DD協(xié)議代碼分析

1、# =# Define options# =set opt(chan)Channel/WirelessChannel /物理信道類型是無線信道set opt(prop)Propagation/TwoRayGround/無線傳輸模型是woRayGroundset opt(netif)Phy/WirelessPh/網(wǎng)絡(luò)借口類型是無線物理層 set opt(mac)Mac/802_11/MAC層協(xié)議采用802.11協(xié)議set opt(ifq)Queue/DropTail/PriQueue/接口隊(duì)列類型是IFQ列隊(duì)set opt(ll)LL/邏輯鏈路層類型LL層set opt(ant) Antenna

2、/OmniAntenna/無線模型是全向天線set opt(filters) GradientFilter ;# old name for twophasepull filter/ twophasepull過濾器set opt(x)670 ;# X dimension of the topography設(shè)定拓?fù)浞秶L度，670Mset opt(y)670 ;# Y dimension of the topographyset opt(ifqlen)50 ;# max packet in ifq/網(wǎng)絡(luò)接口隊(duì)列的大小50set opt(nn)10 ;# number of nodes/節(jié)點(diǎn)數(shù)set

3、 opt(sndr) 1 ;# no of senders/沒有發(fā)送方set opt(rcvr) 4 ;# no of recvrs/沒有recvrsset opt(seed)0.0/設(shè)置隨機(jī)數(shù)種子set opt(stop)100 ;# simulation time/仿真時(shí)間set opt(tr)"DD.tr" ;# trace file/跟蹤文件set opt(nam) "DD.nam" ;# nam file/文件名set opt(adhocRouting) Directed_Diffusion/路由協(xié)議 # =LL set mindelay_50

4、us/設(shè)置mindelay時(shí)間LL set delay_25us/設(shè)置延遲時(shí)間LL set bandwidth_0 ;# not used/沒有使用的帶寬為0Queue/DropTail/PriQueue set Prefer_Routing_Protocols 1# unity gain, omni-directional antennas/單位增益，全向天線# set up the antennas to be centered in the node and 1.5 meters above it/天線設(shè)立在節(jié)點(diǎn)中心1.5米以上Antenna/OmniAntenna set X_ 0An

5、tenna/OmniAntenna set Y_ 0Antenna/OmniAntenna set Z_ 1.5Antenna/OmniAntenna set Gt_ 1.0Antenna/OmniAntenna set Gr_ 1.0# Initialize the SharedMedia interface with parameters to make/界面參數(shù)初始化# it work like the 914MHz Lucent WaveLAN DSSS radio interface/工作如在914MHz擴(kuò)頻朗訊WaveLAN無線接口Phy/WirelessPhy set CPThr

6、esh_ 10.0Phy/WirelessPhy set CSThresh_ 1.559e-11Phy/WirelessPhy set RXThresh_ 3.652e-10Phy/WirelessPhy set Rb_ 2*1e6Phy/WirelessPhy set Pt_ 0.2818/傳輸功率Phy/WirelessPhy set freq_ 914e+6 Phy/WirelessPhy set L_ 1.0其中，RXThresh_指的是receiving threshold (RTX)，它是由節(jié)點(diǎn)傳輸范圍250m計(jì)算出來的，CSThresh_指的是carrier-sense

7、 threshold (CTX)，它是由載波偵聽范圍550m計(jì)算出來的。CSThresh_與RXThresh_這兩個(gè)值是功率的threshold值。通過在tcl腳本中設(shè)置它們的大小，就可以相應(yīng)設(shè)置節(jié)點(diǎn)傳輸范圍和載波偵聽范圍。=# Main Program/主程序# =# Initialize Global Variables/初始化全局變量#set ns_new Simulator 建立一個(gè)模擬實(shí)例建立一個(gè)拓?fù)鋱D對(duì)象，記錄節(jié)點(diǎn)的移動(dòng)情況set toponew Topographyset tracefdopen $opt(tr) w#$ns_ use-newtrace$ns_ trac

8、e-all $tracefdset nf open $opt(nam) w$ns_ namtrace-all-wireless $nf $opt(x) $opt(y)#$ns_ use-newtrace$topo load_flatgrid $opt(x) $opt(y)set god_ create-god $opt(nn)#global node setting/全局節(jié)點(diǎn)設(shè)置傳感器節(jié)點(diǎn)屬性的配置參數(shù)的部分程序代碼如下所示：$ns_ node-config -adhocRouting $opt(adhocRouting) -llType $opt(ll) -macType $opt(mac)

