WSN中LEACH協(xié)議源碼分析

WSN中LEACH協(xié)議源碼分析分析（一）首先對wireless.tcl進(jìn)行分析，先對默認(rèn)的腳本選項(xiàng)進(jìn)行初始化：set opt(chan)Channel/WirelessChannelset opt(prop) Propagation/TwoRayGroundset opt(netif)Phy/WirelessPhyset opt(mac) Mac/802_11set opt(ifq) Queue/DropTail/PriQueueset opt(ll) LLset opt(ant) Antenna/OmniAntennaset opt(x) 0 ;# X dimension of the topographyset opt(y) 0 ;# Y dimension of the topographyset opt(cp) ""set opt(sc) "./mobility/scene/scen-670x670-50-600-20-2" ;# scenario fileset opt(ifqlen)50;# max packet in ifset opt(nn) 51 ;# number of nodesset opt(seed) 0.0set opt(stop) 10.0 ;# simulation timeset opt(tr) out.tr ;# trace fileset opt(rp) dsdv ;# routing protocol scriptset opt(lm) "on" ;# log movement在這個(gè)wireless.tcl中設(shè)置了一些全局變量：# Initialize Global Variables#set ns_ new Simulatorset chan new $opt(chan)set prop new $opt(prop)set topo new Topographyset tracefd open $opt(tr) w$topo load_flatgrid $opt(x) $opt(y)$prop topography $topo這些初始化將在后面的使用中用到，該文件最重要的是創(chuàng)建leach節(jié)點(diǎn)：創(chuàng)建方法如下： elseif string compare $opt(rp) "leach" = 0 for set i 0 $i < $opt(nn) incr i leach-create-mobile-node $i如果路由協(xié)議是leach協(xié)議，則在Uamps.tcl中調(diào)用leach-create-mobile-node方法創(chuàng)建leach節(jié)點(diǎn)。將在第二小節(jié)講如何創(chuàng)建leach節(jié)點(diǎn)。for set i 0 $i < $opt(nn) incr i $ns_ at $opt(stop). "$node_($i) reset" /完成后，重置節(jié)點(diǎn)的應(yīng)用$ns_ at $opt(stop).00000001 "puts "NS EXITING." ; $ns_ halt"if $opt(sc) = "" puts "* NOTE: no scenario file specified." set opt(sc) "none" else puts "Loading scenario file."source $opt(sc)puts "Load complete."ns在什么時(shí)候結(jié)束simulation，并告訴ns加載sc場景文件。最后$ns_ run則ns就開始運(yùn)行了。分析（二）上節(jié)對wireless.tcl進(jìn)行了簡要的分析，接下來對Uamps.tcl腳本進(jìn)行分析。set opt(Efriss_amp) expr expr 1.1 * $opt(RXThresh) * 16 * $PI * $PI / expr $opt(bw) * $opt(Gt) * $opt(Gr) * $l * $l# Etwo_ray_amp = RXThresh / (Rb Gt Gr ht2 hr2)set opt(Etwo_ray_amp) expr 1.1 * $opt(RXThresh) / expr $opt(bw) * $opt(Gt) * $opt(Gr) * $opt(ht) * $opt(ht) * $opt(ht) * $opt(ht)set opt(EXcvr) 50e-9 ;# Energy for radio circuitryset opt(e_bf) 5e-9 ;# Beamforming energy (J/bit)set opt(Esense) 0 ;# Sensing energy (J/bit)set opt(thresh_energy) 0.00 ;# Threshold for power adaptationset opt(Pidle) 0 ;# Idle power (W)set opt(Psleep) 0 ;# Sleep power (W)set initialized 0set rng_ new RNG#用于產(chǎn)生隨機(jī)數(shù) 首先往opt數(shù)組里面添加一些變量，并對這些變量進(jìn)行初化。opt(Psleep) ，opt(Pidle)， opt(thresh_energy)在ns-leach.tcl中使用到，這個(gè)是計(jì)算單位時(shí)間空閑所消耗的能量和休眠所消耗的能量。這個(gè)腳本主要是創(chuàng)建leach節(jié)點(diǎn)：if $initialized = 0 #remove old trace sens_init set initialized 1 # Remove old trace files. catch "eval exec rm glob -nocomplain $opt(dirname)/TDMAschedule.