NS-2仿真中移动节点的设置

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要做一个4个节点的Ad hoc网络仿真,实验环境和要求是:
采 用的无线网拓扑结构,主机节点数共有4个;节点1到4的初始位置坐标分别为(0,1 000)、(0,800)、(0,600)和(400,600),节点1和2在仿真中保持静止不动,节点3和4则以60m/s速度分别向坐标(0,0)和 (400,0)位置方向垂直移动。系统带宽为2Mbps,系统节点缺省无线传输半径约为500m。仿真使用的业务流量为FTP,每包发送512字节,发送 速度10包/s。采用静态路由方式,节点1在1.5s发包给节点2,节点3在3.5s发包给节点4。仿真时间一共10s,选取节点2处的估计可用带宽进行 分析。
下面是基本环境仿真的adhoc.tcl源码:

# This script is created by emile.Y.S Xiang
#===================================
#              定义模拟变量                           
#===================================
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(x)      1000                               ;# X dimension of topology
set val(y)      1000                               ;# Y dimension of topology
set val(cp)     ""                                 ;# node movement model file
set val(sc)     ""                                 ;# traffic model file
set val(ifqlen) 50                                 ;# max packet in ifq
set val(nn)     4                                  ;# number of mobilenodes
set val(seed)   0.0
set val(stop)   10.0                               ;# time of simulation end
set val(tr)     adhoc.tr                           ;# trace file name
set val(rp)     DSDV                               ;# routing protocol
set AgentTrace ON
set RouterTrace ON
set MacTrace    OFF
#===================================
#              建立相关档案         
#===================================
# Initialize Global Variables
set ns_    [new Simulator]                          ;#产生ns simulator实例
$ns_ color 1 Blue
$ns_ color 2 Red

# 设定trace file
$ns_ use-newtrace                                   ;#使用新的trace format
set namfd [open adhoc.nam w]                        ;#产生nam trace file
$ns_ namtrace-all-wireless $namfd $val(x) $val(y)   ;#模拟时产生需要的结果文件
set tracefd [open $val(tr) w]                       ;#产生trace file
$ns_ trace-all $tracefd                             ;#模拟时产生需要的结果文件

#建立topology对象,以记录mobilenodes在拓扑內移动的情况
set topo [new Topography]
# 拓扑的范围为 1000m x 1000m
$topo load_flatgrid $val(x) $val(y)

# 建立channel
set chan [new $val(chan)]

# 创建god
set god_ [create-god $val(nn)]
#===================================
#              无线节点配置         
#===================================
# Create the specified number of mobile nodes [$val(nn)] and "attach" them to
# the channel. Four nodes are created : node(0), node(1), node(2) and node(3)
# 设定Mobile Node的参数
$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) \
                 -channel $chan \
                 -topoInstance $topo \
                 -agentTrace ON \
                 -routerTrace OFF \
                 -macTrace OFF \
                 -movementTrace OFF
#===================================
#              新建Node              
#===================================
for {set i 0} {$i < $val(nn) } {incr i} {
set node_($i) [$ns_ node]
$node_($i) random-motion 0 ;# 使各节点非随机移动
}

# Provide initial (X,Y, for now Z=0) co-ordinates for mobilenodes
# 建立第0个Node,开始时,位置在(0.0, 1000.0)
$node_(0) set X_ 0.0
$node_(0) set Y_ 1000.0
$node_(0) set Z_ 0.0
# 建立第1个Node,开始时,位置在(0.0, 800.0)
$node_(1) set X_ 0.0
$node_(1) set Y_ 800.0
$node_(1) set Z_ 0.0
# 建立第2个Node,开始时,位置在(0.0, 600.0)
$node_(2) set X_ 0.0
$node_(2) set Y_ 600.0
$node_(2) set Z_ 0.0
# 建立第3个Node,开始时,位置在(400.0, 600.0)
$node_(3) set X_ 400.0
$node_(3) set Y_ 600.0
$node_(3) set Z_ 0.0

