MAC冲突窗口-无线网络102

From liuchng_xt：NS lab的网站地址 http://www.crhc.illinois.edu/wireless/assignments/simulations/

转载自：http://blog.chinaunix.net/uid-232277-id-2485895.html

介绍

本实验目标是调查冲突窗口大小对IEEE802.11性能的影响。

该标准要求所有节点都选择一个从0到CW的随机的回退时间。

最初，CW被设置为CWMin，但是随着冲突的发生，窗口大小会变成2倍，直到达到CWMax的值。

参数

区域：150m X 150m

节点数：ns cwsim.tcl -rlen 2  #节点数= rlen^2，本例rlen为2.

CW值：初始脚本中CWMin=CWmax=CW=31 

      可以通过$val(mac) set CWMin_ 31

         $val(mac) set CWMax_ 31

 进行设置

Flow：CBR

包大小：512 bytes

结果统计

Packet Delivery Ratio (PDR)=[Packets Received] / [Packets Sent]

    通过得知发送或者接收包的数量进行统计。本例用下面的脚本统计发送包数。

    grep AGT cwsim.tr |grep ^s |grep cbr|wc -l

接收包数用如下脚步统计。

grep AGT cwsim.tr |grep ^r |grep cbr|wc -l

接收的包数应该等于或者少于发送数。

Throughput=512 x 8 x [Packets Received] / 25  bits/second 、

本例代码如下

# Copyright (c) 1997 Regents of the University of California.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# 3. All advertising materials mentioning features or use of this software
# must display the following acknowledgement:
# This product includes software developed by the Computer Systems
# Engineering Group at Lawrence Berkeley Laboratory.
# 4. Neither the name of the University nor of the Laboratory may be used
# to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#


# Script to Study Impact of CW size 
#V.B., 2005 

# ======================================================================
# Define options
# ======================================================================
set val(chan) Channel/WirelessChannel ;# channel type
set val(prop) Propagation/TwoRayGround ;# radio-propagation model
set val(netif) Phy/WirelessPhy ;# network interface type
set val(mac) Mac/802_11 ;# MAC type
set val(ifq) Queue/DropTail/PriQueue ;# 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) 25 ;# default number of mobilenodes
set val(rp) AODV ;# routing protocol
set val(sc)        "./scenario"         ;# scenario file
set val(x)        150.0             ;
set val(y)        150.0             ;
set val(simtime)    25.0             ; #sim time
set val(rlen)        5             ;
# ======================================================================
# Main Program
# ======================================================================



if { $argc != 2 } {
        puts "Wrong no. of cmdline args."
    puts "Usage: ns cwsim.tcl -rlen <rlen>"
        exit 0
}


proc getopt {argc argv} {
        global val
        lappend optlist rlen
 
        for {set i 0} {$i < $argc} {incr i} {
                set arg [lindex $argv $i]
                if {[string range $arg 0 0] != "-"} continue
                set name [string range $arg 1 end]
                set val($name) [lindex $argv [expr $i+1]]
        }

    set val(nn) [expr $val(rlen) * $val(rlen)]    
         
}


 

getopt $argc $argv
#
# Initialize Global Variables
#
set ns_        [new Simulator]
set tracefd [open cwsim.tr w]
$ns_ trace-all $tracefd

set namtrace [open cwsim.nam w] ;# for nam tracing
$ns_ namtrace-all-wireless $namtrace $val(x) $val(y)
$ns_ use-newtrace

# set up topography object
set topo [new Topography]

$topo load_flatgrid $val(x) $val(y)

#
# Create God
#

set god_ [ create-god $val(nn) ]



$val(mac) set bandwidth_ 22.0e6 
$val(mac) set CWMin_ 31
$val(mac) set CWMax_ 31

#
# Create the specified number of mobilenodes [$val(nn)] and "attach" them
# to the channel. 

# configure node


        $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) \
             -channelType $val(chan) \
             -topoInstance $topo \
             -agentTrace ON \
             -routerTrace OFF \
             -macTrace ON \
             -movementTrace OFF \
             -numif 1 # multi-if support added fromhttps://docs.google.com/uc?id=0B2X9227uwfVKN2VkZDQ0YWItZDY2Yy00ZGMwLWFlZWItYTY5NDgwNzVjNzY1&export=download&hl=en


    for {set i 0} {$i < $val(nn) } {incr i} {
        set node_($i) [$ns_ node]    
        $node_($i) random-motion 0        ;# disable random motion
    }




#
# Provide initial (X,Y, Z=0) co-ordinates for mobilenodes
#


    set gridspace [expr 150.0 / $val(rlen)]
    

    for {set i 0} {$i < $val(rlen) } {incr i} {
        for {set j 0} {$j < $val(rlen) } {incr j} {
            set a [expr $j + [expr $i * $val(rlen)]]
            $node_($a) set X_ [expr 0.0 + [ expr $i * $gridspace]]
            $node_($a) set Y_ [expr 0.0 + [ expr $j * $gridspace]]
            $node_($i) set Z_ 0.0
        }
    }



# Define node initial position in nam

for {set i 0} {$i < $val(nn)} {incr i} {

    # 20 defines the node size in nam, must adjust it according to your scenario
    # The function must be called after mobility model is defined
    
    $ns_ initial_node_pos $node_($i) 20



        set udp_($i) [new Agent/UDP]
        $ns_ attach-agent $node_($i) $udp_($i)
                
        set cbr_($i) [new Application/Traffic/CBR]
        $cbr_($i) set packetSize_ 512
        $udp_($i) set packetSize_ 512 
        $cbr_($i) set interval_ 0.01 
        $cbr_($i) set random_ 0.348 
        $cbr_($i) set maxpkts_ 1000000
        $cbr_($i) attach-agent $udp_($i)

        set null_($i) [new Agent/Null]
        $ns_ attach-agent $node_($i) $null_($i)


}

    
#
# Tell nodes when the simulation ends
#
for {set i 0} {$i < $val(nn) } {incr i} {
        
        
    set dst [expr [expr $i + $val(rlen)] % $val(nn)] 
    $ns_ connect $udp_($i) $null_($dst)
    $ns_ at [expr 0.01 * $i] "$cbr_($i) start"
    $ns_ at $val(simtime) "$node_($i) reset";
}
$ns_ at $val(simtime) "stop"
$ns_ at $val(simtime).01 "puts \"NS EXITING...\" ; $ns_ halt"
proc stop {} {
    global ns_ tracefd
    $ns_ flush-trace
    close $tracefd
}

puts "Starting Simulation..."
$ns_ run