Posted at 11.18.2018
Network simulation is a method of investigation in network technology. Along the way of investigating a new technology, scheduled to various reasons, it is costly and unrealistic to actually test a network system. In such situation, simulation becomes one of the better available alternatives in testing, analysis and validation. Network simulation gets the features of small circuit and low priced, and it is easier for researchers to use other's research, in order to concentrate on this part and no need to spend a lot of time on other area of the system.
NS2 is a simulation program that is developed in free open up source for network solutions. Researchers can certainly put it to use for the introduction of network technology. Until today, NS2 contains rich modules that are almost related to all or any areas of network technology.
Wireless network marketing communications obtained a rapid development lately. Ad hoc systems do not need the support of cable connection infrastructure; the communication is attained by free mobile network hosts. The introduction of random network has advertised the accomplishment of the process of free communication at any environment, at the same time it has also provided an effective communication solution of military services, disaster pain relief and temporary communications.
Considering the random network is constantly moving, and the network topology is changing, which means traditional internet routing protocols (e. g. RIP, OSPF) are not have the ability to adapt in to the real need of ad hot sites. Therefore there are extensive specialised routing protocols are made for the ad hoc network, the purpose of this newspaper is to compare, analyse and measure the most popular routing protocols for ad hoc networks by running the simulation test with NS2.
"A mobile ad hoc network (MANET), sometimes called a mobile mesh network, is a self-configuring network of mobile devices connected by wireless links. "
Along with the desire of eliminate wired network constraints and be able to communicate anytime and any place, wireless network communications obtained a rapid development in recent years. Mobile communications may be accomplished by portable personal computers with wireless interface equipped and PDAs. Most up to date mobile communications need a wired infrastructure, e. g. basic station. To be able to communicate without fix infrastructure, a new network technology - RANDOM network technology comes up at the historical moment. Random networks don't need the support of cable connection infrastructure; the communication is attained by free mobile network hosts. The introduction of random network has promoted the achievement of the procedure of free communication at any environment, at the same time it has also provided a powerful communication solution of army, disaster relief and temporary marketing communications.
Each device in a MANET is absolve to move independently in virtually any direction, and can therefore change its links to other devices frequently. Each must onward traffic unrelated to its own use, and therefore be a router. The principal challenge in creating a MANET is equipping each device to continually keep up with the information necessary to properly route traffic.
Such sites may operate independently or may be linked to the bigger Internet.
Ad-hoc network was formerly found in the armed service field. With all the developments of cordless networks, it offers started the development in the civilian fields. A mobile ad-hoc network doesn't need any infrastructures, any node can easily and automatically form the network, and each node can move openly and can become a member of or leave the network anytime. The characteristics and advantages of fast deployment, invulnerability makes mobile ad-hoc becoming more and more widely used in either armed forces or civilian domains.
In recent years, as the rising cordless communication network, Ad-hoc is slowly but surely getting more attention of the industry and be a study hotspot. Ad-hoc networking helps flexible and convenient communication with no support of infrastructure, this technique broadens the fields of mobile marketing communications and has a shiny future.
Ad hoc network can be thought to be the mix of mobile communication and computer network. In random networks, computer network packet exchange device is used somewhat than circuit turning mechanism. Communication hosts are usually lightweight computer, personal digital assistants (PDA) and other mobile devices. RANDOM network is different from mobile IP network in the current Internet environment. In mobile IP systems, mobile hosts can web page link and access the network through resolved wired network, cordless hyperlink and dial up website link, and in ad hoc network, these is merely a wireless link connection. In mobile IP networks, the communication have to be supported by adjacent platform stations but still using the traditional internet routing protocol, however, random networks do not have the support of these facilities. Furthermore, a mobile variety in the mobile IP network is only a typical end device which doesn't have routing function. If the mobile host goes from one zone to another will not change the network topology, and in RANDOM networks the movement of mobile hosts would lead to topology change.
The thesis is to analyze on the Ad-hoc networking function and its own network coating through simulation with NS2, mainly focused on the assessment and evaluation of the favorite ad-hoc routing protocols. The aim of this article is to research and develop on the key technology of self-configuring network - routing protocols, based on ad-hoc network framework.
Ad Hoc wireless network has its particularity, in the formation of real use of the working network, the application form size, scalability and the reliability and real-time requirements must be taken full profile.