*.txt" catch "exec rm $opt(dirname)/$opt(filename).energy" catch "exec rm $opt(dirname)/$opt(filename).data" catch "exec rm $opt(dirname)/$opt(filename).alive" catch "exec rm $opt(dirname)/startup.energy" catch "exec rm $opt(dirname)/init.energy"如果沒有初始化過，則將以前的跟蹤文件刪除，接著回到創(chuàng)建leach的函數(shù)中，創(chuàng)建節(jié)點(diǎn)：if $id != $opt(nn_) puts -nonewline "$id " #important set node_($id) new MobileNode/ResourceAwareNode else puts "($opt(nn_) = BS)" set node_($id) new MobileNode/ResourceAwareNode $BS_NODE 如果不是簇頭節(jié)點(diǎn)則將$opt(nn_)-1個(gè)節(jié)點(diǎn)設(shè)置為一般節(jié)點(diǎn)，將$opt(nn_)設(shè)置為BS節(jié)點(diǎn)。newMobileNode/ResourceAwareNode函數(shù)是在ns-ranode.tcl中。分析完這個(gè)我們接下來分析newMobileNode/ResourceAwareNode這個(gè)函數(shù)。set node $node_($id) if $id != $opt(nn_) # Set initial node energy. if $opt(eq_energy) = 1 $node set-energy $opt(init_energy) $opt(thresh_energy) else 由于eq-energy在leach-test中給定，將eq-energy=1；則每個(gè)節(jié)點(diǎn)都會對能量進(jìn)行初始化，設(shè)置節(jié)點(diǎn)的初始能量和門檻能量（個(gè)人理解，死亡能量）。set high_e_nodes list 97 19 12 87 8 22 83 55 34 72 if lsearch $high_e_nodes $id = -1 set E 2 else set E 200 $node set-energy $E $opt(thresh_energy) set initf open "$opt(dirname)/init.energy" a puts $initf "$idt$E" close $initf將不屬于list中的能量初始化能量設(shè)置為2，將屬于list中的能量設(shè)置為200.并將初始化能量寫到init.energy中，將節(jié)點(diǎn)id和節(jié)點(diǎn)初始能量寫進(jìn)去。 else # Base station has an infinite amount of energy. $node set-energy 50000 $opt(thresh_energy) 節(jié)點(diǎn)為簇頭節(jié)點(diǎn)，則將節(jié)點(diǎn)的初始化能量設(shè)置為50000，能量無限。到此為止，創(chuàng)建節(jié)點(diǎn)完成并將每個(gè)節(jié)點(diǎn)的能量初始化完成。下一節(jié)將分析ns-ranode.tcl腳本。區(qū)分普通節(jié)點(diǎn)和簇頭節(jié)點(diǎn)的不同。接下來是配置節(jié)點(diǎn)信道和跟蹤文件：$ns_ at 0.0 "$node_($id) start-app" ns在0的時(shí)候啟動應(yīng)用，應(yīng)用在ns-ranode.tcl中分析。分析（三）對前面兩個(gè)腳本進(jìn)行分析后，已經(jīng)創(chuàng)建好節(jié)點(diǎn)和設(shè)置好節(jié)點(diǎn)的初始能量，將opt(nn_)-1個(gè)節(jié)點(diǎn)設(shè)置為普通節(jié)點(diǎn)，而將opt(nn_)設(shè)置為bs?，F(xiàn)在對ns-ranode.tcl進(jìn)行分析。好了我們現(xiàn)在就開始分析這個(gè)腳本。Class MobileNode/ResourceAwareNode -superclass Node/MobileNodeMobileNode/ResourceAwareNode instproc init argsset bs_node lindex $args 0 eval $self next lreplace $args 0 0 args由參數(shù)傳遞進(jìn)來，若節(jié)點(diǎn)為簇頭節(jié)點(diǎn)則bs_node=1，調(diào)用父類初始化函數(shù)。 set ResourceManager_ new ResourceManager $ResourceManager_ Register new Resource/NeighborResource set energy new Resource/Energy$ResourceManager_ Register $energyResourceManager在ns-resouce-manager.tcl中定義的。Resource/NeighborResource在ns-neighbor-resource中對能量進(jìn)行管理。 # Create a new agent and attach it to the node if $bs_node = 1 set agent new Agent/BSAgent else set agent new Agent/RCAgent set rca_agent_ $agent 普通節(jié)點(diǎn)的應(yīng)用為RCAgent，BS的應(yīng)用為BSAGgent。 并將應(yīng)用attch到node上。 下面兩段看不明白，但是這兩段不影響看程序。 set haslist find_haslist $self id if $bs_node = 1 set rca new $opt(bsapp) else set rca new $opt(rcapp) $opt(mtype) $wantslist $haslist $ns_ attach-agent $self $agent $rca attach-agent $agent set rca_app_ $rca將bs節(jié)點(diǎn)的應(yīng)用設(shè)置為bsapp，普通節(jié)點(diǎn)的應(yīng)用設(shè)置為rcaapp，并將節(jié)點(diǎn)的服務(wù)設(shè)置為不同的服務(wù)。bsapp在ns-app.tcl中。$opt(rcapp)定義在leach.tcl中，opt(mtype)定義在leach.tcl中。set opt(rcapp) "Application/LEACH" ;# Application typeset opt(ra_adv) TxTime expr $opt(hdr_size) + 4 ;# Total time (s) for CH ADVs ;# Assume max 4(nn*%) CHsset opt(ra_adv_total) expr $opt(ra_adv)*($opt(num_clusters)*4 + 1) ;# RA Time (s) for nodes' join reqsset opt(ra_join) expr 0.01 * $opt(nn_) ;# Buffer time for join req xmittalset opt(ra_delay) TxTime expr $opt(hdr_size) + 4 ;# Maximum time required to transmit ;# a schedule (n nodes in 1 cluster)set opt(xmit_sch) expr 0.005 + TxTime expr $opt(nn_)*4+$opt(hdr_size) ;# Overhead time for cluster set-upset opt(start_xmit) expr $opt(ra_adv_total) + $opt(ra_join) + $opt(xmit_sch)一般節(jié)點(diǎn)的應(yīng)用為Application/LEACH，最終sink節(jié)點(diǎn)的應(yīng)用為Application/BSApp。通過前3次的分析得出，在分析1中定義變量，在分析2中創(chuàng)建leach節(jié)點(diǎn)，在分析3中將節(jié)點(diǎn)的應(yīng)用綁定在節(jié)點(diǎn)上。下面將分析leach的主要協(xié)議ns-leach.tcl腳本。分析（四）完成前面3個(gè)腳本的分析，最后進(jìn)行ns-leach.tcl腳本的分析.首先我們看下這個(gè)腳本要使用的有哪些功能.Application/LEACH instproc init args 對leach進(jìn)行初始化，即構(gòu)造函數(shù)。下面是leach的一些方法Application/LEACH instproc start Application/LEACH instproc getRandomNumber llim ulim 得到隨機(jī)數(shù)Application/LEACH instproc node Application/LEACH instproc nodeID Application/LEACH instproc mac Application/LEACH instproc getX Application/LEACH instproc getY Application/LEACH instproc getER Application/LEACH instproc GoToSleep 節(jié)點(diǎn)進(jìn)行休眠Application/LEACH instproc WakeUp 節(jié)點(diǎn)醒來Application/LEACH instproc setCode code Application/LEACH instproc checkAlive 節(jié)點(diǎn)是否存活A(yù)pplication/LEACH instproc isClusterHead? 判斷是否是簇頭節(jié)點(diǎn)Application/LEACH instproc hasbeenClusterHead? 判斷是否成為過簇頭節(jié)點(diǎn)Application/LEACH instproc hasnotbeenClusterHead hasbeench=0不是簇頭節(jié)點(diǎn)Application/LEACH instproc setClusterHead 設(shè)置為簇頭節(jié)點(diǎn)Application/LEACH instproc unsetClusterHead 設(shè)置為非簇頭節(jié)點(diǎn)Application/LEACH instproc decideClusterHead 決定簇頭節(jié)點(diǎn)，非常重要Application/LEACH instproc advertiseClusterHead 廣播簇頭節(jié)點(diǎn)Application/LEACH instproc findBestCluster 找到最佳簇Application/LEACH