# Load the god object with shortest hop information
# 在节点0和节点1之间最短的hop数为1
$god_ set-dist 0 1 1
# 在节点1和节点2之间最短的hop数为1
$god_ set-dist 1 2 1
# 在节点0和节点2之间最短的hop数为2
$god_ set-dist 0 2 2
# 在节点2和节点3之间最短的hop数为1
$god_ set-dist 2 3 1
# 在节点0和节点3之间最短的hop数为1
$god_ set-dist 0 3 1
# 在节点1和节点3之间最短的hop数为1
$god_ set-dist 1 3 1
#===================================
#              产生Movement         
#===================================
# Now produce some simple node movements
# Node_(2) and Node_(3) starts to move downward
set god_ [God instance]
# 从0秒开始,节点2开始从位置(0,600)移動到(0,0),速度為60.0 m/s
$ns_ at 0.0 "$node_(2) setdest 0.0 0.0 60.0"
# 从0秒开始,节点3开始从位置(400,600)移動到(400,0),速度為60.0 m/s
$ns_ at 0.0 "$node_(3) setdest 400.0 0.0 60.0"
#===================================
#       建立FTP业务,基于TCP来承载 
#===================================
# 在节点0和节点1间设定第0个连线(FTP-TCP),且在时间为1.5秒开始发送
set tcp0 [new Agent/TCP/Newreno]
$tcp0 set fid_ 1
set sink0 [new Agent/TCPSink]
$ns_ attach-agent $node_(0) $tcp0
$ns_ attach-agent $node_(1) $sink0
$ns_ connect $tcp0 $sink0
set ftp0 [new Application/FTP]
$ftp0 attach-agent $tcp0
$ns_ at 1.5 "$ftp0 start"
$ns_ at 10.0 "$ftp0 stop"

# 在节点2和节点3间设定第1个连线(FTP-TCP),且在时间为3.5秒开始发送
set tcp1 [new Agent/TCP/Newreno]
$tcp1 set fid_ 2
set sink1 [new Agent/TCPSink]
$ns_ attach-agent $node_(2) $tcp1
$ns_ attach-agent $node_(3) $sink1
$ns_ connect $tcp1 $sink1
set ftp1 [new Application/FTP]
$ftp1 attach-agent $tcp1
$ns_ at 3.5 "$ftp1 start"
$ns_ at 10.0 "$ftp1 stop"

# 在nam中定义节点初始所在位置
for {set i 0} {$i < $val(nn)} {incr i} {
# The function must be called after mobility model is defined.
$ns_ initial_node_pos $node_($i) 60
}

# 告诉MobileNode模拟已结束
for {set i 0} {$i < $val(nn) } {incr i} {
$ns_ at $val(stop) "$node_($i) reset";
}
#===================================
#              结束模拟             
#===================================
# 结束nam与模拟器
$ns_ at $val(stop) "$ns_ nam-end-wireless $val(stop)"
$ns_ at $val(stop) "stop"
$ns_ at $val(stop) "puts \"NS EXITING...\" ; $ns_ halt"

# 设定模拟器用的stop function
proc stop {} {
global ns_ tracefd namfd
$ns_ flush-trace
close $tracefd
close $namfd
exec nam adhoc.nam &
exit 0
}

puts $tracefd "M 0.0 nn $val(nn) x $val(x) y $val(y) rp $val(rp)"
puts $tracefd "M 0.0 sc $val(sc) cp $val(cp) seed $val(seed)"
puts $tracefd "M 0.0 prop $val(prop) ant $val(ant)"
puts "Starting Simulation..."
$ns_ run

运行ns adhoc.tcl命令后,报错信息如下:
ns: _o46 setdest 0.0 600.0 60.0: 
    (_o46 cmd line 1)
    invoked from within
"_o46 cmd setdest 0.0 600.0 60.0"
    invoked from within
"catch "$self cmd $args" ret"
    invoked from within
"if [catch "$self cmd $args" ret] {
set cls [$self info class]
global errorInfo
set savedInfo $errorInfo
error "error when calling class $cls: $args" $..."
    (procedure "_o46" line 2)
    (SplitObject unknown line 2)
    invoked from within
"_o46 setdest 0.0 600.0 60.0"
可以看出问题出在使得两个移动节点移动的代码处(tcl源码中红色部分标记),把移动节点移动的两行代码去掉,ns-2仿真就不报错了,一加上就报错。
我的4个节点是2个固定,2个移动。

反复调试不得其解,于是仔细检查了一下源代码
在MobileNode::command(int argc, const char*const* argv)的处理setdest命令的接口中,有一句判断

CODE:if (set_destination(atof(argv[2]), atof(argv[3]), atof(argv[4])) < 0)
    return TCL_ERROR;
再去看这个函数:MobileNode::set_destination(double x, double y, double s),会发现里面有这一段:

CODE:if(x >= T_->upperX() || x <= T_->lowerX())
return -1;
if(y >= T_->upperY() || y <= T_->lowerY())
return -1;
也就是说,你不能让你的Node移动到边界,所以,当把脚本改成:
# 从0秒开始,节点2开始从位置(0,600)移動到(0,0),速度為60.0 m/s
$ns_ at 0.0 "$node_(2) setdest 0.1 0.1 60.0 "
# 从0秒开始,节点3开始从位置(400,600)移動到(400,0),速度為60.0 m/s
$ns_ at 0.0 "$node_(3) setdest 400.0 0.1 60.0 "

就好了


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