NR Carrier Aggregation: Throughput does not scale with number of CCs in cttc-nr-cc-bwp-demo

[Sai charan Padarthi]

Hello,

I am working with the NR module in ns-3.46 and using the example:

scratch/cttc-nr-cc-bwp-demo.cc

I am trying to evaluate throughput scaling when increasing the number of contiguous Component Carriers (CCs).

Experiment Setup:

• 1 gNB

• 1 UE

• TDD mode

• Round Robin scheduler (NrMacSchedulerTdmaRR)

• Default traffic configuration

• lambdaUll = 10000

• udpPacketSizeBe = 1252

• simTime = 1s

Observation:

When I run with:

numContiguousCcs = 4

and compare with:

numContiguousCcs = 1

The mean flow throughput remains approximately 102 Mbps in both cases.

From FlowMonitor output:

TxOffered ≈ 102 Mbps
Throughput ≈ 102 Mbps

My Understanding:

Since:

Throughput = min(Offered Load, Radio Capacity)

It appears the system is application-limited, not radio-limited.

Therefore increasing CCs does not increase throughput because:

Offered Load < Radio Capacity

My Question:

Is this the expected behavior of the NR module?

To observe scaling with CCs:

• Should the offered load exceed single-CC capacity?

•   Or is there something specific in the NR MAC scheduler or BWP mapping that limits scaling
  
  
  please answer clearly why throughtput is not increasing if the ccs are increasing   

[Gabriel Ferreira]

You need to configure the BWP manager to route 5QIs through other BWPs to observe this aggregation effect.