instproc informClusterHead 通知簇頭節(jié)點(diǎn)Application/LEACH instproc createSchedule 創(chuàng)建TDMA調(diào)度接收功能：Application/LEACH instproc recv args Application/LEACH instproc recvADV_CH msg Application/LEACH instproc recvJOIN_REQ nodeID Application/LEACH instproc recvADV_SCH order Application/LEACH instproc recvDATA msg 發(fā)送功能：Application/LEACH instproc sendData Application/LEACH instproc send mac_dst link_dst type msgdata_size dist code Application/LEACH instproc send_now mac_dst link_dst type msg data_size dist code Application/LEACH instproc SendDataToBS Application/LEACH instproc SendMyDataToBS 分析（五）由leach 分析三可知，一般節(jié)點(diǎn)的應(yīng)用為Application/LEACH。則現(xiàn)在就是如何選擇簇頭節(jié)點(diǎn)和設(shè)置門檻值。我們接下來分析leach 分析4中紅色的方法。在leach 分析3中創(chuàng)建一個(gè)Application/LEACH對象則就會自動調(diào)用start方法。Application/LEACH instproc start $self mac set node_num_ $self nodeID $self decideClusterHead $self checkAlive 在這個(gè)方法中會調(diào)用decideClusterHead和checkAlive方法。Application/LEACH instproc GoToSleep global opt ns_ $self instvar begin_idle_ begin_sleep_ $self node set netif_(0) set sleep_ 1 # If node has been awake, remove idle energy (e.g., the amount of energy # dissipated while the node is in the idle state). Otherwise, the node # has been asleep and must remove sleep energy (e.g., the amount of # energy dissipated while the node is in the sleep state). if $begin_idle_ > $begin_sleep_ set idle_energy expr $opt(Pidle) * expr $ns_ now - $begin_idle_ $self getER remove $idle_energy else set sleep_energy expr $opt(Psleep) * expr $ns_ now - $begin_sleep_ $self getER remove $sleep_energy set begin_sleep_ $ns_ now set begin_idle_ 0分析（六）在start中調(diào)用下面這個(gè)方法。Application/LEACH instproc decideClusterHead global ns_ chan opt node_ $self instvar alive_ TDMAschedule_ $self instvar begin_idle_ begin_sleep_ # Check the alive status of the node. If the node has run out of # energy, it no longer functions in the network. set ISalive $self node set netif_(0) set alive_ if $alive_ = 1 if $ISalive = 0 puts "Node $self nodeID is DEAD!" $chan removeif $self node set netif_(0) set alive_ 0 set opt(nn_) expr $opt(nn_) - 1 set ISalive $self node set netif_(0) set alive_ #從網(wǎng)絡(luò)接口netif中查看當(dāng)前節(jié)點(diǎn)狀 況如果節(jié)點(diǎn)存活，但是節(jié)點(diǎn)能量耗光，則$chan removeif $self node set netif_(0)將節(jié)點(diǎn)信道中移出，并將節(jié)點(diǎn)設(shè)置為死亡。節(jié)點(diǎn)的總數(shù)目減少一個(gè)。