Application throughput variation with node mobility

Objective#

To simulate and analyze how application throughput varies as the node moves away. This analysis is done for 802.11n with Rate Adaptation set False.

Open NetSim and Select Examples->Mobile Adhoc Networks->Application Throughput Variation with Node Mobility then click on the tile in the middle panel to load the example as shown in below screenshot

Figure4-26

Rate Adaptation#

Three rate adaptation settings are available in NetSim.

  1. FALSE: This is similar to Receiver Based Auto Rate (RBAR) algorithm. In this, the PHY rate gets set based on the target PEP (packet error probability) for a given packet size, as given in the standard. The adaptation is termed as “FALSE” since the rate is pre-determined as per standard and there is no subsequent “adaptation”.
    a. 802.11 n/ac: Target PEP = 0.1, Packet Size: 4096 B
    b. 802.11 b: Target PEP = 0.08, Packet Size: 1024B
    c. 802.11 a/g/p: Target PEP:0.1, Packet size1000B
  2. GENERIC: This is similar to the Auto Rate Fall Back (ARF) algorithm. In this algorithm:
    a. Rate goes up one step for 20 consecutive packet successes.
    b. Rate goes down one step for 3 continuous packet failures.
  3. MINSTREL: Per the minstrel rate adaptation algorithm implemented in Linux

The following network diagram illustrates, what the NetSim UI displays when you open the example configuration file see Figure

Figure4-27

Settings done in the network:

  1. The device coordinates were set as follows:

    Device Name x- axis y-axis
    Wireless_Node_1 0 100
    Wireless_Node_2 60 100
  2. IEEE standard was set to 802.11n in Interface (Wireless)-> Physical layer of both the wireless nodes.

  3. The Physical layer properties were set as follows Table

    Interface Parameters
    Standard IEEE802.11n
    No. of Frames to aggregated 1
    Standard Channel 1 (2412MHz)
    Transmitting Antennas 1
    Receiving Antennas 1
    Guard Interval 400ns
    Bandwidth 20MHz
    Frequency Band 2.4GHz
    Transmitter Power 100mW
    Antenna Gain 0
    Antenna height 1m
    Reference distance (d0) 1m
  4. The Medium Access Protocol was set to DCF in Interface (Wireless)-> Datalink layer of both wireless nodes.

  5. Right click Wireless_Node_1 -> Network layer Enable Static IP Route and Configure Static Route IP as shown below screenshot

Figure4-28

  1. Rate Adaptation was set as False in Interface (Wireless) -> Datalink layer of both wireless nodes.
  2. Channel characteristics are set as: Path loss only; Path loss model: Log Distance; Path loss exponent: 3.
  3. The mobility model was set to No Mobility in Wireless_Node_1 and File_Based_Mobility inWireless_Node_2.
  4. Unicast CBR application was configured from Wireless_Node_1 to Wireless_Node_2 with packet size 1460 bytes and Inter Arrival Time 389.3 microseconds, which gives a Generation Rate of 30 Mbps.
  5. Set application start time as 0 sec.
  6. The Transport protocol was set to UDP.
  7. Enable plots and run simulation for 20 seconds.

File based mobility code:
#
#nodes: 2 max x = 500.0, max y: 500.0
#
$node_(0) set X_ 00.0
$node_(0) set Y_ 100.0
$node_(0) set Z_ 0.0
$node_(1) set X_ 60.0
$node_(1) set Y_ 100.
$node_(1) set Z_ 0.0
$time 0.0 "$node_(1) 60.0 100.0 0.0"
$time 1.0 "$node_(1) 70.0 100.0 0.0"
$time 2.0 "$node_(1) 80.0 100.0 0.0"
$time 3.0 "$node_(1) 90.0 100.0 0.0"
$time 4.0 "$node_(1) 100.0 100.0 0.0"
$time 5.0 "$node_(1) 110.0 100.0 0.0"
$time 6.0 "$node_(1) 120.0 100.0 0.0"
$time 7.0 "$node_(1) 130.0 100.0 0.0"
$time 8.0 "$node_(1) 140.0 100.0 0.0"
$time 9.0 "$node_(1) 150.0 100.0 0.0"
$time 10.0 "$node_(1) 160.0 100.0 0.0"
$time 11.0 "$node_(1) 170.0 100.0 0.0"
$time 12.0 "$node_(1) 180.0 100.0 0.0"
$time 13.0 "$node_(1) 190.0 100.0 0.0"
$time 14.0 "$node_(1) 200.0 100.0 0.0"
$time 15.0 "$node_(1) 210.0 100.0 0.0"
$time 16.0 "$node_(1) 220.0 100.0 0.0"
$time 17.0 "$node_(1) 230.0 100.0 0.0"
$time 18.0 "$node_(1) 240.0 100.0 0.0"
$time 19.0 "$node_(1) 250.0 100.0 0.0"
$time 20.0 "$node_(1) 260.0 100.0 0.0"

Results#

Figure4-19

Inference#

We can see that the Application throughput drops from 25 Mbps to 20 Mbps at around 4 seconds (the distance at this time is 100 m), and then to 16.5 Mbps at 8 seconds (the distance at this time is 140 m) and to 14 Mbps at 10 seconds (the distance at this time is 160 m) and then to 10 Mbps at 13 seconds (the distance at this time is 190 m) and then to 6 Mbps at 16 seconds (the distance at this time is 220 m). Note that this was got when the path loss exponent, in the RF propagation model, was set to 3.0.