In addition, due to the unique structure of the ad hoc network, the characteristics of ad hoc network should be completely considered when design and build the network, which will help us to design a routing protocol that is suited to particular network structure in order to increase the performance over the network.
Ad Hoc wireless network topology can be split into two types: Flat framework and hierarchical structure, in chiseled network framework, all network nodes have identical status.
However, in the hierarchical composition of the RANDOM cordless network topology, the whole network is composed of clusters for the subnet, each cluster involves a cluster head and multiple cluster users, the cluster mind forms a higher level network. Each cluster mind and cluster members are powerful and automated networking. The hierarchy is dependant on different hardware configurations, and hierarchical composition can be divided into single-band and multi-band classification framework. Single strap hierarchy use one frequency in communication, all nodes use the same frequency. But in multi-band hierarchy, if there are two networks in various levels exist, the low level network has an inferior communication range and higher-level network has a larger communication range, cluster customers use the same rate of recurrence to communicate, cluster head nodes uses one regularity to talk to cluster members and another rate of recurrence to keep up the communication with cluster heads.
There are advantages and disadvantages can be found in either flat or hierarchical network buildings: the composition of flat structure network is easy, each node has an equal status, there are multiple pathways can be found in communication of the foundation node and vacation spot node, therefore no network bottlenecks, and the network is relatively safe. However, the biggest downside is the limited network size, when the network range growing, routing maintenance over head exponential development and take in the limited bandwidth; Hierarchical network composition is not tied to the range of network, the scalability is good, and because of clustering, routing over head is relatively smaller, although there is the need of sophisticated cluster head selection algorithm in hierarchical structure, but because of hierarchical network composition with high system throughput, node localisation is simple, therefore random network is currently increasingly demonstrating grading style, many network routing algorithms suggested are based on the hierarchical network structure model.
Wireless random network is a combination of mobile communications and computer sites, each node in the network have both router and host functions. The characteristics of ad hoc networks in mainly in the next areas:
Dynamically changing network topologies:
Ad Hoc systems have no fixed infrastructure and central management communications equipment, network nodes can arbitrarily proceed to any direction in virtually any speed rate, in conjunction with the energy change of wireless transmitter device, the environment impact and the sign mutual disturbance between each other, which all will result in vibrant changes of the network topology.
the working energy provided to the mobile hosts in RANDOM sites are limited, and the mobile coordinator with more energy loss, will reduce the Ad Hoc network functions; on the other hand, the network itself provides limited bandwidth and sign conflicts and Disturbance, which results the mobile host with limited available bandwidth which is normally much less than the theoretical maximum bandwidth.
if two network nodes are not in the same network coverage because of the limited resources available, multi-hop may be used in RANDOM network communication, to be able to attain the communication between the source variety and destination host which are not in the same network coverage.
Limited physical security:
the communication of Ad Hoc network nodes are through the cellular channel, the information transmitted is very vulnerable, and eavesdropping, retransmission, falsify or forgery harm may be accomplished easily, If routing standard protocol once experienced the malicious attacks, the complete self-organizing networks won't work properly.
These top features of the RANDOM network have made a particular question in the routing algorithm design. An acceptable routing algorithm must take the factors of limited network resources, powerful network topology changes and enhance the network throughput into consideration.
Ad-Hoc Wireless network routing protocols
The key concern in ad hoc network design is to develop a routing standard protocol that can provide high quality and high efficient communication between two nodes. The mobility characteristic in the network makes the network topology constantly changing, the traditional online routing protocol struggles to adjust to these characteristics therefore the routing standard protocol that is specialised for ad hoc networks is needed, According to earlier on the RANDOM network structures and features explained, the look of the routing standard protocol must meet up with the following conditions:
The need of quick response capabilities for dynamic network topology, and stay away from routing loops from developing, and provide simple and convenient network node localise method.
Must be proficiently use of the limited bandwidth resources, and make an effort to compress unnecessary over head.
Limit the number of intermediate transfer through the implementation of multi-hop, generally only 3 times.
Must minimise the launch time and amount of introduction data, to conserve limited working energy.
In possible conditions, make the look of routing standard protocol with securities to lessen the possibility of being attacked.
