openWNS WiFiMAC

Questions regarding the output of the simmulation

Asked by Nikola

Hello!

I have some questions regarding the output files after running a WiFiMAC simmulation.

1. In the wifimac.e2e.packet.incoming.delay_dl_PDF.dat file, I get e.g. the following results:

# PROBE RESULTS (THIS IS A MAGIC LINE)
# ---------------------------------------------------------------------------
# Evaluation: PDF
# ---------------------------------------------------------------------------
# Name: no name available
# Description: no description available
# ---------------------------------------------------------------------------
# Evaluation terminated successfully!
# ---------------------------------------------------------------------------
# Common Statistics
# Minimum: 0.0142010
# Maximum: 0.0168737
# Trials: 9530
# Mean: 0.0154891
#
# Variance: 0.0000003
# Relative variance: 0.0014185
# Coefficient of variation: 0.0376628
# Standard deviation: 0.0005834
# Relative standard deviation: 0.0376628
#
# Skewness: -0.0003606
#
# 2nd moment: 0.0002403
# 3rd moment: 0.0000037
#
# Sum of all values: 147.6115482
# (Sum of all values)^2: 2.2896195
# (Sum of all values)^3: 0.0355647
# -----------------------------------------------------------
# PDF statistics
# Left border of x-axis: 0
# Right border of x-axis: 0.1
# Resolution of x-axis: 100
# -----------------------------------------------------------
# PDF data
# Underflows: 0
# Underflows in percent: 0
# Overflows: 0
# Overflows in percent: 0
# -----------------------------------------------------------
# Percentiles
# P01: 0.0140392
# P05: 0.0141962
# P50: 0.0154910
# P95: 0.0166960
# P99: 0.0168381
# -----------------------------------------------------------
#
# x_n F(x_n) G(x_n) P(x_n-1 < X n
# =P(X<=x_n) =P(X>x_n) AND X <= x_n)
#
0.0000000 0.0000000 1.0000000 0.0000000 0
0.0010000 0.0000000 1.0000000 0.0000000 1
0.0020000 0.0000000 1.0000000 0.0000000 2
0.0030000 0.0000000 1.0000000 0.0000000 3
0.0040000 0.0000000 1.0000000 0.0000000 4
0.0050000 0.0000000 1.0000000 0.0000000 5
0.0060000 0.0000000 1.0000000 0.0000000 6
0.0070000 0.0000000 1.0000000 0.0000000 7
0.0080000 0.0000000 1.0000000 0.0000000 8
0.0090000 0.0000000 1.0000000 0.0000000 9
0.0100000 0.0000000 1.0000000 0.0000000 10
0.0110000 0.0000000 1.0000000 0.0000000 11
0.0120000 0.0000000 1.0000000 0.0000000 12
0.0130000 0.0000000 1.0000000 0.0000000 13
0.0140000 0.0000000 1.0000000 0.0000000 14
0.0150000 0.2548793 0.7451207 0.2548793 15
0.0160000 0.7541448 0.2458552 0.4992655 16
0.0170000 1.0000000 0.0000000 0.2458552 17
0.0180000 1.0000000 0.0000000 0.0000000 18
0.0190000 1.0000000 0.0000000 0.0000000 19
0.0200000 1.0000000 0.0000000 0.0000000 20
0.0210000 1.0000000 0.0000000 0.0000000 21
0.0220000 1.0000000 0.0000000 0.0000000 22
0.0230000 1.0000000 0.0000000 0.0000000 23
0.0240000 1.0000000 0.0000000 0.0000000 24
0.0250000 1.0000000 0.0000000 0.0000000 25
0.0260000 1.0000000 0.0000000 0.0000000 26
0.0270000 1.0000000 0.0000000 0.0000000 27
0.0280000 1.0000000 0.0000000 0.0000000 28
0.0290000 1.0000000 0.0000000 0.0000000 29