if $opt(eq_energy) = 1 # # Pi(t) = k / (N - k mod(r,N/k) # where k is the expected number of clusters per round # N is the total number of sensor nodes in the network # and r is the number of rounds that have already passed. # set nn $opt(nn_) if expr $nn - $opt(num_clusters) * $round_ < 1 set thresh 1 else set thresh expr double($opt(num_clusters) / expr $nn - $opt(num_clusters) * $round_ # Whenever round_ is 0, all nodes are eligible to be cluster-head. if $round_ = 0 $self hasnotbeenClusterHead # If node has been cluster-head in this group of rounds, it will not # act as a cluster-head for this round. if $self hasbeenClusterHead? set thresh 0 else # # Pi(t) = Ei(t) / Etotal(t) * k # where k is the expected number of clusters per round, # Ei(t) is the node's current energy, and Etotal(t) is the total # energy from all nodes in the network. # set Etotal 0 # Note! In a real network, would need a routing protocol to get this # information. Alternatively, each node could estimate Etotal(t) from # the energy of nodes in its cluster. for set id 0 $id < expr $opt(nn)-1 incr id set app $node_($id) set rca_app_ set E $app getER query set Etotal expr $Etotal + $E set E $self getER query set thresh expr double(expr $E * $opt(num_clusters) / $Etotal 上面是對thresh的計(jì)算，當(dāng)(N - k mod(r,N/k)<1，則將thresh設(shè)置為1，否則節(jié)點(diǎn)thresh=k / (N - k mod(r,N/k)，每個(gè)節(jié)點(diǎn)在一個(gè)1/p中都要成為簇頭節(jié)點(diǎn)一次。p=簇頭節(jié)點(diǎn)占所有節(jié)點(diǎn)的比例，在r=0的時(shí)候每個(gè)節(jié)點(diǎn)都有機(jī)會吃呢更為簇頭節(jié)點(diǎn)。如果節(jié)點(diǎn)成為過簇頭節(jié)點(diǎn)則thresh=0，則這個(gè)節(jié)點(diǎn)在1/p輪后才可以成為簇頭節(jié)點(diǎn)。 if $self getRandomNumber 0 1 < $thresh puts "$nodeID: *" puts "$nodeID: Is a cluster head at time $ns_ now" $self setClusterHead set random_access $self getRandomNumber 0 $opt(ra_adv) #opt(ra_adv) in leach.tcl $ns_ at expr $now_ + $random_access "$self advertiseClusterHead" else puts "$nodeID: *" $self unsetClusterHead 如果thresh>getRandomNumber，則節(jié)點(diǎn)成為簇頭節(jié)點(diǎn)。然后調(diào)用advertiseClusterHead方法。set next_change_time_ expr $now_ + $opt(ch_change) $ns_ at $next_change_time_ "$self decideClusterHead" $ns_ at expr $now_ + $opt(ra_adv_total) "$self findBestCluster"當(dāng)節(jié)點(diǎn)成為簇頭節(jié)點(diǎn)，則節(jié)點(diǎn)調(diào)用 advertiseClusterHead方法。 set chID $self nodeID set currentCH_ $chID pp "Cluster Head $currentCH_ broadcasting ADV at time $ns_ now" set mac_dst $MAC_BROADCAST set link_dst $LINK_BROADCAST set msg list $currentCH_ set datasize expr $BYTES_ID * llength $msg # Send beacons opt(max_dist) meters so all nodes can hear. $self send $mac_dst $link_dst $ADV_CH $msg $datasize $opt(max_dist) $code_將該節(jié)點(diǎn)設(shè)置為簇頭節(jié)點(diǎn)，設(shè)置當(dāng)前節(jié)點(diǎn)所處的簇號。然后發(fā)送數(shù)據(jù)，廣播該節(jié)點(diǎn)為簇頭信息到全局網(wǎng)絡(luò)。在$ns_ at expr $now_ + $opt(ra_adv_total) "$self findBestCluster"調(diào)用findBestCluster方法。