Error: Mac::fromPhy(): Received feedback for an unexisting H-ARQ tx buffer

[shashini-w]

Hello!

I am running a simulation with 39 GNBs and variable number of UEs (The UEs are added dynamically to the simulation environment). The simulation time is set to a time window of 2000s since the beginning of dynamic spawning of UEs. UE are mobile and periodically (2s) sending a message to a static control station (INET standard host). Transport layer is UDP. Number of RBs is 250 and the numerology index is set to 0. The simulation runs perfectly fine with the same conditions when I try to send a message of size 40 bytes.

Now I am trying to send a larger message of size varying between 130-150 KB. I am segmenting the message already in the sender app to packets of size 1000 bytes each. When I run simulations with this, sometimes after around 1000s have passed, the simulation crashes with the following error :

Finished with Error
<!> Error: Mac::fromPhy(): Received feedback for an unexisting H-ARQ tx buffer -- in module (NRMacUe) TestSplit.Agent76.cellularNic.nrMac (id=10548), at t=40865.4565s, event #6578404320

I am working wth OMNeT++ 6.0, INET 4.4.1 and Simu5G 1.2.1

It had occured to me that this error occurs when there are large number of UE s in the simulation environment. But it doesn't happen always. For example I'm running multiple simulation runs (10). At the end of the batch, around 3 simulations have failed with this error.

What is the cause of the error? Does the packet size or channel bandwidth has an effect on this? How to rectify this issue?