option 7x are appropriate, though Option 7x is more common, much like the Option 3 series.
In conclusion, the following are the advantages, disadvantages , and relevant scenarios of the Option 7 series:
Advantages of Option 7 for the NSA:
1. We can make use of 4G coverage since 5G coverage is not necessary.
2. Support for dual connections enhances network performance and offers a positive user experience.
3. The introduction of the 5G core network enables the new 5G features and services.
Disadvantages of NSA Option 7:
1. Upgrading 4G base stations requires a significant amount of labor.
2. The industry may be maturing somewhat later than expected.
3. There is low flexibility because 5G base stations and upgraded 4G base stations have to be compatible, meaning they have to be made by the same manufacturer.
Situations where NSA Option 7 is applicable:
Enhanced 4G base stations provide continuous coverage in the early and mid phases of 5G deployment, while 5G is utilized for high-value zones to increase capacity. We advise selecting option 7x.
Let’s now discuss Option 4.
5G is fully front and center for this series. The 5G base station has taken over as the anchor point of the control plane, and the core network has already been converted to the 5G core.
Option 4 and Option 4a are divided into Option 4 Series. The only distinction between the two figures above is whether the data split anchor is located in the 5G core network or the 5G base station. As neither of these entails updating or changing out legacy hardware—both of these are new network components—both choices are reasonable.
The middle and late phases of 5G deployment correspond to the application scenario for the Option 4 series. As a supplement to 4G, 5G has achieved continuous coverage, fully displacing 4G.
Option 8
Option 8 will be obtained if you swap out the 5G core network in Option 4 for a 4G core network.
But 3GPP hasn’t thought about standardizing this option because it’s unreasonable to use the potent 5G base station as a control plane anchor beneath the 4G core network.
Following our discussion of the features, advantages, and disadvantages of 5G’s SA and NSA networking modes, the question of how to progress among so many architectures emerges.
Evolution can take two different routes.
Path 1: Select Option 2, the best architecture, right away. Starting out, a significant investment is needed for this.
Option 1 → Option 3x → Option 7x → Option 4 → Option 2 is the second path; all intermediate steps are optional.
Path 2 appears more complex, and the total cost of several investments is higher than the amount of a single investment. Still, there is less of a risk. Investing gradually could be a smart move.
Path 2 appears to be extremely complex due in large part to the transition from a 4G core to a 5G core. Fortunately, the 4G and 5G core networks can be combined to create a 4/5G fusion core network due to the gradual maturation of virtualization and cloud computing. This makes it much easier for wireless networks to evolve and allows for the peaceful coexistence of many network architectures.
All of this will actually be determined by one factor, and that is the explosive growth in demand for 5G.