According to the specific characteristics of ad hoc cordless network routing protocols, lately, there are a variety of random network routing protocols have been suggested. IETF's MANET working group happens to be focused on research Ad Hoc network routing protocols, and protocols many standard protocol drafts, such as DSR, AODV, ZRP etc. in addition, the professional experts also shared a extensively amount of articles related to Ad hoc network routing protocols and proposed many network routing protocols for the random sites, such as DSDV, WRP etc. Based on the routing trigger basic principle, the current routing protocols can be divided into three types: Proactive Routing protocol, Reactive routing protocol and Cross types routing protocols.
Proactive routing standard protocol is also called Table-driven routing standard protocol, each node maintains a routing desk which has the routing information to attain the other node, and changes the routing table constantly matching the network topology changes, and then the routing desk can accurately reveal the topology framework of the network. After the source code must send information, the route to the destination node can be immediately obtained. This type of routing standard protocol is usually modified from the existing wired network routing protocol to adapt to the wireless random network requirements, like the Destination-Sequenced Distance Vector standard protocol, which is altered from the Routing Information Standard protocol (RIP). Therefore, this type of routing process has a small delay, but requires a great deal of control concept, the over head is large. Frequently used proactive routing protocols include DSDV, HSR, GSR, WRP etc.
Destination-Sequenced Distance Vector (DSDV)
DSDV avoids the generation of routing loops by set serial number for each road, using time-driven and event-driven technology to control the transfer of routing table, i. e. a routing table is placed in each moving node locally, it includes valid factors, routing hops and vacation spot routing serial amount etc. destination routing serial quantity is used to tell apart old and new path to avoid routing loops.
Each node regularly sends the local routing table to the neighbour nodes, or when the routing stand changes, the information will also be exceeded to neighbouring nodes, when there is absolutely no moving nodes, use a larger packet with longer interval to upgrade the route. If the neighbouring node will get the information has modified routing stand, it will first compare the serial variety of destination node, the routing with greater serial quantity will be used and the one with smaller serial amount will be eradicated, of course, if the serial number will be the same, the best optimised course (e. g. shortest course) will be utilized.
Each node must occasionally exchange the routing information with adjacent nodes, the routing information update is can also be brought about by the changes in routing stand. There are two ways to update the routing stand, Full dump, i. e. the topology revise message includes the complete routing desk, which is mainly applied to the truth of fast changing network. One other way is Incremental revise, where update message contains only the altered part in routing, such way is usually found in a network with slower changes.
HSR is a routing process that can be used in hierarchical network, nodes at a higher level helps you to save all the positioning information of its peers, rational collection address is given along from the root node at the highest level to the leaf node at the cheapest level, node address can be utilized by series address.
GSR protocol works similar with the DSDV device, it uses link-state routing algorithm, but avoids the flooding of routing packets, which include an adjacent node table, network topology stand, next hop routing table and the length table.
WRP is a distance-vector routing standard protocol, each node keeps a distance stand, routing table, link overhead stand and packet retransmission table, through the Brief Path Spanning Tree (SST) of the neighbouring node to generate its SST, and then transfer updates. When there is absolutely no any change in the network routing, the recipient node must return an idle meaning to show the connection, otherwise modify the length table to look for better course. The feature of the algorithm is that whenever any changes of the neighbouring node is recognized, and then checks the sturdiness of all adjacent nodes to be able to get rid of the loop, has a faster convergence.
Reactive Routing protocol is also called on-demand routing protocol, it detects the route only when needed. Nodes do not need to maintain routing information constantly, it will initiate route research only when the packet is have to be sent. Compare with proactive routing protocols, the over head of reactive routing process is smaller, but the packet transmission delay is larger, this means it isn't suitable for real time applications. Popular reactive routing protocols include AODV, DSR, TORA and so forth.
2. 2. 2 Dynamic Source Routing (DSR)
"DSR was created to restrict the bandwidth used by control packets in random wireless networks through the elimination of the periodic table-update emails required in table-driven procedure. "
DSR comprises two main mechanisms - Option Discovery and Path Maintenance. The Route Discovery mechanism can be used when the source node needs to send a packet to the destination node but does not know the path.
When the foundation node is using a source path to reach the destination node, source node uses the path maintenance mechanism to identify the path that cannot be used due to the topology changes.
In DSR, way discovery and course maintenance mechanisms are completely on-demand procedure, DSR will not require any periodic routing broadcast packets and link state detection packets.
