Packet Loss confusion in LTE stats and Flow Monitor .

[Zoraze Ali]

Hi Everyone,

I have stats for LTE 20 ue scenario, in which every ue is tx and rx to and from each other respectively. I got the following stats:

DL PDCP : Total PDU Transmitted  = 1200 , DL PDCP : Total PDU Received = 1199

DL RLC Total PDU Transmitted = 1190 , DL RLC Total PDU Received = 1193

UL PDCP Total PDU Transmitted = 1249 , UL PDCP Total PDU Received = 1187

UL RLC Total PDU Transmitted = 1188 , UL RLC Total PDU Received = 1152

As explained by Nicola in this discussion ( https://groups.google.com/forum/?hl=en&fromgroups=#!searchin/ns-3-users/asif/ns-3-users/2VQK0QRO63g/tG09lxYKGqgJ )

There is an RLC instance at the eNB and another at the UE. So, for downlink:

- transmitted means delivered by the eNB RLC instance to the eNB MAC
- received means received by the UE RLC instance from the UE MAC

 * As in my highlighted DL RLC stats which is confusing in sense that  eNB RLC is transmitting 1190 PDU to eNB MAC in downlink then how it is possible that UE RLC is receiving 1193 PDU from UE MAC.



and according to flow monitor Total transmitted packets are 1249 and Received are 1200 ;  and LOST packet is 1.

can anyone please explain me above  LTE stats behavior and secondly i am wondering where 48 packets gone in flow monitor Loss ?

Regards,
Zoraze

[Nicola Baldo]

Can you please post the DlRlcStats and DlMacStats files?

[Zoraze Ali]

Hi Nicola ,

Thanks for the reply , attached are the DlRlcStats and DlMacStats files, in RLC i have just sum up all the transmitted and received PDUs to give above stats .

Regards,
Zoraze

[Nicola Baldo]

Thanks Zoraze for the files.
It looks like a bug, I've filed a report on the ns-3 bugzilla:
https://www.nsnam.org/bugzilla/show_bug.cgi?id=1630

I've been doing some investigation to understand the possible cause, but so far it is still unclear. Please see the above bug report for details.
Any help in investigating this issue would be appreciated!

[Zoraze Ali]

Hi Nicola ,

Thanks for your time to look at this issue , i will certainly gonna look for its solution mean while i have one more question about the FlowMonitor . For the same case we were collecting some stats from FlowMonitor which are as follows ,

Total Number of Ues= 20
Total Delay  = 24.1277 Sec
Average Delay Per Flow = 0.0603191 Sec
Total Transmit Packets in all Flows = 1329
Total Receive Packets in all Flows = 1280
Total Lost Packets in all Flows = 1
**************************************
Average Delay Per Packet of Run 16 = 18.8497 msec
Total Packet Loss Ratio of Run 16 = 0.00078064
**************************************

As according to this only 1 Packet is lost during all flows . But Total Packet Transmitted was 1329 and Total Received are 1280 . So as due to that Bug should we believe on these stats from flowmonitor .

I am attaching the XML file from Flowmonitor .

Regards,
Zoraze
 

[saumil shah]

Dear Nicola,

First of all sorry to post on this very old thread. But i have found the same issue.

I am working on ns-3-lbt module. I am also facing the problem of more Rx PDUS (717) than Tx PDUS (713) in RLC stats file.
Even I have replaced radio-bearer-stats-calculator.cc file in ns-3-lbt module with file from ns-3-dev module to make sure. As in the above mentioned bug report it mentioned that this issue is solved but i am still getting the same issue.

Even i have found some other threads to which are for same issue but there i didn't find any solution. I have tried changing Epochduration too but still problem exists.

Can you please help me with it?

For reference i have attached the RlcStats file too.

Best Regards
Saumil Shah