9、 -ifqType $opt(ifq) -ifqLen $opt(ifqlen) -antType $opt(ant) -propType $opt(prop) -phyType $opt(netif) -channelType $opt(chan) -topoInstance $topo -diffusionFilter $opt(filters) -agentTrace ON -routerTrace ON -macTrace ON #在本文所有的模擬實(shí)驗(yàn)中，MAC層使用的是16Mbs速率的80211協(xié)議，也就是說MAC層實(shí)現(xiàn)了IEEE 80211 MAC協(xié)議。在本文模擬中所使用的MAC協(xié)

10、議不是一個(gè)最滿意的選擇，基于對(duì)無線傳感器網(wǎng)絡(luò)能量方面的考慮，在MAC層最好選擇時(shí)分復(fù)用(TimeDivision Multiple Access，簡稱TDIlA)方式，而不是使用RTscTS通道請求的方式。簡面言之，這些原因與節(jié)點(diǎn)空閑時(shí)無線通信所消耗的能量有關(guān)，對(duì)于TDMA方式的MAC協(xié)議，節(jié)點(diǎn)空閑期問無線電設(shè)各處于休眠狀態(tài)，但是IEEE 802II MAC協(xié)議在節(jié)點(diǎn)空閑期間和在傳送數(shù)據(jù)包期間所消耗的能量卻都是一樣多的。為了使模擬實(shí)驗(yàn)和實(shí)際的無線傳感器網(wǎng)絡(luò)的能量消耗更加接近隨刪。設(shè)置節(jié)點(diǎn)空閑期間所消耗的能量大約是接收數(shù)據(jù)包所消耗能量的10，即大約是發(fā)送數(shù)據(jù)包所消耗能量的5# Create th

11、e specified number of nodes $opt(nn) and "attach" them# to the channel. 創(chuàng)建指定編號(hào)的節(jié)點(diǎn)并連接到信道for set i 0 $i < $opt(nn) incr i set node_($i) $ns_ node $i $node_($i) color black $node_($i) random-motion 0;# disable random motion $god_ new_node $node_($i)puts "Loading connection pattern.&qu

12、ot;/ 加載連接模式設(shè)定節(jié)點(diǎn)初始位置$node_(0) set X_ 18$node_(0) set Y_ 331$node_(0) set Z_ 0$node_(1) set X_ 11$node_(1) set Y_ 36$node_(1) set Z_ 0$node_(2) set X_ 224$node_(2) set Y_ 20$node_(2) set Z_ 0$node_(3) set X_ 158$node_(3) set Y_ 139$node_(3) set Z_ 0$node_(4) set X_ 101$node_(4) set Y_ 147$node_(4) set

13、 Z_ 0$node_(5) set X_ 321$node_(5) set Y_ 382$node_(5) set Z_ 0$node_(6) set X_ 149$node_(6) set Y_ 314$node_(6) set Z_ 0$node_(7) set X_ 381$node_(7) set Y_ 78$node_(7) set Z_ 0$node_(8) set X_ 113$node_(8) set Y_ 400$node_(8) set Z_ 0$node_(9) set X_ 258$node_(9) set Y_ 113$node_(9) set Z_ 0# 1 pi

14、ng sender/ping 發(fā)送方for set i 0 $i < $opt(sndr) incr i set src_($i) new Application/DiffApp/PingSender/TPP $ns_ attach-diffapp $node_(expr $i + 2) $src_($i) $ns_ at expr 0.12 * expr 1+$i "$src_($i) publish"# 4 ping receivers/ping 接收方for set i 0 $i < $opt(rcvr) incr i set snk_($i) new A

15、pplication/DiffApp/PingReceiver/TPP $ns_ attach-diffapp $node_(expr $opt(nn)-1 -$i) $snk_($i) $ns_ at expr 1.15*expr 1+$i "$snk_($i) subscribe"#Define node initial position in nam/定義節(jié)點(diǎn)初始位置在namfor set i 0 $i < $opt(nn) incr i $ns_ initial_node_pos $node_($i) 20# Tell nodes when the simulation ends/仿真結(jié)束的時(shí)候告訴節(jié)點(diǎn)#for set i 0 $i < $opt(nn) incr i $ns_ at $opt(stop).1 "$node_($i) reset"proc finish global ns_ tracefd nf$ns_ flush-traceclose $tracefdclose $nfexec nam DD.nam &exit 0# tell nam the si