[Ns-developers] Problem with the Transmission Range using the WirelessPhyExt and 802_11Ext

[Tommy Huy Nguyen]

Hi,

I am using ~/ns-2.33/indep-utils/propagation/threshold.cc to figure out
the transmission range of wireless mobile nodes. I am also confirming
the transmission range in the TCL script by varying the distance between the
two mobile nodes. If I use the default values (tcl/lib/ns-default.tcl) in
the following modules then the transmission range is about 532.2m. If the
mobile nodes are not moving, then the transmission range is accurate.
However if they are moving, then something weird is going to happen.

*Format: (x-coordinate, y-coordinate, speed m/s)*

Node A: (607.078773, 460.093462, 1.108952)
Node B: (68.692986, 957.133042, 0.144092)
Distance: 732m

In this situation, the two mobile nodes can send/receive packets to each
other. However if I set them at the same distance (732m apart) using the
same coordinate points without mobility, then they can't send/receive
packets. This problem doesn't occur in the previous Mac-802.11 and
WirelessPhy modules.

The only way I can think this could happen is when the two mobile nodes
travel close to the speed of light. Then I have to take into consideration
of special relativity. Clearly they are traveling at walking speed.

set val(chan)       Channel/WirelessChannel
set val(prop)       Propagation/TwoRayGround
set val(netif)      Phy/WirelessPhyExt
set val(mac)        Mac/802_11Ext
set val(netif)    Phy/WirelessPhyExt
set val(mac)    Mac/802_11Ext
set val(ifq)        Queue/DropTail/PriQueue
set val(ll)         LL
set val(ant)        Antenna/OmniAntenna
set val(x)          1500
set val(y)          1000
set val(ifqlen)     20
set val(nn)         2
set val(rtg)        DumbAgent
set val(stop)       10000


Thanks,
Tommy Nguyen