0.0300000 1.0000000 0.0000000 0.0000000 30
0.0310000 1.0000000 0.0000000 0.0000000 31
0.0320000 1.0000000 0.0000000 0.0000000 32
0.0330000 1.0000000 0.0000000 0.0000000 33
0.0340000 1.0000000 0.0000000 0.0000000 34
0.0350000 1.0000000 0.0000000 0.0000000 35
0.0360000 1.0000000 0.0000000 0.0000000 36
0.0370000 1.0000000 0.0000000 0.0000000 37
0.0380000 1.0000000 0.0000000 0.0000000 38
0.0390000 1.0000000 0.0000000 0.0000000 39
0.0400000 1.0000000 0.0000000 0.0000000 40
0.0410000 1.0000000 0.0000000 0.0000000 41
0.0420000 1.0000000 0.0000000 0.0000000 42
0.0430000 1.0000000 0.0000000 0.0000000 43
0.0440000 1.0000000 0.0000000 0.0000000 44
0.0450000 1.0000000 0.0000000 0.0000000 45
0.0460000 1.0000000 0.0000000 0.0000000 46
0.0470000 1.0000000 0.0000000 0.0000000 47
0.0480000 1.0000000 0.0000000 0.0000000 48
0.0490000 1.0000000 0.0000000 0.0000000 49
0.0500000 1.0000000 0.0000000 0.0000000 50
0.0510000 1.0000000 0.0000000 0.0000000 51
0.0520000 1.0000000 0.0000000 0.0000000 52
0.0530000 1.0000000 0.0000000 0.0000000 53
0.0540000 1.0000000 0.0000000 0.0000000 54
0.0550000 1.0000000 0.0000000 0.0000000 55
0.0560000 1.0000000 0.0000000 0.0000000 56
0.0570000 1.0000000 0.0000000 0.0000000 57
0.0580000 1.0000000 0.0000000 0.0000000 58
0.0590000 1.0000000 0.0000000 0.0000000 59
0.0600000 1.0000000 0.0000000 0.0000000 60
0.0610000 1.0000000 0.0000000 0.0000000 61
0.0620000 1.0000000 0.0000000 0.0000000 62
0.0630000 1.0000000 0.0000000 0.0000000 63
0.0640000 1.0000000 0.0000000 0.0000000 64
0.0650000 1.0000000 0.0000000 0.0000000 65
0.0660000 1.0000000 0.0000000 0.0000000 66
0.0670000 1.0000000 0.0000000 0.0000000 67
0.0680000 1.0000000 0.0000000 0.0000000 68
0.0690000 1.0000000 0.0000000 0.0000000 69
0.0700000 1.0000000 0.0000000 0.0000000 70
0.0710000 1.0000000 0.0000000 0.0000000 71
0.0720000 1.0000000 0.0000000 0.0000000 72
0.0730000 1.0000000 0.0000000 0.0000000 73
0.0740000 1.0000000 0.0000000 0.0000000 74
0.0750000 1.0000000 0.0000000 0.0000000 75
0.0760000 1.0000000 0.0000000 0.0000000 76
0.0770000 1.0000000 0.0000000 0.0000000 77
0.0780000 1.0000000 0.0000000 0.0000000 78
0.0790000 1.0000000 0.0000000 0.0000000 79
0.0800000 1.0000000 0.0000000 0.0000000 80
0.0810000 1.0000000 0.0000000 0.0000000 81
0.0820000 1.0000000 0.0000000 0.0000000 82
0.0830000 1.0000000 0.0000000 0.0000000 83
0.0840000 1.0000000 0.0000000 0.0000000 84
0.0850000 1.0000000 0.0000000 0.0000000 85
0.0860000 1.0000000 0.0000000 0.0000000 86
0.0870000 1.0000000 0.0000000 0.0000000 87
0.0880000 1.0000000 0.0000000 0.0000000 88
0.0890000 1.0000000 0.0000000 0.0000000 89
0.0900000 1.0000000 0.0000000 0.0000000 90
0.0910000 1.0000000 0.0000000 0.0000000 91
0.0920000 1.0000000 0.0000000 0.0000000 92
0.0930000 1.0000000 0.0000000 0.0000000 93
0.0940000 1.0000000 0.0000000 0.0000000 94
0.0950000 1.0000000 0.0000000 0.0000000 95
0.0960000 1.0000000 0.0000000 0.0000000 96
0.0970000 1.0000000 0.0000000 0.0000000 97
0.0980000 1.0000000 0.0000000 0.0000000 98
0.0990000 1.0000000 0.0000000 0.0000000 99
0.1000000 1.0000000 0.0000000 0.0000000 100
# -----------------------------------------------------------

