Disadvantage of 5G NR option 3A over 3X

5G NR
1

Hi All.

Can anyone tell what is the disadvantage of 5G NR option 3A over 3X?

Admin note: this post was updated with image below.

Option 3-3a-3x
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2

This can help:

3

I guess Excess load on LTE for option 3A, both SRB and DRB managed by LTE.

In 3X, signalling(SRB) will be done by master node LTE only, data will be split between LTE and NR from secondary node NR.

4

Data split will be in 3A as well but it will be managed by EPC.

What’s the disadvantage if that splits happen in EPC (3A) or through gNB PDCP (3X)?

How does it matter?

5

On 3a data spilt you can keep like this:

  • Dldataspilitthreholdinbytes infinity (blocking the data).
  • Dldataprimarypath Secondary cell group.

Where on 3x you can keep like this:

  • Dldataspilitthreholdinbytes (b100/or other value).
  • Dldataprimarypath Secondary cell group.
6

Why World deployed 3X not 3A?

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Robust coverage, peak data rate & good mobility with less latency…

8

Do we define 3A or 3X anything in RAN side?

9

The difference is that data going to the EPC is over S1 link which will have latency due to larger distance between site to Core.

But with 3x, the x2 link between 5G and 4G is like an internal short path which gives you the lower latency and low packet losses improving experience.

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10

We have x2u on 3x also, here gNB carry on most of the traffic and avoids excessive LTE upgradations.

11

So it’s a EPC configuration or RAN configuration?

Why RAN supplier is saying they don’t support 3A?

12

In 3A, frequent path switch can happen if NR coverage is not continuously good.

It increases signalling, delay and performance.

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  • 3 - hardware issue (MCG - eNB)
  • 3A - SCG (gNB) coverage issue (when TDD is there)
  • 3X - above 2 issues resolved with this option
14

Thanks… So, these are the disadvantages in 5G NR NSA Architectures Option 3 and 3A which led 3GPP to come up with Option 3X architecture.

15

please, why has SCG split been more preferred by industry? why can’t we use MCG split instead to avoid switching s1_u path every time 5g leg is being added?
thanks!

16

One potential disadvantage of option 3A compared to option 3X is that option 3A may not be able to provide the same level of capacity and coverage as option 3X due to the limitations of the sub-6 GHz frequency range. The mmWave frequency range has a much higher bandwidth available compared to the sub-6 GHz frequency range, which allows for higher data rates and more efficient use of the spectrum. As a result, option 3X may be able to provide significantly higher capacity and coverage than option 3A in certain scenarios.

Another potential disadvantage of option 3A is that it may be more susceptible to interference and signal degradation due to the higher penetration loss and higher absorption loss at the sub-6 GHz frequency range compared to the mmWave frequency range. This can affect the performance of the 5G NR network and may limit the use of option 3A in certain environments.

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17

yes,To support CA using option 3A or option 3X, certain configuration steps may be required on the radio access network (RAN) side. These may include:

Configuring the CA parameters: The CA parameters define the frequency bands that are used for CA, as well as the bandwidths and other characteristics of the bands. These parameters need to be configured in the RAN in order to enable CA using option 3A or option 3X.

Configuring the radio frequency (RF) parameters: The RF parameters, such as the transmitted power and the antenna configurations, need to be configured in the RAN in order to optimize the performance of the CA configuration.

Configuring the scheduling parameters: The scheduling parameters, such as the scheduling grant and the allocation and deallocation of resources, need to be configured in the RAN in order to control the data flow in the CA configuration.

Configuring the mobility parameters: The mobility parameters, such as the handover thresholds and the measurement configurations, need to be configured in the RAN in order to support smooth handovers and seamless service in the CA configuration.

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18

There are two main types of SCC configurations: standalone (SA) and non-standalone (NSA). In the NSA configuration, the SCC is used in conjunction with the legacy radio access technology (RAT), such as LTE, to provide 5G coverage and capacity.

The SCC can be split into two main components: the secondary component carrier group (SCG) and the secondary component carrier subgroup (SCSG). The SCG is used to support CA within a single frequency band, while the SCSG is used to support CA across multiple frequency bands.

The SCG split configuration is preferred by the industry over the multicarrier group (MCG) split configuration because it allows for a more flexible and efficient use of the spectrum. In the SCG split configuration, the SCC can be dynamically added or removed from the CA configuration based on the current traffic demand and other factors, which allows for a more efficient use of the spectrum and a better utilization of the available resources.

In contrast, the MCG split configuration requires a fixed allocation of the spectrum to the SCC, which may not be optimal in all scenarios. In addition, the MCG split configuration requires

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