---------- Forwarded message ----------
Date: 2008/10/29
Subject: simulation problems on 802.11 infrastructure mode
To: ns-users@isi.edu

Dear all,
I'm doing some simulations on 802.11 infrastructure mode in ns2 using
"Phy/WirelessPhy & Mac/802_11" implementations within ns2.

  When I did a simple simulation which involved 24 clients and 5 APs(all
clients are evenly distributed in a 300*300 area and 5 APs are located at
the four
corners and the center ),  everything went well if the CBR data rate is low
enough(eg. 256kB). While if the CBR data rate is higher (1MB), there rose a
segmentation faults and it cannot be tracked in GDB easily ( the fault is
listed below).  Because I didn't change any code in NS 2, there may be some
bugs in the 802.11 Mac implementation. Could any one give me any advice,
pls?  I really appreciate it.

Best regards,

Wang Hui

Below is the tcl script and gdb debug information.

set val(chan)           Channel/WirelessChannel    ;#Channel Type
set val(prop)           Propagation/TwoRayGround   ;# radio-propagation
set val(netif)          Phy/WirelessPhy            ;# network interface type
set val(mac)            Mac/802_11                 ;# MAC type
set val(ifq)            Queue/DropTail           ;# interface queue type
set val(ll)             LL                         ;# link layer type
set val(ant)            Antenna/OmniAntenna        ;# antenna model
set val(ifqlen)         50                        ;# max packet in ifq
set val(nn)             29                         ;# number of mobilenodes
set val(rp)             DumbAgent                  ;# routing protocol
set val(x)        300
set val(y)        300

Mac/802_11 set dataRate_ 11Mb

#Phy/WirelessPhy set CSThresh_ 10.00e-12
#Phy/WirelessPhy set RXThresh_ 10.00e-11
#Phy/WirelessPhy set Pt_ 0.1
#Phy/WirelessPhy set Pt_ 7.214e-3

# Initialize Global Variables
set ns_        [new Simulator]
set tracefd     [open asso.tr w]
$ns_ trace-all $tracefd

# set up topography object
set topo       [new Topography]

$topo load_flatgrid $val(x) $val(y)

# Create God
create-god $val(nn)

# Create channel
set chan_1_ [new $val(chan)]

$ns_ node-config -adhocRouting $val(rp) \
        -llType $val(ll) \
        -macType $val(mac) \
        -ifqType $val(ifq) \
        -ifqLen $val(ifqlen) \
        -antType $val(ant) \
        -propType $val(prop) \
        -phyType $val(netif) \
        -topoInstance $topo \
        -agentTrace ON \
        -routerTrace OFF \
        -macTrace OFF \
        -movementTrace OFF \
        -channel $chan_1_

      for {set i 0} {$i < [expr $val(nn)]} {incr i} {
                set node_($i) [$ns_ node]

                $node_($i) random-motion 0              ;# disable random
          set mac_($i) [$node_($i) getMac 0]

              #$mac_($i) set RTSThreshold_ 3000

        #$node_($i) set X_ $i
          #$node_($i) set Y_ 0       ;# Horizontal arrangement of nodes
          #$node_($i) set Z_ 0.0


source  ./asso.scn
#Set Node 0 and Node $val(nn) as the APs. Thus the APs are the ends of the
horizontal line. Each STA receives different power levels.

set AP_ADDR1 [$mac_(25) id]
$mac_(25) ap $AP_ADDR1

set AP_ADDR2 [$mac_(26) id]
$mac_(26) ap $AP_ADDR2

set AP_ADDR3 [$mac_(12) id]
$mac_(12) ap $AP_ADDR3

set AP_ADDR4 [$mac_(27) id]
$mac_(27) ap $AP_ADDR4

set AP_ADDR5 [$mac_([expr $val(nn) - 1]) id]
$mac_([expr $val(nn) - 1]) ap $AP_ADDR5

#$mac_([expr $val(nn) - 1]) set BeaconInterval_ 0.2

#$mac_(1) ScanType ACTIVE

#for {set i 3} {$i < [expr $val(nn) - 1]} {incr i} {
#    $mac_($i) ScanType PASSIVE    ;#Passive

for {set i 0} {$i < 12} {incr i} {
    $mac_($i) ScanType PASSIVE

for {set i 13} {$i < 25} {incr i} {
    $ns_ at 3.0 "$mac_($i) ScanType PASSIVE"

#$ns_ at 3.0 "$mac_(2) ScanType ACTIVE"

Application/Traffic/CBR set packetSize_ 2000
Application/Traffic/CBR set rate_ 0.5mB
#Application/Traffic/CBR set interval_  25n

for {set i 0} {$i < 25} {incr i} {
  if {$i != 12} {
    set udp1($i) [new Agent/UDP]

    $ns_ attach-agent $node_($i) $udp1($i)
    set cbr1($i) [new Application/Traffic/CBR]
    $cbr1($i) attach-agent $udp1($i)

set base0 [new Agent/Null]
$ns_ attach-agent $node_(11) $base0

set base1 [new Agent/Null]
$ns_ attach-agent $node_(8) $base1

set base2 [new Agent/Null]
$ns_ attach-agent $node_(18) $base2

$ns_ connect $udp1(6) $base0
$ns_ connect $udp1(7) $base1

$ns_ connect $udp1(13) $base2

$ns_ at 2.0 "$cbr1(6) start"

$ns_ at 4.0 "$cbr1(7) start"

$ns_ at 6.0 "$cbr1(13) start"

#$ns_ at 10.0 "$node_(4) setdest 300.0 1.0 30.0"

$ns_ at 200.0 "stop"
$ns_ at 200.0 "puts \"NS EXITING...\" ; $ns_ halt"

proc stop {} {
    global ns_ tracefd
    $ns_ flush-trace
    close $tracefd
    exit 0

puts "Starting Simulation..."
$ns_ run


num_nodes is set 29


Starting Simulation...

channel.cc:sendUp - Calc highestAntennaZ_ and distCST_

highestAntennaZ_ = 1.5,  distCST_ = 550.0


Program received signal SIGSEGV, Segmentation fault.

0x088c4f73 in ?? ()

(gdb) bt

#0  0x088c4f73 in ?? ()

#1  0x081a7626 in Scheduler::run (this=0x879ea48) at common/scheduler.cc:129

#2  0x081a78e5 in Scheduler::command (this=0x879ea48, argc=2,

    at common/scheduler.cc:198

#3  0x083cb07a in TclClass::dispatch_cmd ()

#4  0x083cfdec in OTclDispatch (cd=<value optimized out>, in=0x85d96c0,

    argc=3, argv=0xbf9de19c) at otcl.c:434

#5  0x083d6bbe in TclInvokeStringCommand ()

#6  0x083d8716 in TclEvalObjvInternal ()

#7  0x08402e51 in TclExecuteByteCode ()

#8  0x0840768c in TclCompEvalObj ()

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