分析（七）當(dāng)簇頭發(fā)出了一個(gè)ADV類型的包時(shí)，其他的節(jié)點(diǎn)會接收這個(gè)包，并會將發(fā)送這個(gè)包的簇頭的節(jié)點(diǎn)號按順序先后記錄在clusterChoices_中，還會計(jì)算每個(gè)簇頭到接收節(jié)點(diǎn)的距離并記錄在clusterDist_中。這樣可以方便每個(gè)節(jié)點(diǎn)選簇的時(shí)候進(jìn)行比較。具體的實(shí)現(xiàn)在ns-leach.tcl中的recvADV_CH函數(shù)中。findBestCluster if $self isClusterHead? # If node is CH, determine code and create a TDMA schedule. set dist_ $opt(max_dist) set currentCH_ $nodeID set myADVnum_ $self mac set myADVnum_ # There are opt(spreading) - 1 codes available b/c need 1 code # for communication with the base station. set numCodesAvail expr 2 * $opt(spreading) - 1 set ClusterCode expr int(fmod($myADVnum_, $numCodesAvail) + 1 $ns_ at expr $now_ + $opt(ra_adv_total) + $opt(ra_join) "$self createSchedule" 如果這個(gè)節(jié)點(diǎn)是簇頭節(jié)點(diǎn)，設(shè)置為當(dāng)前的簇頭， set numCodesAvail expr 2 * $opt(spreading) - 1 set ClusterCode expr int(fmod($myADVnum_, $numCodesAvail) + 1這兩句沒看懂在一個(gè)隨機(jī)時(shí)間后調(diào)用createSchedule，節(jié)點(diǎn)根據(jù)自己收到的clusterChoices，選擇最近的簇頭作為簇頭節(jié)點(diǎn)。選擇好簇頭節(jié)點(diǎn)就informClusterHead。發(fā)送完數(shù)據(jù)就進(jìn)入休眠狀態(tài)。Application/LEACH instproc createSchedule global ns_ opt ADV_SCH MAC_BROADCAST BYTES_ID $self instvar clusterNodes_ TDMAschedule_ $self instvar dist_ code_ now_ beginningE_ set numNodes llength $clusterNodes_ set chID $self nodeID if $numNodes = 0 set xmitOrder "" puts "Warning! There are no nodes in this cluster ($chID)!" $self SendMyDataToBS else # Set the TDMA schedule and send it to all nodes in the cluster. set xmitOrder $clusterNodes_ set msg list $xmitOrder set spreading_factor $opt(spreading) set datasize expr $spreading_factor * $BYTES_ID * llength $xmitOrder pp "$chID sending TDMA schedule: $xmitOrder at time $ns_ now" pp "Packet size is $datasize." set mac_dst $MAC_BROADCAST set link_dst $chID $self send $mac_dst $link_dst $ADV_SCH $msg $datasize $dist_ $code_ set TDMAschedule_ $xmitOrder set outf open $opt(dirname)/TDMAschedule.$now_.txt a puts $outf "$chIDt$TDMAschedule_" close $outf set outf open $opt(dirname)/startup.energy a puts $outf "$ns_ nowt$chIDtexpr $beginningE_ - $self getER query " close $outf在recvADV_SCH給每個(gè)節(jié)點(diǎn)一個(gè)時(shí)間間隙發(fā)送數(shù)據(jù) set frame_time_ expr expr 5 + llength join $order * $opt(ss_slot_time) set xmitTime_ expr $opt(ss_slot_time) * $ind set end_frm_time_ expr $frame_time_ - $xmitTime_ set xmitat expr $ns_ now + $xmitTime_ pp "$nodeID scheduled to transmit at $xmitat. It is now $ns_ now." if expr $xmitat + $end_frm_time_ < expr $next_change_time_ - 10 * $opt(ss_slot_time) $ns_ at $xmitat "$self sendData"具體實(shí)現(xiàn)方法看不太懂。