TORA can be an adaptive distributed routing algorithm predicated on hyperlink reversal method, which is principally used for high-speed powerful multi-hop cordless network. Being a source initiated on-demand routing standard protocol, it is able to find multi-paths from the foundation to the vacation spot node. The primary characteristics of TORA are, when topology changes, the control note transmission in geographic area of topology changes only. Therefore, the node only needs to maintain the information of adjacent nodes. The process consists of three parts: option generation, road maintenance and road deletion. Inside the initialisation level, the transmission collection range of the destination node is set to 0. The QRY packet which contains the vacation spot node ID broadcast by the foundation end and a node with a transmitting sequence number that is not 0 reactions to the UDP packet. The node that receives UDP packet gets the sequence number higher than the foundation node by 1, and the node with higher sequence number is defined as the upstream node. Through this technique, a Directed Acyclic Graph (DAG) from the source to the destination node can be created. When nodes move, routes have to be rebuilt. Within the route deletion stage, TORA gets rid of the invalid option by broadcasting a CLR. You can find one problem that exists with TORA, which is when multiple nodes proceeds to road selection and deletion, routing oscillation will be produced.
AODV is an improvement to the DSDV algorithm, however the difference with DSDV is that it is a Reactive routing process. In order to find the route leading to the vacation spot node, the source end will broadcast a routing question packet, and adjacent subsequently broadcast the packet to the surrounding nodes before packet was delivered to the vacation spot node, or, to the intermediate node which includes the routing information to the destination node. A node will discard duplicated question packet received, the serial amount of routing get packet is to avoid routing loops, and is able to determine whether the intermediate node has responses to the matching routing requests. Whenever a node forwards a option request packet, it will mark the Identification of its upstream node in to the routing table, in order to create a reverse path from the destination node to the foundation node. When the foundation end moves, it will re-initiate route breakthrough algorithm; if the intermediate nodes move, then the adjacent node will see the link failure and send the hyperlink failure note to its upstream node and distributed the message completely to the foundation node, afterwards the source node re-launches the path discovery process based on the circumstances.
The achievements of AODV is a blend of DSR and DSDV protocols. It has the features of course discovery and way maintenance in DSR, and at exactly the same time use by-hop routing, collection quantity and Beacon communications that implemented in DSDV.
In wireless ad hoc networks, neither proactive nor reactive routing protocols exclusively can solve the routing problem completely, therefore cross routing protocols which combines the advantage of both proactive and reactive protocols have been suggested by the researchers, including the Zone Routing Standard protocol (ZRP). ZRP is a blend of proactive and reactive routing protocols, all nodes within the network to themselves as the centre of an virtual zone, the amount of nodes in the region is related to the radius set of the area, and the areas overlap, this is the difference with clustering routing. It uses proactive routing algorithm within the zone, the centre node uses Intrazone Routing protocol to keep in the area.
The program that will be used in simulation is Windows XP Professional + Cygwin + NS2.
NS2 is a simulation system that is developed in free available source for network technologies. Researchers can easily make use of it for the introduction of network technology. Until today, NS2 is made up of rich modules that are almost related to all or any areas of network technology. Since the release 2. 26, NS2 has quit support with House windows systems, therefore to receive the latest NS2 running on the Windows XP, Cygwin is needed. Cygwin is an UNIX emulator on Glass windows platform.
Normally, NS2 simulation can be divided into the following steps:
1. Compose necessary components: i. e. add or remove new components
2. Evaluating: test if the component composed is validated. When the aspect in the collection satisfies the simulation needs (e. g. simulation process based on existing protocols in the collection), then your simulation starts off from the 3rd step.
3. Create Otcl script file: configure the topology framework of the simulating network, and identify the basic hyperlink features, protocols that contain been employed by moving nodes, and volume of nodes etc, and binding the terminal device protocol, setting up the landscape and traffic load of simulation (TCP stream or CBR stream), setting simulation start and end time etc, and set trace items of the script file, trace document is the record that records all of the occurrences of simulation process, and also can establish the nam object at the same time, nam is the tool to show the network jogging animation.
4. Use NS order to implement script document: once carried out, *. tr file will be produced in the same listing of the script data file, to track record the simulation results. if nam subject is defined in the script document, *. nam document will be generated in the same index.
