Throughput limitations when using Simu5G for real-time simulation

[zy-jack]

Hello,

I'm using the extclientserver example code in the emulation provided by Simu5G for simulation. No matter how I adjust the carrierFrequency and numBands parameters, the simulated throughput doesn't improve. Specifically:

When the carrierFrequency is set to 3.5GHz and numBands is set to {30, 40, 50, 60}, the throughput for both the receiver and transmitter is only 20Mbps when using iperf3 in TCP mode; when using iperf3 in UCP mode, the throughput is only 35Mbps; and when the carrierFrequency is set to 4.9GHz, the throughput remains essentially unchanged.

When the carrierFrequency is set to 3.5GHz and numBands is set to {80, 90, 100}, the throughput for both the receiver and transmitter is only 17Mbps when using iperf3 in TCP mode; when using iperf3 in UCP mode, the throughput is only 30Mbps; and when the carrierFrequency is set to 4.9GHz, the throughput remains essentially unchanged.

Is the throughput of Simu5G limited when performing real-time simulation?

[eseglo]

There are many potential causes. The throughput is quite sensitive to the number of harqProcesses you use. By the way, they are hard coded in LteCommon.h. It is also sensitive to targetBler and blerShift. But, it may be also because of the iperf configuration. For instance, in the example the MSS is limited to 536B. If you do set it to a higher values (for instance 1400), you need to increase the MTU of the veth and sim-veth interfaces or nothing is sent. Moreover, I assume you are using the UM mode, which is unacknowledged, and you may be having many lost packets, which are going to affect TCP. Try placing the UE closer to the GNB and see what happens.