[srslte-users] pdsch_enodeb example and different traffic patterns

[Andrés García Saavedra]

Hi SRSers,

I am trying to modify the pdsch_enodeb example to generate different
traffic patterns (rather than 100% data or getting that data from a socket).

The modification seemed pretty trivial: essentially tuning the bool
send_data variable at pdsch_enodeb.c true/false for every subframe
according to a pattern. However I am having performance issues at the
receiver's side.

As a use case, I am testing the following simple pattern based on a
variable int duty_cycle = {0,100}:
- I send data (send_data=true) for a number of subframes = duty_cycle;
- then, I do not send data (send_data=false) for a number of subframes =
100-duty_cycle.

For small MCS idx, everything works as expected, e.g. for MCS idx = 0 at
the UE I receive TBS*duty_cycle/100 kbps throughput (using iperf's TCP
server) -- and I see ~ (100-duty_cycle) PDCCH-Miss and low PDSCH-BLER.

However, for larger MCS idx (e.g. 17), the UE pops out many "*No space for
SSS/CP detection. Realigning frame*" messages and much lower throughput
than expected (and overly large PDCCH-Misses) when duty_cycle is < 100
(everything goes great when send_data is always true at the eNB).

I've checked that all reference signals are properly sent regardless if
send_data is false or true, so I am not sure what the problem may be. Any
pointer?

Thanks,
Andres
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