5. Analyse track file: because of the large size of trace file, we will need to create gawk program to process the info after simulation (assess packet delivery particular date, routing overload, and throughput etc), then use the pulling tools to create the graph for direct analysis.
In NS2 the typical routing protocols such as DSDV, DSR, TAORA and AODV are already integrated; the source code of routing protocols is positioned in C:\cygwin\home\Administrator\ns-allinone-2. 34\ns-2. 34, show in figure 1. 1
Take AODV as an example (fig. 1. 2), within the ADOV folder, aodv. cc and aodv. h are the most crucial files, they defines the main efficient features. Under standard circumstances, we do not need to modify the source code of the protocols.
Fig. 1. 2 AODV Routing Protocol
According to the simulation model designed, each routing protocol (DSDV, DSR, AODV, and TORA) will be compared in small (20 nodes) and medium (50 nodes) random cellular network. The matching scripts made up are: dsdv. tcl, dsr. tcl, aodv. tcl and tora. tcl (see appendix).
Taking aodv. tcl for example, the coding is show in fig. 3. 2. 1
Partial scripts in aodv. tcl
Some script reason of most important codes in aodv. tcl
#Quantity of nodes in simulation scenario
#Routing protocol to be simulated
#Simulation time length
#Duration of scene
#Width of scene
set val(tr) out50. tr
#Output track file
set val(nam) out50. nam
#Productivity nam file
set opt(cp) "cbr50"
set opt(sc) "scen50"
In addition, write the following assertion in script head to make a simulation ns_ subject:
Tracking the file object is used to designate the Trace data file (with. tr extension) in tracking of the simulation data. NS2 helps record application layer, routing layer, Apple pc coating and node movements those four types of data in difference layers. The data that should be registered can be specified in settings in the simulation process. The info in of each layer that trace object specified are noted in the trace file, product labels are added to distinguish them. Furthermore, NS2 also supports NAM tool simulation process visualisation, such function needs to create the NAM track file thing to specify the trace file of data of simulation data. The next statements are used to generate those two trace file object detailed.
#Generate trace record:
set tracefd[open out50. tr w];
#Generate NAM trace file object:
set namtracefd[open up away50. nam w]
Data stream era tool cbrgen is utilized to generate traffic tons, which can make the TCP heavy steam and CBR steam. Cbrgen. tcl document (see appendix) can be utilized as following:
Codes are defined as following:
#TCP stream or CBR stream
#Number of nodes
#Specify amount of random seeds
#Maximum connection of each node
#Overload of every stream connection
The format is employed as following:
ns cbrgen. tcl [-type cbr|tcp] [-nn nodes] [-seed seed] [-mc links] [-rate rate]
. /setdest is utilized to randomly generate the nodes movements scene needed form wireless network, used as pursuing (2 variations):
Which "speed" type placed to consistent/normal"pause type" establish to constant/even.
The NAM function is employed to run the animation of specific track output format, the end result data file can be based on real or simulated environment. For instance, the trace record that is from the productivity of NS simulator.
The commands to control to regulate NAM computer animation in NS2 as following: nam out. nam
$node color [color]
Setting the color of node
$node shape [form]
Setting condition of node
$node label [label]
Setting name of node
$node label-color [lcolor]
Setting display shade of node name
$node label-at [ldirection]
Setting display location of node name
$node add-mark [name] [color] [form]
$node delete-mark [name]
2. Website link and Queue
Use the next commands to make the agent you wish to display looks as AgentName in the pack.
The variables of movement picture and node stream are in the furniture shown below:
Number of nodes
500 x 500 m
Maximum moving speed
Node communication distance
Type of service
5, 10, 15, 10, 25, 30-50
Trace document analysis
Performance parameter research model
The sign to gauge the performance of ad hoc network routing protocol is commonly including qualitative sign and quantitative sign. Qualitative indicator details the entire performance of a specific facet of the network, like the security, distribution procedure, provide loop free way and whether to aid single channel etc. and quantitative indicators can explain the performance of a certain aspect of the network in additional information. The quantitative indication of packet delivery ratio, average end to end wait and throughput etc can be used to gauge the performance of network routing protocols.
a. Packet delivery proportion: is a ratio of the number of packet sent from the source node and the number of packet that have been received by destination node in the application form level, which not only identifies the loss rate observed in the application part, but also indicate the maximum throughput backed by the network. It is the signal of routing protocol completeness and correctness.
it can be calculated with the following equation, which N symbolize the packets successfully delivered, rt symbolizes the time that packet come to the destination node, and st stand for packet sending time.
