LTE LENA: question on the example lena-simple-epc.cc

[Dapeng Liu]

Hi,

I am studying lena-simple.epc.cc.

I made changes: simulation time 1s, UDP packet size 1000KB.

when 2 eNB distance is 0.5m, i have PDCP downlink trace:

% start end     CellId  IMSI    RNTI    LCID    nTxPDUs TxBytes nRxPDUs RxBytes delay   stdDev  min     max     PduSize stdDev  min     max
0       0.25    1       1       1       1       61      62902   3       3090    0.202332        0.0061101       0.196999        0.208999        1030    0       1030    1030
0       0.25    2       2       1       1       61      62902   3       3090    0.118999        0.004   0.114999        0.122999        1030    0       1030    1030
0.25    0.5     1       1       1       1       66      68076   4       4144    0.347749        0.0398443       0.288999        0.372999        1036    12      1030    1054
0.25    0.5     2       2       1       1       65      67022   2       2060    0.294999        0.00565685      0.290999        0.298999        1030    0       1030    1030
0.5     0.75    1       1       1       1       66      68052   3       3090    0.532999        0.0820731       0.448999        0.612999        1030    0       1030    1030
0.5     0.75    2       2       1       1       67      69106   5       5150    0.510199        0.048777        0.454999        0.550999        1030    0       1030    1030
0.75    1       1       1       1       1       66      68076   2       2060    0.738999        0.0537401       0.700999        0.776999        1030    0       1030    1030
0.75    1       2       2       1       1       65      67022   7       7210    0.640713        0.0774741       0.602999        0.815999        1030    0       1030    1030


when 2 eNB distance is 0.51m, i have PDCP downlink trace:

% start end     CellId  IMSI    RNTI    LCID    nTxPDUs TxBytes nRxPDUs RxBytes delay   stdDev  min     max     PduSize stdDev  min     max
0       0.25    1       1       1       1       115     119818  112     116680  0.0149995       0.00919113      0.00499906      0.029   1041.79 12.052  1030    1054
0       0.25    2       2       1       1       115     119818  112     116680  0.0156513       0.0100846       0.00499898      0.031   1041.79 12.052  1030    1054
0.25    0.5     1       1       1       1       126     131316  127     132370  0.0105743       0.0052747       0.00499906      0.021   1042.28 12.0442 1030    1054
0.25    0.5     2       2       1       1       126     131316  127     132370  0.0114562       0.00620181      0.00499898      0.021   1042.28 12.0442 1030    1054
0.5     0.75    1       1       1       1       126     131292  125     130238  0.00896753      0.00401644      0.00499906      0.013   1041.9  12.0479 1030    1054
0.5     0.75    2       2       1       1       125     130238  125     130238  0.00896749      0.00401648      0.00499898      0.013   1041.9  12.0479 1030    1054
0.75    1       1       1       1       1       124     129208  125     130262  0.00903154      0.00401644      0.00499906      0.013   1042.1  12.0479 1030    1054
0.75    1       2       2       1       1       125     130262  125     130262  0.00903149      0.00401648      0.00499898      0.013   1042.1  12.0479 1030    1054

Delay in two cases seem to be quite different. Does 0.01m matter this much? How is the inter-eNB interference handled in this case?


Thanks

[Manuel Requena]

Hi,

Apart from the distance between the 2 eNBs, what other parameters you use in your both simulations? The TxPDUs are also different and this depends on the configuration of the applications.
Could you send the simulation programs and the simulation parameters?

Best regards,
Manuel

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[Dapeng Liu]

Other than the distance between two eNBs, I did not change anything in the original lena-simple-epc.cc. All configurations have their default values.

I thought the results should change gradually with reducing inter-eNB distance, not very abruptly.

Please anybody can help?

Thanks,

[Nicola Baldo]

Hi Dapeng,

On Wednesday, May 16, 2012 6:11:49 PM UTC+2, Dapeng Liu wrote:

Other than the distance between two eNBs, I did not change anything in the original lena-simple-epc.cc. All configurations have their default values.

I agree with Manuel, you would not get so many PDUs if you were really using the default values.

Anyway, the inter-cell interference model is verified by a corresponding test suite, please refer to the corresponding section of the documentation for detailed info:
http://lena.cttc.es/manual/lte-testing.html#inter-cell-interference-tests

Nicola

[Vincenzo Rea]

Well, what I think about your problem is that the propagation model uses some thresholds; one of these is the distance between  the node A and B where A and B are the nodes that you're (ok, the simulator is) analyzing for getting the received power value. This threshold is set to 0.5m by default, under these distance you can have, as received power, the same value of your Tx power. 
This can explain you why, if you set 0.49m as the distance between the 2 eNBs, you will have results very close to the ones where 0.5m is (I hope it is).

[Nicola Baldo]

I confirm it's due to the propagation model, in particular due to FriisPropagationLossModel which is being used by lena-simple-epc.
I just filed a bug report on the ns-3 bugzilla to keep track of this issue:
https://www.nsnam.org/bugzilla/show_bug.cgi?id=1443

[Neville]

Hi Nicola,

Is it possible to have a communication between 2 UEs in this example ? or is there any other example that implement UE to UE communication + UE to eNB

Thanks,

[Nicola Baldo]

On Thursday, September 26, 2013 12:35:04 PM UTC+2, Neville wrote:

Is it possible to have a communication between 2 UEs in this example ? or is there any other example that implement UE to UE communication + UE to eNB

Neville, this question is irrelevant for this thread. Besides, I've already replied you in this other thread:
https://groups.google.com/d/msg/ns-3-users/rtGne6JAS8Y/WIgx8TzUopAJ