The CDF function looks some kind strange with these values and doesn't show a typical a CDF-curve.
Is the CDF implementation of the results working properly or are there any problems with that?
Could this has something to do with the load of the system? I use the default load in the config.py (6.0e6). Is it possible to change somewhere the PHY load of system?

2. What is meant by the MAC.CompoundSourceAddress, MAC.CompoundTargetAddress and the MAC.CompoundMCS in the *.m output files, e.g. in wifimac.linkQuality.sinr_mean.m?

3. What is meant by the "aggregated" output files, e.g. wifimac.e2e.window.aggregated.bitThroughput.hop_mean.m?
I never have values in these files, they are always empty! Is this due to a bug?

Thanks in advance for your answers!

Best regards,
Nikola

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Sebastian Max (smx-comnets) said : 		#1

Hi,

Regarding Question 1:

The file is perfectly correct; it contains (i) several statistical measures (mean, variance, max, min, etc.), and (ii) a table that consists of 5 columns:
1. The left boundary of the bin of the pdf, x_n
2. The CDF value of this bin, i.e., F(x_n) = P(X <= x_n)
3. The cumulative CDF value of this bin (which is equal to 1-F(x_n))
4. The probability of this bin, i.e., P(x_n-1 < X AND X <= x_n)
5. The number of the bin.
According to the file you submitted, the CDF stays at zero until 0.014 and rises to 1.0 at 0.017. Why is this not typical for a CDF? Could you specifiy your question 1?

To change the traffic load, simply vary the offeredDL parameter in the config.py. Obviously, 6Mb/s / 1480B packets using 'ConstantLow' as Rate adaptation is a overload simulation for IEEE 802.11a, as the file ip.endToEnd.window.incoming.bitThroughput_mean.m confirms (incoming IP-throughput is slightly above 5Mb/s).

Revision history for this message
Sebastian Max (smx-comnets) said : 		#2

Regarding Question 2:

MAC.CompoundSourceAddress: The source address of the compound, as written in the IEEE 802.11 MAC header
MAC.CompoundTargetAddress: The target address of the compound, as written in the IEEE 802.11 MAC header
MAC.CompoundMCS: The Modulation- and Coding Scheme ID that was used to transmit the compound

Revision history for this message
Sebastian Max (smx-comnets) said : 		#3

Regarding Question 3:

For incoming / outgoing / aggregated traffic measurements, the following example should make things clear:

STA1 <-> AP <-> STA2

Two STAs, one AP, uplink and downlink traffic. Probe measurements (for example) at the AP:

incoming: The traffic that was generated by either one of the STAs and has reached the AP
outgoing: The traffic that leaves the (layer where the probe is situated of the) AP
aggregated: The traffic that leaves the AP AND reaches successfully its destination

Revision history for this message
Nikola (nkz) said : 		#4

Hi!

Thanks yoi very much for the answers!

1. The "problem" with the CDF was fixed by increasing the resolution of the output and setting up a new maxValue for the output. In that was I was able to get nice curves.

2., 3.: It is now clear!

Best regards from Bremen,
Nikola