Routing overhead is the total amount of control packets of most routes, in a multi-hop routing each hop transmitting is the same as one packet transmitting. Routing overhead can be used to compare the scalability, the ability to adapt to networking congestion and the efficiency of different routing protocols. It could be calculated with the following formula:
Routing overhead = The Total amount of routing control packets
The output record out. tr produced in simulation research will be filtered by selecting all the packets in Agent layer, calculate all the number of data packets delivered by this covering and the amount of data packets that has been successfully received, and then split the number of packets received by the amount of packet sent, in order to have the packet delivery rate. Use awk command could get the data of packet delivery rate, end to get rid of average hold off, routing overhead, the gawk script is shown below:
BEGIN sendpacket = 0;
recvpacket = 0;
$0 ~/^s. * AGT/ sendpacket ++ ; #Calculate the quantity of packets sent
$0 ~/^r. * AGT/ recvpacket ++ ; #Determine the number of packets received
END printf "cbr send:%d recv:%d, getRatio:%. 4f \n", sendpacket,
awk -f avdelay. awk out. tr > avdelay
awk -f getratio. awk out. tr > getratio
awk -f routeload. awk out. tr > routeload
In obtaining the desired data, we may use the sketching tool Gnuplot to plot the quantitative data curve.
Through loading data files to start out graph story, run insert "gnuplot. plt.
gnuplot>insert "gnuplot. plt
Obtain the packet delivery rate and analysis chart of 50 nodes. We ought to alter the coordinates, size size and data file name in plotting, and focus on the key tips.
Gnuplot. plt code is shown below:
unset xtics # keep all other things simple
set origins 0, 0
set subject "Paeket Delivery Fraetion"
set xlabel "velocity(m/s)"
set ylabel "Paeket Delivery Fraetion(%)"
set xtics 5. 0
set ytics 1000. 0
set yrange[0:7000] #the two axes scale range are equal
set key top left
set key box
set size 0. 5, 0. 5
set origins 0, 0. 5
plot "50MR. txt" using 1:2 subject "aodv" w lp lt 3 lw 2 pt 3 ps 2
#The first chart occupies the very best left one fourth of the display.
set size 0. 5, 0. 5
set origin 0, 0
plot "50MR. txt" using 1:3 title "dsdv" w lp lt 4 lw 2 pt 4 ps 2
# The next chart occupies the bottom left quarter of the screen
set size 0. 5, 0. 5
set origin 0. 5, 0. 5
plot "50MR. txt" using 1:4 title "dsr " w lp lt 5 lw 2 pt 5 ps 2
# The third chart occupies the top right 1 / 4 of the screen
set size 0. 5, 0. 5
set origins 0. 5, 0
plot "50MR. txt" using 1:5 subject "tora" w lp lt 6 lw 2 pt 6 ps 2
# The forth chart occupies underneath right 1 / 4 of the screen
Simulation results assessment and analysis
Delivery rate comparability of each protocol
Fig. 1. 1. 1 and fig 1. 1. 2 are displaying the evaluation of packet delivery rate for each protocol in case there is rate changing in a little (20 nodes) and medium (50 nodes) scaled ad hoc network separately. The entire simulation is maintained for 300 seconds. The horizontal axis is the node ability to move speed (m/s), and the vertical axis is the worthiness of packet delivery rate.
Fig. 1. 1. 1: Packet Delivery Rate of every routing protocol in a little ad hoc network (20 nodes)
In most instances, due to the regular move of nodes, the routing stand in the proactive routing process mechanism DSDV, will most likely become invalid therefore struggling to identify the available routes which leads packet damage.
As the rate rises, the network topology changes more and more violent, there has to be a great upsurge in number of option revise packets in the cellular programs of the network, especially in routing protocol DSDV, as the table content is need to be updated each time the topology changes.
The system of reactive routing protocols (AODV, DSR, and TORA) is way better in inhibiting the possible circumstances of routing table entries failing. The route proven only when a packet is required to be sent. Therefore the level of sensitivity of reactive routing protocols to the network topology changes is a lot less than proactive routing protocols.
Thus, in cordless ad hoc network, the packet delivery rate in proactive routing protocol (DSDV) is lower than reactive routing protocols (AODV, DSR and TORA). This effect is agrees well with the prior routing protocol evaluation.
In addition, we also within each protocol that in the small ad hoc network (20 nodes), the packet delivery rate gets higher when the nodes are moving at a higher speed; however in the medium random network (50 nodes), the packet delivery rate is lower when the node activity quickness gets higher.
The reason behind this results may be: the greater network weight leads more node energy utilization; the energy operates out prior to the packets appeared, which resulted in a lot of packet reduction, therefore result a significant reduction in effectively received quantity of packets.
Graphs fig. 1. 2. 1 and fig 1. 2. 2 are showing the evaluation of average end-to-end wait of each standard protocol in case there is velocity changing, for small (20 nodes) and medium (50 nodes) cellular ad hoc networks separately. The complete process of each protocol endures for 300 seconds.
The horizontal axis presents the moving velocity of nodes (in m/s), and vertical axis is the average end-to-end delay (in ms).
Fig. 1. 2. 1
Fig. 1. 2. 2 Average end to get rid of delay of each routing standard protocol in a medium ad hoc network (50 nodes)
Analysis of end-to-end average hold off graph for every routing protocol
We have found that in the tiny ad hoc network (20 nodes), proactive routing standard protocol (DSDV) gets the smallest end-to-end average hold off, and the reactive routing process (AODV, DSR and TORA) has a greater delay. The reason why of this is that when the proactive routing process (DSDV) must send a packet, it gets the route immediately from searching the routing desk, therefore gets a smaller wait; in addition, this maybe related to the network topology and network picture as well.
DSR, AODV and TORA are reactive routing protocols, which look up the routes only when a packet is needed to be directed, therefore with a more substantial delay.
At the same time, we can see from the graph of medium random network (50 nodes), at a higher speed, proactive routing protocol (DSDV) end-to-end average hold off increases and gets even higher than reactive routing protocol (TORA). Therefore the wait of proactive routing protocol (DSDV) increases combined with the increase of network overload and velocity of node activity.
In addition, the motion speed increase led frequent topology changes, which make the end-to-end average delay of every routing standard protocol relatively increase.
In addition, the motion acceleration increase led recurrent topology changes, which make the end-to-end average hold off of each routing standard protocol relatively increase.
Graphs fig. 1. 3. 1 and fig 1. 3. 2 are showing the contrast of routing overhead of each protocol in case there is speed changing, for small (20 nodes) and medium (50 nodes) cordless ad hoc systems separately. The entire process of each protocol lasts for 300 mere seconds. Within the graph generated, the horizontal axis symbolizes the acceleration of node motion (in m/s), and vertical axis symbolizes the routing over head (unit: range of routing packet)
Fig. 1. 3. 1: routing over head comparison of each protocol in small random network (20 nodes).
Fig. 1. 3. 2: routing overhead comparison of each process in medium random network (50 nodes).
DSDV is a proactive routing protocol, in the medium sized ad hoc network (50 nodes), nodes regularly exchange routing information, and quite simply its overhead is very little influenced by the node activity. Beneath the same movement rate, reactive routing protocols (DSR, AODV and TORA) has an increased routing over head than DSDV, TORA has the biggest overhead among them. With the velocity increase, the overhead of on-demand routing protocols are getting higher and higher, however in contrast, the over head of proactive routing standard protocol DSDV is on the decrease, the main cause of is that the process of routing get in reactive protocols corresponds to one route needed, and gets only 1 route every time, but the routing information changes in proactive protocols broadcasts all the paths, therefore multiple routes are available in one update; therefore reactive routing protocol has a more substantial overhead, and at the same time the increase of node motion speed also escalates the volume of route finding process in reactive routing standard protocol, which leads the rise of routing overhead.
But in DSDV standard protocol, the movement quickness increase shows its edge, the routing over head declines. This is because that TORA, DSR and AODV are all on-demand routing protocols, their costs will decrease with the loss of node movements, but raises with the increase of network fill.
The overhead of routing protocol TORA includes two parts, one part is continuous overhead that is not related to the moving quickness of nodes, and the other part is varying overhead that is associated with the motion of nodes. The first part is principally based on the Directed Acrylic Graph of composition, once Directed acrylic graph set up, there may be a multiple course available from the source node to the vacation spot node. Therefore the overhead is principally on the directed acrylic graph maintenance, this system requires the node send at least one Hello packet in each sign cycle.
And the next part is the routing packets for TORA to generate and maintain the routes, and the retransmission and verification packets of MEP to guarantee the reliable sequence transmitting.
Therefore TORA has a comparatively larger over head, the routing over head increases significantly in the beginning level with the node rate increase.
DSR uses caching technology and blended reception mode to hear the routing question packets, and so greatly reduces the routing overhead.
AODV gets the similar characteristics with DSR, the performance is also similar, and both routing over head is relatively low.
In the statement, we have been monitoring on the Ad hoc Network research, and utilize this as theoretical guidance for a organized study. With the task requirements of this thesis, we have conducted a quantitative examination for the four typical random routing protocols which may have been suggested (DSDV, AODV, DSR, TORA).
Familiar with the essential NS2 simulation process and draw out the simulation with those for kinds of routing protocols.
Planning simulation steps and simulates in NS2 simulation software based on theoretical analysis, likened the performance of four existing ad hoc routing protocols. And made an evaluation of quantitative evaluation, and finally provide a conclusion.
In the test, the numbers of nodes were place to 20 and 50 to signify the small and medium random network, and in the circumstances of quickness changes in 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 (m/s), quantitatively analysed and compared the packet delivery rate, end-to-end average delay and routing overhead of each routing process through the simulation experiment. From the evaluation of results, we can clearly see that because of the different process mechanisms, each standard protocol has the corresponding advantages and disadvantages in several performance indicators.
In general, reactive routing protocols (DSR, AODV, TORA) especially DSR and AODV have relatively higher packet delivery rate, as the packet delivery rate of DSDV is influenced by the network insert. In conditions of end-to-end wait, DSDV gets the lowest average wait; and in terms of over head, DSDV remains constant as it isn't much afflicted by the network load.
Routing over head of TORA raises with the increase of node amount and node movements speed.
Due to the diversity of application surroundings of random wireless networks, producing the quest for different requirements of performance. For instance, the system's survivability, concealment and confidentiality is more concerned in the military fields; but in wireless mobile meeting systems, the finish to end delay and packet delivery success rate is more pressured.
From the research and simulation results of above four types of routing protocols, we can easily see that different routing protocols has its own advantages and disadvantages, and thus adjust to different network environment.
However, the hope to have one routing algorithm to solve all the ad hoc network routing problems, and be the standard arrangement of ad hoc routing process seems unrealistic at the current stage. The perfect routing algorithm should be picked based on the precise request environment. The Crossbreed routing algorithm combines the benefits of both proactive and reactive routing protocols and its inherent overall flexibility, thus has a good request prospects.
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Section 4 - Simulation
Through NS2 simulation results, quantitatively analyse and compare the performance of various routing protocols.
Process of random simulation with NS2
Routing protocol comparison and performance analysis
Simulation settings and variables scripting
Process of simulation results files
Simulation model variables and performance indicators
Calculation of Performance indicators
Simulation process in details
Generate traffic loads
TCL scripting animation simulation
Trace record analysis
Gnuplot graph analysis
Comparison of packet delivery rate of every protocol
Average end to get rid of delay comparison of each protocol
Comparison of over head by rate increase
Section Six - Future research directions and work prospects
Section Seven - References
http://www. cww. net. cn/tech/html/2007/8/3/20078385592120_1. htm [Seen in 17/05/2010]
http://en. wikipedia. org/wiki/Mobile_advertising_hoc_network [Seen in 22/05/2010]
http://en. wikipedia. org/wiki/Destination-Sequenced_Distance_Vector_routing [Accessed in 20/05/2010]
http://en. wikipedia. org/wiki/Dynamic_Source_Routing [Utilized in 22/05/2010]
http://en. wikipedia. org/wiki/Advertisement_hoc_On-Demand_Distance_Vector_Routing [Accessed in 20/05/2010]
http://wiki. uni. lu/secan-lab/Temporally-Ordered+Routing+Algorithm. html [Reached in 20/05/2010]
Samuel Pierre, Michel Barbeau, Evangelos Kranakis  Ad-hoc, mobile, and cordless sites: Second International Conference
George Aggelou  Mobile ad hoc sites: from cellular LANs to 4Gsites
http://en. wikipedia. org/wiki/Ns_%28simulator%29